CN105704366B - Mixed format medium transmission system and method - Google Patents
Mixed format medium transmission system and method Download PDFInfo
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- CN105704366B CN105704366B CN201511015730.XA CN201511015730A CN105704366B CN 105704366 B CN105704366 B CN 105704366B CN 201511015730 A CN201511015730 A CN 201511015730A CN 105704366 B CN105704366 B CN 105704366B
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- H04L27/00—Modulated-carrier systems
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
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- H04L27/2601—Multicarrier modulation systems
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- H—ELECTRICITY
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
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- H04L27/38—Demodulator circuits; Receiver circuits
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- H04N23/661—Transmitting camera control signals through networks, e.g. control via the Internet
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Abstract
描述了用于操作摄像机的系统和方法。从图像传感器接收的图像信号可作为表征图像信号的多个视频信号进行处理。编码器可将基带和数字视频信号组合到输出信号中以在电缆上传输。视频信号可包括基本等时的基带和数字视频信号。解码器对上游信号解调以获得控制信号，该控制信号用于控制摄像机的位置和朝向以及基带和数字视频信号的内容。描述的系统和方法接收多种信号，提供与信号关联的同步信息，校正信号中的相移偏移，并采用或检测在信令过程中使用的编码方案。描述了用于检测信号存在的系统和方法。
Systems and methods for operating a camera are described. The image signal received from the image sensor may be processed as a plurality of video signals representing the image signal. Encoders combine baseband and digital video signals into an output signal for transmission over a cable. Video signals may include substantially isochronous baseband and digital video signals. The decoder demodulates the upstream signal to obtain control signals that are used to control the position and orientation of the camera and the content of the baseband and digital video signals. The described systems and methods receive a variety of signals, provide synchronization information associated with the signals, correct for phase shift offsets in the signals, and employ or detect the coding scheme used in the signaling process. Systems and methods for detecting the presence of a signal are described.
Description
The application is PCT international application no PCT/US2010/022772, international filing date on 2 1st, 2010, Chinese state
Family application number 201080015700.8, entitled " mixed format medium transmission system and method " application divisional application.
Technical field
The present invention relates generally to multi-media transmission system and relate more specifically to transmit high-definition digital view on single cable
The system and method for frequency and SD analog video.
Background technique
With the appearance of digital broadcast television and stream video technology, many has the number of enhancing clarity and advanced
Video camera, monitor and video recorder have become available.Closed-circuit television (CCTV) system nowadays provide HD video output and
Occasion of the digital video signal of compression for such as building management, the access control of facility and remotely to monitor.However, old
System stop in situ and SD analog video signal be in be widely used and in the mistake for being transitioned into digital high definition system
Still will continue in journey using.Specifically, coaxial cable (" coaxial ") has been deployed carrying from CCTV video camera to monitoring
The signal stood.The CCTV video camera of some deployment in local area network or the compressed vision signal of wide area transfers on network, and these
Internet protocol (IP) can be used as means of communication to transmit compressed vision signal in video camera.
Fig. 1 shows the legacy system using coaxial cable carrier SD analog video.Basic analog video camera 10 generally produces
The raw usable transmission of coaxial cable 11 is up to 300 meters of composite video baseband signal (CVBS).CVBS signal is commonly provided to
A kind of video recording system, the video recording system often include the digital video recordings device for recording CVBS in a digital format
(DVR)12.Conventional monitors 14 may connect to DVR 12 with and meanwhile show that the SD analog video, the SD analog video are general
Resolution ratio with 720*480 pixel.
Digital camera 16 may replace analog video camera 10 in some applications.Digital camera 16 can support serial digital
Interface (SDI), the serial digital interface can with the rate of about 270Mbps on coaxial cable 17 by uncompressed SD number
Word transmission of video is to DVR.
Fig. 2 shows the conventional methods that HD video (1920 × 1080 pixel) is transmitted in current deployment system.Firstly, number
Word video camera 20 can support high definition serial digital interface (HD-SDI) that HD-SDI can be with the rate of 1.5Gbps in coaxial cable 21
On uncompressed high-definition digital video is transmitted to DVR 22.The cable distance supported under such high transmission rates is reachable
100 meters.Secondly, standard class 5 (CAT 5) twisted-pair cables 25 can be used to exist for IP-based high definition (HD) video camera 24
Compressed digital HD video signal is generated on 100Mbps Ethernet, transmission range is 100 meters.Signal DVR 22
It receives and is recorded to make non real-time playback.Existing coaxial cable 26 can be used for bridging modulatedemodulate using class 5- coaxial cable
Adjust device 27,29 or other conversion equipments that video is transmitted to DVR 22 from video camera 24.So that camera transmissions digital video
The use of networking network allows these systems to add some upstream communications, usually control and audio signal 28.
Summary of the invention
The system and method that certain embodiments of the present invention provides video camera and operates video camera.Processor can be from image
Sensor receives picture signal and generates multiple vision signals of characterization picture signal.Encoder be used for baseband video signal and
Digital video signal group is combined into the output signal transmitted on cable.Baseband video signal whens vision signal may include basic waits
And digital video signal.Video camera can be used as closed circuit high definition television video camera.
It is according to the present invention in some terms, baseband video signal may include SD analog video signal and digital video signal
It can be modulated before being combined with baseband video signal.Digital video signal may include compressed high-definition digital video signal.Number
The frame rate of word vision signal can be lower than the frame rate of picture signal, and modulated digital signal is especially being supplied to video
In the case of transcripter.
In certain embodiments, configuration decoder is to from transmission cable or from the received stream signal of cordless communication network
It is demodulated, which is used to carry downstream visual.Demodulated stream signal may include control signal, the control letter
Number include control video camera position and direction signal, control by processor generate baseband video signal and digital video letter
Number signal and the signal that selects a part of picture signal to be encoded as baseband video signal.Controlling signal can also
Including the signal for selecting a part of picture signal to be encoded as digital video signal and for driving taking the photograph for such as loudspeaker
The audio signal of camera audio output.
The method of certain embodiments of the present invention offer transmitting video image.These methods can include: be imaged to from high definition
The received vision signal of equipment carries out frequency division multiplexing to obtain modulated digital signal；By by modulated digital signal with
Characterization vision signal base-band analog signal combination come generate output signal and simultaneously by output signal be sent to monitor and
Digital video storage device.These embodiments it is some in, monitor show vision signal baseband analog characterization and/or number
Word video memory records a series of high definition frames extracted from modulated digital signal using digital video recordings device.Number view
Frequency signal can be compressed.
In certain embodiments, transmission output signal includes that output signal is supplied to coaxial cable and/or is supplied to nothing
Line transmitter.It can demodulate from coaxial cable or the received input signal of wireless network to obtain control signal.Base-band analog signal
It can be generated and encoding a part of vision signal in composite video signal, and quasi- coding is in composite video signal
Control signal can be used to control for part vision signal.Controlling signal can control the position of video camera.Demodulating input signal can
Extraly an audio signal is generated from input signal.
Certain embodiments of the present invention provides the system and method for operating video camera.Processor can be from imaging sensor
It receives picture signal and generates multiple vision signals, control logic can be configured to make sound to by the received control signal of video camera
It answers and modulator can be configured to modulate digital video signal to obtain modulated signal.Multiple vision signals may include base band
Vision signal and digital video signal.Each of multiple vision signals represent at least part of camera field, and
Controlling signal can control the content of base band and digital video signal.Modulated signal and baseband video signal are usually by video camera
Simultaneous transmission.
Whens base band and digital video signal can be basic equal.Encoder can be by baseband video signal and modulated signal
Group is combined into the output signal for transmitting on cable.For example, control signal wirelessly can be received from wireless network.Through adjusting
Signal processed at least partly can be transmitted wirelessly.Digital video signal can be high-definition digital video signal, and can be
Compressed digital video signal.Control a part of the mobile ken by a characterization in vision signal of signal.
Detailed description of the invention
Fig. 1 explanation uses the prior art systems of coaxial cable carrier SD analog video.
The art methods of Fig. 2 explanation transmission high-definition digital video.
Fig. 3 describes the system for being used for transmission analog and digital video of some aspects according to the present invention.
Fig. 4 describes the networked systems for being used for transmission analog and digital video of some aspects according to the present invention.
The bandwidth for transmitting analog and digital video on coax that Fig. 5 shows some aspects according to the present invention is divided
Match.
Fig. 6 explains the example of the CCTV camera equipment of some aspects construction according to the present invention.
Fig. 7 explains the example of the modem used in DVR equipment of some aspects construction according to the present invention.
Fig. 8 explanation modem used in network exchange equipment that some aspects construct according to the present invention shows
Example.
Fig. 9 is the example of the frame structure used in ATSC DTV.
Figure 10 is the example of traditional frame synchronization grouping.
Figure 11 is the example of the data sectional in conventional data frame.
Figure 12 provides the simplified diagram of frame configuration.
Figure 13 is the block diagram of the modulator of some aspects according to the present invention.
Figure 14 is that the block diagram of the frame structure used in some embodiments of the invention indicates.
Figure 15 illustrates the operation of convolutional byte interleaver in some embodiments of the invention.
Figure 16 is the block diagram of the selectable code rate puncture trellis coded modulation used in certain embodiments of the invention.
Figure 17 explains the example of QAM mapping.
Figure 18 shows frame synchronization/mould grouping.
Figure 19 is the simplification frame structure used in some embodiments of the invention.
Figure 20 is the block diagram of the demodulator of some aspects according to the present invention.
Figure 21 is the block diagram of the camera side modem of some aspects according to the present invention.
Figure 22 is the block diagram of the monitor side modem of some aspects according to the present invention.
Figure 23 explains camera side base band-passband QAM modulation device of some aspects according to the present invention.
Figure 24 A and 24B explain monitor side passband-base band qam demodulator of some aspects according to the present invention.
Figure 25 explains the monitor side digital equalizer and carrier phase/frequency loop of some aspects according to the present invention.
Figure 26 shows the decaying described by the frequency become in coaxial cable.
Figure 27 A describes the power spectral density (PSD) of balanced device input.
Figure 27 B shows the amplitude response of convergent equalizer tap.
Figure 28 A, 28B, 29A and 29B show the loss under different frequency in passband digital video signal relative to skew.
Figure 30 shows the monitor modulatedemodulate in qam demodulator with digital equalizer of some aspects according to the present invention
Adjust device.
Figure 31 describes the Active Analog Filter suitable for equalization base band CVBS of some aspects according to the present invention.
Figure 32 shows the example of the response of the filter in certain embodiments of the invention.
Figure 33 A and 33B are the QPSK planispheres for explaining the rotation in complex plane.
Figure 34 is the block diagram for explaining the phase correction process of some aspects according to the present invention.
Figure 35 describes integral ratio (IP) filter of some aspects according to the present invention.
Figure 36 explains a symbol sent.
Figure 37 A, 37B, 37C and 37D explain the possible recovery symbol of the transmission symbol based on Figure 36.
Figure 38 shows the example of the phase shift in receiving symbol.
Figure 39 shows the example of the transmission planisphere of the typical real and imaginary parts based on frame synchronization symbol.
Figure 40 is the block diagram of the expression phase offset correction device used in some embodiments of the invention.
Figure 41 explanation is for determining the process of reliability related with frame synchronization.
Figure 42 describes certain sides of the balanced device and carrier phase/frequency loop that use in some embodiments of the invention
Face.
Figure 43 shows the sheer used in some embodiments of the invention and phase error detector module.
The complex exponential LUT module that Figure 44 explanation uses in some embodiments of the invention.
Figure 45 A, 45B illustrate the reality of the balanced output in QPSK signal (Figure 45 A) and 16-QAM signal (Figure 45 B)
Portion.
Figure 46 A, 46B and 46C are made when constellation is QPSK (Figure 46 A), 16-QAM (Figure 46 B) and 64-QAM (Figure 46 C)
With the distribution map for the balanced power exported that equalizer convergence is generated in one embodiment of R=58.
Figure 47 explanation restores the example of the constellation of loop module input in balanced device output and carrier phase/frequency.
Figure 48 shows the example of the QAM mapping with the threshold value depicted.
Figure 49 shows the right upper quadrant for all three constellations being covered on the same area.
Figure 50 explanation determines a kind of operation of method of constellation.
Figure 51 A and 51B describe the system for simultaneous transmission SD and HD video of some aspects according to the present invention, should
System has tap or signal interruption.
Figure 52 A and 52B explain the process that some aspects according to the present invention generate frame-synchronizing impulse from noise signal.
Figure 53 is the camera side modulation /demodulation of the indicator with coaxial cable connection of some aspects according to the present invention
The block diagram of device.
The some aspects of Figure 54 explanation automatic gain control loop.
Specific embodiment
The embodiment of the present invention is described in detail referring now to attached drawing, these attached drawings as illustrative example provide so that
Those skilled in that art can be realized the present invention.Obviously, attached drawing and example below is not intended to limit the scope of the present invention
System some or all of described or shown element can enable other embodiments by exchange in the range of single embodiment
Become possible.No matter where, as long as it is convenient, i.e., make to be denoted by the same reference numerals through all attached drawings same or similar
Component.In the case of known elements can be used partly or entirely to realize for certain elements of these embodiments, only to these
Know in component and those parts necessary to the understanding present invention are described, and saves to the other parts of these known elements
It is described in detail and obscures the present invention with unlikely.In the present specification, the embodiment for showing single part is not to be construed as limiting；Phase
Instead, the present invention is directed to cover the other embodiments comprising multiple the same parts, vice versa, unless clearly stating simultaneously herein
It is far from it.In addition, applicant be not intended to make any term in specification or claims be attributed to one it is uncommon or special
Meaning, except non-clearly illustrating, the way it goes.In addition, the present invention covers herein by component current for explaining citation and not
Carry out known equivalent.
Certain embodiments of the present invention, which provides, allows video camera to send high-definition digital video and mark simultaneously on coax
The system and method for clear analog video.High-definition camera is suitable for generating compressed digital video signal and analog baseband signal.
Digital signal is modulated and is sent in the frequency range that the upper frequency with baseband video signal separates.It can be according to the standard of any desired
Analog signal is encoded, including PAL, SECAM and NTSC standard and its deformation.
For the purpose of description, by description using the example of the system of safety chain (SLOC) on coaxial cable.In addition, SLOC
Be generally described as having upstream and downstream signal relative to video camera: position for video camera is in upstream.In the present specification, SLOC system
Example provide downstream high definition (HD) vision signal in the first passband, the upstream audio in the second passband and control signal
And downstream composite video baseband signal (CVBS).It will be appreciated that other passband signals and bandwidth allocation can be used.For example, system
The two-way digital video signal of SD or high definition resolution ratio can be used.
Fig. 3 describes the embodiment of the present invention for explaining the certain working principles of the present invention.The example, which is described, wishes and is about to
HD camera shooting in the system for watching the live video generated by video camera 30 while the video record of high definition version is to 32 DVR
The deployment of machine 30.The example of such system is safety or monitoring system.It can remotely control as described in greater detail below
The function of HD video camera 30.HD video camera 30 is suitable for while generating high-definition signal 332 and simulation CVBS signal 330.In certain realities
It applies in example, high-definition signal 332 and simulation CVBS signal 330 are whens waiting, but if for example handling the delay of unlike signal not
Equalization, then whens they may be substantially equal.In one example, due to conversion expense, CVBS signal 330 be can be
Delay.In another example, compressible high-definition signal 332 and different delays is subjected to based on compression ratio etc..Certain
In embodiment, CVBS 330 and high-definition signal 332 can be synchronous with the common audio signal generated by video camera 30 or be kept therewith
Constant time relationship.
Video camera 30 can be adapted to by adding external component or hardware and software being integrated into video camera 30.In the example
In, safety chain modem (SLOC-T) on coaxial cable is provided in video camera 30.SLOC-T 31 is configured as
The modem that the additives of video camera 30 is integrated or realized using the component for being integrated into video camera 30.SLOC-T 30 permits
Many media feeds are downstream transmitted over the communication channels: as shown, SLOC-T 31 is a kind of equipment, which allows
Multiple signals, the different resolution of the multiple signaling bearer characterization video as produced by video camera 30 are transmitted on coaxial cable 33
Signal.For clear explanation, the SLOC being deployed in sending device (such as video camera 30) is known as SLOC-T herein, and is incited somebody to action
The SLOC being arranged in receiving device (DVR, network switch etc.) is known as SLOC-R.To SLOC-T and SLOC-R equipment
Description will be described in greater detail below.
SLOC-T 31, which can cooperate with other components of video camera 30 and/or can increase, makes the work of video camera 30 in various moulds
Enhancing function under formula.In one example, video camera 30 can produce unpressed HD digital video output and SLOC-T 31
It can provide the ability of compression HD digital video signal.Therefore, SLOC-T 31 can provide the energy other than modulation and demodulation as needed
Power is to enhance the function of host video camera 30.Therefore, several SLOC-T equipment can work in each mode, some of modes
It is provided by example.In one mode, SLOC-T 31 receives the mark of compressed HD vision signal and signal from video camera 30
Clear analog version simultaneously transmits both signals on coaxial cable 33.In another mode, SLOC-T 31 connects from video camera 30
Receive the SD analog version of uncompressed HD vision signal and signal and on coaxial cable 33 together with SD analog signal one
Play the compressed HD digital signal version of transmission.SLOC-T 31 can be transmitted HD digital signal and from the received HD of video camera 30
The SD analog signal that signal derives.
In certain embodiments, SLOC-T 31 generates the output letter transmitted on coaxial cable 33 using frequency division multiplexing
Number.In the example that Fig. 5 is explained, with frequency fCdCarrier wave 53 centered on single frequency range 52 in provide downstream digital letter
Number.Frequency range 52 from be more than base-band analog signal 50 highest frequency f0Position start.The different frequency range 52 is referred to alternatively as letter
Road.Channel 52 can be selected based on the ability of SLOC-T 31, available bandwidth, signal bandwidth and other reasons.In some embodiments
In, channel 52 can be selected according to the compatibility with reception equipment.In one example, signal can be supplied directly to SD electricity
Depending on and channel 52 may be selected to ensure to be properly isolated from baseband signal.It, can also when defining coding using the standard of signal
Multiple frequency ranges in channel 52 are selected based on the standard of digital video transmission.It is conceivable that by using two or more differences
Individual digit signal is transmitted in all parts of channel bearing digital signal.
Any suitable modulation scheme can be used to generate digital signal transmits version.For example, different types of have
Line and wireless connection can be combined with more modulation scheme, such as phase-shift keying (PSK) (PSK), frequency shift keying (FSK), quadrature amplitude modulation
(QAM), orthogonal frequency division multiplexing (OFDM) etc..Modulation scheme is normally based on certain factor selections, these factors include being used for
Characteristic, the frame rate of the vision signal of requirement and the other factors for influencing the available bandwidth in channel 52 of the medium of transmission.
SLOC-R modem 35 may be provided in such as video capture device of DVR 32.SLOC-R modem
35 can receive and handle digital video and CBS signal.Typically, CVBS signal be extracted and be directly passed to display system 33 with
The video image captured by video camera 30 is watched in real time.Display system 33 can be SD monitor, although display system can also
Receive the digital version of received analog signal.In one example, SLOC-R modem 35 can produce analog signal
Digitized version is with data monitor or suitably the computer that is equipped with is combined.The extraction of baseband signal usually uses low pass filtered
What wave device was realized, which can be used analog component or is realized by Digital Signal Processing.It can individually extract
Digital HD signal and the recording portion for providing it to DVR 32.In certain embodiments, number can be compressed in DVR before recording
HD vision signal.In many examples, digital HD video signal is received as compressed digital signal.
In certain embodiments, SLOC-T 31 and SLOC-R 35 is configured to support the transmitted in both directions of signal.In safety
In the example of device, and as referring to Fig. 6 detailed description, video camera 30 may include microphone 614, loudspeaker
612, sensor 616, control interface 618 and other feature for controlling dynamo-electric brake (see Fig. 6).In this example,
SLOC-T 31 and SLOC-R 35 is typically configured to will to control, audio and other data 36 are communicated to video camera 30.
Referring again to Fig. 5, in one embodiment, can be incited somebody to action in the one or more channels 54 for being located at available bandwidth upper end
Upstream data is communicated to video camera.For digital multimedia signal 52, control and audio signal 54 and other data communications
Channel selection can be selected based on signal-to-noise ratio, signaling standard and/or the specialized requirement measured in available bandwidth, channel 52 and 54
It selects.In some embodiments, once establishing the connection of SLOC-T 31 and SLOC-R 35 using training sequence, that is, letter has been determined
Road configuration, bandwidth and signal-to-noise ratio.Typically, predetermined or negotiated channel signalling capability is determined, using training sequence with selection
It is used for transmission the channel 52 of digital video and determines the available bandwidth in selected channel 52.The characteristic of selected channel 52 can be used for setting
Determine the compression level of digital video signal.
In certain embodiments, stream signal 54 includes the signal that can control the content of 50 signal of downstream 52 and base band.Example
Such as, camera optics device 600 can provide the flake visual field of the position monitored by video camera 60 and can control camera processes device
To select a part of image being used for transmission as baseband signal 50.Typically, downstream digital signal 52, which can provide, is recorded in DVR
Complete image that is upper or Gong being further processed.Baseband signal 50 can receive area of the baseband signal 50 with real-time monitoring under supervision
Domain.Baseband signal 50 may include adjusted image, the visual effect which is formed by fish eye lens.Base band letter
Numbers 50 observer can make the visual field in the fish-eye ken by selecting new a part to be captured image and observe
It is mobile.For example, observer can request " to right translation " so that the ken moves right.The data transmitted in stream signal 54 then make
Camera processes device extracts and processes the requirement part of the ken.In certain embodiments, make to include the view in baseband signal 50
The mobile request in domain can cause the physics of video camera 60 mobile.Therefore, the control data in stream signal 54 may influence base band
50 and both 52 signals of downstream digital content.
In certain embodiments, downstream audio can be used as the part of HD digital video signal and/or as CVBS signal
Fractional transmission.Some lower swimming signalings can be carried in individual dedicated channel (not shown).In certain embodiments, with video camera
Out-of-band communication method can be used to realize for 30 upstream communication, including for example using wired or wireless network.In some embodiments
In, it is contemplated that it wirelessly sends downstream digital signal 52 and alternatively or additionally selects.Therefore, it is being wirelessly transmitted 54 He of upstream
While some combinations in downstream 52, coaxial cable transmission base band 50 can be passed through.Typically, upstream data 54 includes downstream
52 and base band 50 control signal, regardless of transmission method why.
In certain embodiments, cable 33 can be supplied directly to display system 33 and simulate SD video to show.SD
Monitor or display 33 generally include to allow the filter circuit selected between baseband signal and the TV channel of classical modulation.Knot
Fruit, monitor 33 can drop the carrier signal of high-frequency digital coding.If defined in the channel that standard defines and using standard
Digital encoding scheme transmission digital video signal, then DVR 32 can also receive digital video signal without extra process.
Decoded HD digital video and other signals by the signal generated of SLOC-T 31 and are supplied to DVR by the decoding of SLOC-R 35
32.SLOC-R 35 can also encode for transmitting to video camera 30 control data, audio data and other data.
Referring now to Fig. 4, the embodiment of the present invention is provided, which explains certain working principles of the invention.Fig. 4 is retouched
Draw an example, the example based on while requiring to watch the live video generated by video camera 40 by the network switch 44 in net
The system of HD video version is provided on network.In one example, HD video feed is captured and is regarded using internal or external IP
Frequency server is streamed.HD video camera 40 is typically suitable for generating high-definition signal and Analog Baseband vision signal simultaneously.It can pass through
Hardware and software is integrated into video camera 40 to be adapted to video camera 40, such as SLOC-T 400 by addition external component.SLOC-T
400 can mode identical with SLOC-T 31 shown in Fig. 3 operate.However, SLOC-T 400 can be configured in favor of in net
The mode of digital video signal is forwarded to encode digital video signal on network.For example, SLOC-T 400 can be according to IP video
The streaming format that server is supported programs or to be separately configured to provide for digital video signal.
The multiplex video signal sent by digital camera 40 can be received by the network switch 44, the network exchange
Machine 44 is optionally equipped with SLOC-R 440.Extractable base band SD analog signal simultaneously provides it to display 43.In certain realities
It applies in example, SLOC-R 440 can extract digital high-definition video signal and using enough bandwidth with carrying digital HD video signal
Suitable networks forward it to video server or other network equipments.Digital HD video signal may include compressed HD view
Frequency signal.In certain embodiments, the digital high-definition signal extracted by SLOC-R 440 is compressed or is further compressed to forward
To video server or other network equipments.SLOC-R 440 may include for record and/or re-modulation digital high-definition signal with
In the hardware and software of transmission over networks；Such as SLOC-R 440 can produce the H-264 signal of coding to transmit over ethernet.
Referring now to Fig. 6, certain embodiments of the present invention provides the enhancing ability for being suitable for security system.Discribed
In example, video camera 60 includes modem SLOC-T 606 and processor, and processor is configured and is adapted to according to this hair
Bright some aspects are provided through digitally coded multi-media signal.The combination of optical device 600 and imaging sensor 602 can be used
Capture image sequence, this combination may include the combination of lens system and ccd sensor known to those skilled in the art.
Processor 604 usually receives scanning signal 603 from imaging sensor 602, and described image sensor 602 is provided according to requiring or in advance
Define frame rate captured image sequence.
In some embodiments, imaging sensor 602 may include that will characterize by one or more sensors captured image
The analog signal that scanned converted and generate the hardware and logic of digital video signal.For example, imaging sensor 602 can wrap
Include RGB (red, green, blue) sensor and imaging sensor 602 can the output of inter-process RGB sensor to generate through digital coding
Colour-video signal as its export 603.In other embodiments, processor 604 can be pre-processed from imaging sensor 602
Signal 603 to obtain raw digital video signal.It is either obtained from inside or received from imaging sensor 602, it is former
Beginning digital video all can be by processor 604 for further processing to obtain initial HD digital video signal.Simulate standard definition signal
It can be obtained by processing raw digital video signal, the output 603 of sensor 602 or initial HD digital video signal.Processing
Then device 604 can be formatted initial HD digital video signal to obtain the one or more for meeting broadcast and other standards
HD digital video signal.For example, processor 604 can produce the signal for meeting the broadcasting video standard of such as ATSC and DVB standard.
Processor 604 can additionally compressed digital video signals.
Camera processes device 604 may include the combination of commercially available component and custom hardware and software.In one example, it handles
Device may include microprocessor, digital signal processor, microcontroller, sequencer and other with memory combination and support to hold
One or more of row series of steps, instruction and/or programming device of logic of program.Storage 610 can be used to store
Computer-readable instruction executes some or all functions described in this application when executing the instruction.Camera processes device
604 may include some built-in or " hard coded " processes, these processes can be used to construct certain embodiments of the present invention.Storage
610 can also be used to program buffer and/or maintain configuration information.In certain embodiments, storage 610 can be used for storing by taking the photograph
The videograph that camera 60 captures.Therefore, 610 usable volatile and nonvolatile memories, CD and disk, removable electricity are stored
Erasable memory, USB memory driver and other semiconductors, electromagnetism and light storage device are realized.
Signal 605 include be supplied to by processor 604 SLOC-T 606 vision signal and from route 62 receive and by
SLOC-T 606 is transmitted to upstream control, audio and the other upstream informations of processor 604.It can be by voice frequency relay to loudspeaking
Upstream audio-frequency information is decoded by processor 604 before device, energy converter or other audio output systems 612, handle and/or
It formats.Processor can amplify audio signal or can use individual amplifier in audio output part 612.Upstream control can
Including optics control 601 and the signal of external equipment is controlled, which usually passes through control interface 618 and provide.External equipment can
Including the motor or actuator for making video camera 60 translate, rotate or to be separately orientated.Optics controls signal 601 and outside
Control signal 618 may be in response to be generated by the predefined order of remote control system.For example, remote subscriber can manipulate a rocking bar, this is shaken
Bar generates a series of coded commands explained by camera processes device 604, to indicate " deasil to rotate in horizontal plane
90 degree of video camera ", and a series of pulses can be by being sent to the stepping electricity axially mounted relative to video camera 60 by processor 604
Motivation makes a response, and thus this series of pulses makes video camera 60 carry out desired rotation around its vertical axis.Similar order can
Adjust focus, scaling and the aperture of optical device 600.
In another example, it can be controlled in information in upstream and instruction and data is provided, upstream control information can be used for controlling
The function of processor 604 and/or sensor 602 processed.The instruction and data can be used for selecting a certain area in 60 ken of video camera
Domain in one or more downstream visual signals to be encoded.In certain embodiments, processor and sensor cooperation are to mention
For one or more virtual cameras, these virtual cameras can be remotely steerable to specify portion to be encoded in the ken
Point, from there through empty translation, scaling and the inclination function that can be operated in the practicality visual that the optical device by video camera 60 determines
It can select these parts.In certain embodiments, processor 604 can extraly make video camera physics mobile, thus expand flat
It moves, the range of inclination and zoom function.
In at least some embodiments, conception carries CVBS and digital signal respectively to be captured by imaging sensor 602
The part of image.These image sections can be overlapped or from the different zones formed in the ken provided by camera lens 600.Separately
Outside, in certain embodiments, it additional cameras 60 and/or additional image sensor 602 that can be used can use the ken to expand.Example
Such as, it is expected that configuring multiple video cameras to obtain the panorama in region (360 °) view.One or more processors 604 can provide representative
The analog and digital signal of view or a part of view.In one embodiment, it can be provided in the digital signal that DVR is recorded
Complete panoramic view, while CVBS signal can provide selectable view in panorama.The usable scaling of selectable view,
Translation and other controls are controlled.In another example, CVBS and digital signal can provide the public or different of panoramic view
Part and these parts are can be by remote observers' independent control.
Fig. 7 is shown in secure digital video recording system 70 using similar with SLOC-R 35 described in Fig. 3
The example of SLOC-R 700.System 70 includes SLOC-R 700, the DVR processor for being connected to peripheral equipment 710,712 and 714
702, analog video decoder device 704, digital video decoder 708 and HD digital display processor 706.As described above, SLOC-R
700 receive the decode the signal from coaxial cable 72, which generally includes simulation SD vision signal and HD digital video
Signal.SLOC-R 700 also transmits upstream audio and control signal by coaxial cable 72.SLOC-R is usually in input signal 72
It is middle to separate with HD digital video signal simulation CVBS signal, digital video signal 703 is supplied to processor 702 and by CVBS
Signal 701 is supplied to SD monitor 74 as the real-time feeding from video camera 60 shown in fig. 6.SLOC-R 700 is optionally
Analog Baseband vision signal 701 is supplied to analog video decoder device 704, which handles signal to produce
Raw number SD vision signal 705.Video-stream processor 706 multiplexes digital standard definition signal 705 and regards from stored HD number
It derived signal 707 and makes a choice between both signals in frequency playback.Video-stream processor can provide can be by HD TV
Or the selected signal of the displayable format of monitor 76.
DVR processor 702 receives digital HD video signal 703 and at least part of optionally stored signal is used as by taking the photograph
The recording for the video that camera 60 captures.Recording can be stored in local hard drive 714, be stored in networking memory (not
Show) on or be stored in by network interface 710 and/or USB/ firewire or other local bus 712 connection other optical, electromagnetics
Or in semiconductor storage.The video recorded can further be compressed to save memory space.Digital video can be used in DVR processor
The video of the retrieval recording of decoder 708 simultaneously provides playback signal 707.
Fig. 8 shows the showing using the SLOC-R 800 similar with SLOC-R 440 shown in Fig. 4 in networking safety equipment 80
Example.Equipment 80 includes SLOC-R 800 and the network exchange processor 802 for being usually connected to ... through the network IP video server 86.
As described above, SLOC-R 800 receives the decode the signal from coaxial cable 82, which generally includes simulation SD video
Signal and HD digital video signal.SLOC-R 800 transmits upstream audio and control signal alternately through coaxial cable 82.
SLOC-R separates simulation CVBS signal with HD digital video signal usually in input signal 82, by digital video signal 803
It is supplied to processor 802 and CVBS signal 801 is supplied to SD monitor 84 as from the real-time of video camera 60 shown in Fig. 6
Feeding.In certain embodiments, SLOC-R 80 may include component 804,806 etc., with digitize CVBS signal 801 with such as
The digital display of high-clear display 85 is combined, equally as the real-time feeding from video camera 60 shown in fig. 6.However high-ranking military officer
Meeting, appropriately configured display equipment or calculating equipment can receive CVBS signal 801 and executes the digitlization of signal.At network exchange
Reason device 802 receives digital HD video signal 803 and optionally transmits signals to network video server 86, then the network video
Frequency server 86 can maintain the recording of the video captured by video camera 60.Digital HD video signal 803 can be transmitted to video clothes
It is further compressed before business device 86.
Referring again to Fig. 5 and Fig. 6, certain embodiments of the present invention allows to select base-band analog signal 50 under as needed
Swim the content of signal 52.In one example, baseband signal 50 and downstream signal 52 include both same image, the former is mould
Quasi- form and the latter is through digitally coded.Digital picture can be optionally and selectively with compression and uncompressed form, with SD
It is sent with high definition and with full motion or reduced frame rate.In another example, baseband signal 50 is provided by image sensing
The a part for the complete image that device 602 captures, while downstream signal 52 carries complete image.In another example, baseband signal
50 provide the complete image provided by imaging sensor, while downstream includes a part of complete image.As a result, visualizing one kind
The system configured very well, it allows the user of digital camera from the wide scope for showing, recording and transmitting video image
It makes a choice in option.
The analog balanced of baseband signal
Certain embodiments of the present invention includes the system and method for improving the high frequency shuffle effect in cable, aforementioned height
Frequency shuffle effect will cause higher frequency decay with the increase of cable length.Base band mould is made by this skew that cable introduces
Quasi- video and the deterioration of passband digital video signal, this deterioration are further serious with cable length increase.However, of the invention
Some embodiments usually provide balanced device in digital receiver, which removes the skew on digital passband signal, allow
Send the reliable decoding of symbol.
Certain embodiments of the present invention improves the performance of system and device including those aforementioned systems, and wherein base band regards
Frequency signal can be combined with the digital representation of baseband video signal and control signal, thus be allowed in such as coaxial cable (" coaxial ")
Unit cable on transmit.Fig. 3 and Fig. 4, which is shown, provides the embodiment of SLOC system, and one kind that Fig. 5 shows SLOC system is feasible
Modulation scheme.By taking Fig. 3 as an example, HD video camera 30 provides the output 332 comprising compressed digital HD video and includes mould
The auxiliary camera output 330 of quasi- SD (SD) CVBS.Compressed HD vision signal 332 utilizes SLOC camera side modulatedemodulate
Device 31 is adjusted to be modulated to passband 52, which includes QAM modulation device, which provides
Modulated signal, the signal are combined with baseband analog CVBS signal 330.Combined signal on coaxial cable 33 downstream
Transmission, typically for up to 300 meters or longer distance.In monitor side, SLOC monitor side modem 35 will represent base band
The signal of CVBS signal 330 is isolated from the signal for representing passband downstream visual signal 332.The signal of characterization CVBS is fed to
SD display 34 is used for no-delay real-time viewing.Upper passband downstream signal is demodulated with qam demodulator, the output quilt of qam demodulator
It is fed to host-processor and DVR32, DVR32 supports real-time (although may slightly be delayed) HD viewing on monitor 34 and non-
Real-time HD playback for watching in the future.
In this example, according to for example needing to provide upstream communication by IP agreement.Upstream communication can extraly be used
Audio and camera control signal 334 are sent to video camera 30 from monitor side.Usually, the bit of stream signal
Rate --- and therefore required bandwidth --- bit rate and bandwidth needed for being typically well below downstream passband signal.Monitor side
SLOC modem 35 includes QAM modulation device, and the QAM modulation device is by IP signal modulation to upstream passband 54.As Fig. 5 is retouched
It draws, upstream passband 54 and downstream passband 52 are located at different spectral position.In camera side, SLOC modem 31 includes using
In the qam demodulator for receiving stream signal.This method provides several advantages for being better than existing system and method, comprising:
(1) increase working range-increase distance.
(2) existing infrastructure can be used and reuse coaxial cable and carry out deployment system.
(3) low delay availability, real-time (fact) video.
(4) live CVBS video and HD video can be watched in dividually point.
Figure 21 is the rough schematic view for showing the additional detail of SLOC camera side modem 49 of Fig. 4.It is taken the photograph to HD
The IP connection of camera 2100 is interfaced to QAM modulation device 212 and qam demodulator 214 by Media Independent Interface (MII) module 210.
In one example, MII 210 follows 802.3 standard of IEEE.QAM modulation device 212 is worked using principles well-known with by baseband I P
Data flow 2100 is converted into passband QAM symbol 2120.These symbols and base-band CVBS signal 2160 are summed 216 and then will
It is fed to duplexer 218.Duplexer 218 can be bidirectional analog equipment, it is by combined base band and lower passband downstream signal
2162 are transferred to coaxial cable and receive upper passband stream signal 2140 from coaxial cable and be fed into qam demodulator 214.
Qam demodulator 214 is worked usually using principles well-known to demodulate from the received upper passband stream signal 2140 in monitor side and incite somebody to action
Base band data is exported to MII interface 210.
Figure 22 is the rough schematic view for showing the additional detail of SLOC monitor side modem 45 of Fig. 4.Duplexer
The 220 base band CVBS combined from coaxial cable reception downstream and lower passband IP signal 2200 simultaneously pass through low pass (LP) and high pass (HP)
Signal is divided into component elements 2201-2203 by filtering.CVBS signal 2201 can be delivered directly to SD monitor or other
Show equipment.Low pass band signal 220 can be fed to qam demodulator 222, which presents to MII interface module 226
It send.Duplexer can also receive high pass band signal 2203 from QAM modulation device 224 and the stream signal can be transferred to coaxial cable.
QAM modulation device 222 usually obtains its input from MII interface 226, MII interface 226 may connect to support the host of IP agreement/
DVR。
Coaxial cable typically exhibits significant high frequency slip characteristics, which increases meeting with cable length
Cause higher frequency decay.This " skew " is of great significance in the frequency range of passband signal and may cause significant code
Between interfere (ISI).Digital equalising may be needed to allow qam demodulator 222 correctly to restore transmitted data.
Base band to passband is modulated
Figure 23 more specifically shows camera side base band to passband QAM modulation device 212 (Figure 21).Number from MII 210
It is received according to by FEC encoder/mapper 2300, which uses for example cascade Reed-Solomon
Error protection data are added to from the received data flow of MII 210 by coding, byte-interleaved and/or trellis coding.Mapper/volume
Data multiplex is resolved into stream 2300 and 2302 by code device 2300, wherein the bit group of the given size of each stream is in real axis and the imaginary axis
Direction respectively represents QAM symbol amplitude level.Transmission QAM pulse through being isolated is given by the following formula:
Wherein dR,mAnd dI,mIt is the real and imaginary parts for being determined by two independent message streams and being respectively indicated multiple QAM symbol,
Wherein index of the m=1...M as two dimension QAM radix constellation, wherein M is modulated carrier frequencies and q (t) is square-root raised-cosine arteries and veins
Rush function.
The transmission QAM pulse s (t) of one continuous series is with rate FS=1/TSPass through the multipath channel with noise.Therefore, exist
Reception signal to the input side of QAM receiver is provided by r (t)=s (t) * c (t)+v (t), and wherein * indicates convolution, and c (t) is
Channel impulse response, and v (t) is additive white Gaussian noise.Therefore:
Wherein d [n] is multiple transmit code element, f0And θ0It is that receiver pass-band is opposite to base band demodulator local oscillator respectively
In the frequency shift (FS) and phase offset of transmitter, thus fLO=fc-f0。
Passband is to base band demodulator
Figure 24 A illustrates in greater detail monitor side passband to base band qam demodulator 222 (Figure 22).Signal r (t) can be from same
Shaft cable receives, such as to be higher than the polydispersity index (see 240) of chip rate, thus obtains sampled signal r (nTsamp)。
After sampling:
Then, after down conversion, with chip rate 1/TSIt samples again and matched filtering obtains:
Wherein v ' [k] is sampled multiple filter noise, it is assumed that any ISI is attributable simply to channel impulse response c, because of arteries and veins
Punching forming and matched filtering q are combined with perfect chip rate sampling timing.
Balanced device and carrier phase/frequency ring
Discuss the digital equalizer and carrier phase/frequency loop of Figure 24 A in more detail referring to Figure 25.Signal x [k]
Into adaptive digital balanced device 250, which may include being made for compensating by channel impulse response c
At skew linear digital filter.One or more known methods including LMS algorithm can be used to realize tap-weights
Adjustment.Balanced device outputs it y [k] and two-dimentional (2D) sheer is adjudicatedPhase-rotated version make comparisons to create use
In the error signal for the update collection for calculating filter tap weights.LMS algorithm can operate as follows:
Enable: x [k] indicates the balanced device input vector of N length, and
Y [k] indicates balanced device output vector gH[k] x [k],
Wherein gH[k] is the equalizer tap weights vector of N length and subscript H indicates that conjugation exchanges (Hermit conjugation).
G [k+1]=g [k] -2 μ x [k] e*[k],
Wherein μ is small step parameter and subscript * indicates complex conjugate.
In order to eliminate the influence of passband cable skew, after convergence, LMS equalizer tap can be similar to channel impulse response
The inverse of c.
The independently real and imaginary parts of cutting z [k] and the output of 2-D sheer 252 It is the d [k] of original transmission
Estimation.Phase error detection module 258 receive z [k] andAnd form phase error signal
Low pass (LP) filter 256 can be integral scale filter, the integral scale filter allow loop phase calibration deviate and
Frequency shift (FS).The output of low-pass filter 256 is fed to subdivision and founds voltage controlled oscillator (VCO) 254, and the voltage controlled oscillator 254 is defeated
θ is corrected outoAnd foThe complex phase position of the two/frequency correction factor e-jθ[k].VCO 254 also provides output (e+jθ[k]), the output is " no
Correction " slice outputSo that it can be used for exporting the error signal updated for equalizer tap.Since balanced device works
At x [k], therefore this is typically required.See also Figure 24 A, balanced device output z [k] is fed to symbol de-mapper, should
The real number and imaginary number level translation that symbol de-mapper will test are at bit group.Then fec decoder device executes Veterbi decoding,
Byte deinterleaves and/or Reed-Solomon decoding is to correct the error of reception bit and send the data obtained to MII interface.
The influence of cable length
Received vision signal due to being attributable to the frequency of certain features of cable can undergo decaying because becoming.For begging for
By purpose, the example of coaxial cable is described.The severity --- being frequently referred to as skew --- of decaying generally depends on electricity
Cable type and cable length.Figure 26 A and 26B are shown because becoming in the frequency of type of cable RG6 and RG59 for various length
Decaying.As can be seen that skew is equivalent to multipath distortion, wherein additional path and main path have minimum delay extension.With
Skew increases, and the number of important multipath component and its respective gain also increase.Multipath distortion causes to receive the ISI in signal simultaneously
It therefore may seriously degrading transmission reliability.In a digital signal, these damages can be removed using balanced device in receivers
Evil.The power spectral density (PSD) of balanced device input is shown respectively in Figure 27 A and 27B and the amplitude of convergent equalizer tap is rung
It answers.Specifically, Figure 27 A shows the equilibrium after the RG6 cable by 2000 feet transmits under 15.98MHz carrier frequency
The PSD (showing both band connection frequency and opposite baseband frequency) of device input, and Figure 27 B shows convergent digital equalizer tap
Amplitude response.
Certain embodiments of the present invention includes digital equalizer, the digital equalizer can eliminate by cable introduce skew,
It removes the ISI in passband signal and realizes the reliable decoding of transmission data.As cable length increases, digital equalizer can be used
Come reliably with well known numerical data forward error guard method (such as cascade Reed-Solomon coding and trellis coding)
Receive the digital passband signal in monitor side.However, cable skew can also adversely affect baseband analog CVBS signal
High-frequency, this can reduce the acutance for the picture watched in monitor side and the intensity of color.Therefore, some embodiments provide
Sef-adapting filter, such as analog equalizer, the sef-adapting filter can be applied to CVBS signal in monitor side to compensate base
Cable skew with place.Some embodiments estimate the skew amount at base band using passband digital equalizer, and then select one
In group baseband analog filter it is appropriate one to be applied to the received CVBS signal of institute.
The efficient estimation of passband skew
When estimating the skew in signal frequency range, the skew when quantifying with dB in the PSD of input signal, which may be selected, to be connect
The frequency range of near-linear.Therefore, in the input of base-band digital balanced device therefore the frequency of -2.67MHz to 2.67MHz will correspond to passband
The frequency of 13.31MHz and 18.65MHz in input signal provides a suitable range.As shown in fig. 26, from 13.31MHz to
18.65MHz is about 3.7dB to the skew of 2000 feet of RG-6.Convergent digital equalizer filter is come from order to estimate
Following calculation can be performed in the skew in terms of dB of tap:
Wherein G [k] is the DFT of the convergent equalizer filter tap of time domain, and k1And k2Specific frequency band corresponding to DFT.
Since the digital equalising of Figure 25 can be realized by convolution, in order to estimate given k1And k2Skew, it usually needs
FFT (or n times may be made to two points and multiply and be added with again).That is,
Wherein g (n)=gR(n)+igI(n), n=0,1...N-1 is that N time-domain equalizer tap is (interdependent with time index
Property is ignored).Note that 1/N scalar is unwanted in this is calculated.G (k can be directed to2) execute similar calculating.However,
Calculating can be substantially reduced by carefully selecting frequency band.By enabling k1=N/4, this corresponds to the frequency of 2.67MHz, equation
(2) complex exponential in is significantly simplified:
Read group total can be used to go out for the real and imaginary parts of filter freguency response:
Finally, the power under the frequency band are as follows:
By making k1=N/4, power calculation are significantly simplified.Similarly, if k1=3N/4 corresponds to -2.67MHz
Frequency, then complex exponential is significantly simplified again.
Real and imaginary parts are calculated as:
And power is calculated as described above | G [k1]|2.In Figure 27 B, in the amplitude response of convergent filter tap
The optimum SNR of skew (as unit of dB) and 64QAM signal and tap noise evenly approximately linear upwards.In addition, when with
When such mode calculates,This very close practical skew 3.7dB in the frequency range.
Passband skew estimation to base band CVBS skew corrected
After for digital video signal estimation passband skew, it can be selected from one in M different filters suitable
Suitable baseband analog filter.As can be seen that the passband skew of digital video signal frequency range estimated will indicate base band CVBS
Then crooked severity in signal can be used analog filter roughly to correct the skew.In Figure 28 A, show for RG-
6, the digital video signal frequency of RG-11, RG-59 with those of RG-174 and similar length electricity from 13.31MHz to 18.65MHz
Skew in section.Figure 28 A, which is shown, to be believed for RG-6, RG-11, RG-59 and RG-174 type of cable relative to passband digital video
Loss under the 3.58MHz of skew in number.Figure 28 B shows the loss at 6MHz.It is observed that in 3.58MHz and
Loss under 6MHz is roughly the same for all four type of cable for giving skew.Figure 29 A is shown for RG-6, RG-
11, RG-59 and RG-174 type of cable is relative to the loss under the 3.58MHz of the skew in passband digital video signal.Figure 29 B
Loss at 6MHz is shown.It is observed that the loss at 3.58MHz and 6MHz is for giving crooked all four electricity
Cable type is roughly the same.
Since the passband skew estimated is unique available information about cable frequencies response, ideal scene is
Frequency response of the cable under base band (CVBS signal frequency range) is related with the skew of passband digital signal in a known way, regardless of electricity
How are cable type or length.Figure 28 B, 29A and 29B confirmed this feelings in the frequency response under DC, 3.58MHz and 6MHz
Shape.For example, at the 1.5dB skew in passband digital video signal, for loss of all four cables at DC, in color
Loss under carrier wave (3.58MHz) and the loss at 6MHz are about 0.68dB, 4.1dB and 5.3dB respectively.Therefore, no
Pipe is caused from 275 feet of RG-174,750 feet of RG-59,825 feet of RG-6 or 1825 foot of RG-11
The passband skew of 1.5dB, same analog filter will eliminate the base band skew of CVBS signal.
An example for the algorithm from the suitable analog filter of one group of M filter selection is as follows:
Inputs:| G [k1]|2, | G [k2]|2
Rn=αn|G[k1]|2, for n=0,1 ..., M.
Select analog filter L.
end if
Pay attention to α0=1；αnOther value < 1 and select them so that displacement addition be enough to calculate Rn.Therefore, usually more
Change plan 24A monitor side qam demodulator so that passband qam demodulator digital equalizer provide a signal, signal behavior M
Simulate one in the response of CVBS filter.Figure 24 B shows the change part of monitor side qam demodulator, wherein analog filtering
Device is exported from the digital equalizer selection to be worked according to aforementioned algorism.Figure 30 shows complete monitor side modem,
Filter selection signal 305 is supplied to CVBS analog equalizer 302 by the digital equalizer in qam demodulator 304.
One example of the Active Analog Filter suitable for equalization base band CVBS signal is illustrated in Figure 31.In this example, M
=3, thus there are 4 kinds of possible filtering selections.By one in M+1 switch in closure switch module 310 and thus
Each RC being attached thereto is set to select to close the filter response needed to being successively grounded.Possible filter response is shown in Figure 32.
Those skilled in that art will be appreciated that present invention can apply to using other passband modulation and forward error correction methods
Digital communication system.Those skilled in that art will also be appreciated that usable passband digital equalizer tap-weights vector g [n]
FFT in more than two points other types for coming for CVBS signal behavior analog filter, and passband signal being used
Digital equalizer designs, including frequency domain equalizer, wherein G1[k] and G2The value of [k] has been used as a part of equalization process to calculate
Out.In addition, the known equalizer tap weights calculation method in addition to LMS, such as RLS can be used.
In certain embodiments, there is the CVBS analog filter that response may be selected form other than the above can be used.Together
The form of digital filter can be used in the balanced device of sample, CVBS signal, samples before the equalization to CVBS in this case
And digitlization.In this case, according to described for select one identical algorithms in the response of M analog filter from
The tap-weights of the predetermined concentration selection digital filter of M tap-weights vector.
Framing in digital communication system
Digit data stream usually has some type of frame structure, so that the data are organized into the bit group of uniform size
Or byte group.The frame of error correcting code word length or so will be woven in group using any system of block-based forward error correction (FEC).Together
Sample, if system fights impulsive noise using interweaving, frame structure will consider that interleaver parameter configures.If system makes
Flat Spectra is obtained with randomizing data, then the pseudo-random sequence utilized can be synchronous with frame structure, the weight when every frame starts
It is new to start.
For RF digital communication system, it is synchronous and balanced with chip clock that receiver generally has to acquirement carrier wave first.So
It can restore transmitted data afterwards.But in order to understand this incoming data flow, receiver must be also same with the frame structure
Step.In other words, receiver must be known by error correction code word since where and wherein terminate.It must also can make such as to deinterleave
The synchronous interleaver operation to match transmitter of the receiver module of device so as to the bit to deinterleave or byte by just
It really sorts and derandomized device, to match the starting point for the pseudo-random sequence in transmitter so that frequency spectrum becomes flat
It is smooth.
Legacy system is provided frequently by the head or tail portion that the known pattern of the symbol of regular length is attached to frame
Receiver frame is synchronous.The every frame of the identical patterns repeatedly, and it is often by 2 grades (i.e. two with advantageous auto correlation characteristic
System) pseudo-random sequence composition.This means that although sequence auto-correlation under zero offset generates a larger value with itself,
The autocorrelation value (secondary lobe) is very small if deviating as non-zero.In addition, the frame synchronization sequence will be related to random symbol to be produced
A raw smaller value.Therefore, if the storage version of receiver frame synchronization pattern executes the association of input symbols, should it is expected only
A larger value is generated in the accurate starting position of each frame.Then receiver can readily determine that the initial point of each frame.
The example of frame structure
Referring to Fig. 9, ATSC DTV (DTV) ground transmission standard used for 1996 provides data with what frame transmitted and is
System.Each frame 90 includes 313 sections, and each section includes 832 symbols, therefore each frame has 260416 codes in total
Member.Four symbols of beginning in each section are segment sync symbols 92, these symbols constitute sequence [+5, -5, -5 ,+5].Often
The first section in a frame is the frame synchronization section 94 with 312 data segments 96,98.Referring now to Figure 10, frame synchronization area
Section 94 has segment sync 100,511 symbol pseudo noise (PN511) sequences 101,63 symbol pseudo noise (PN63) sequences
Column 102, the 2nd PN63 sequence 203 and the 3rd PN63 sequence 104.It is the 24 mode symbols 105 that indicating mode is 8VSB later.In advance
106 configuration frame sync segment 94 of code symbols 107 and reserved symbol.Segment sync 100 and 101 symbol of PN511 are to receiver
A priori known and can be used to obtain frame synchronization by correlation technique.All aforementioned symbols are originated from collection {+5, -5 }.The section
Last 12 symbols from collection { -7-5-3-1+1+3+5+7 }, and be the pair of last 12 symbols of last data field
This.They are referred to as pre-coded symbol (not discussing herein).
Turning also now to Figure 11,312 section subsequent for each of field --- they are referred to as data segments --- is four
828 symbols 32 after a segment sync symbols 30 are formed from individual 207 byte (1657 bit) Reed-Solomon (RS)
Code word, this be by taking 2 bits every time, by their trellis codings at 3 bits and then by 3 bit map of per unit to come from collection-
7-5-3-1+1+3+5+7 } 8 grades of symbols complete.
Another example of framing is found in ISDB-T system in digital communication systems.It is different from single carrier ATSC system,
ISDB-T is the multicarrier system using Coded Orthogonal Frequency Division Multiplexing (COFDM).For example, the mode 1 of ISDB-T uses 1404
Carrier wave.One frame includes that 204 COFDM symbols are constituted, and each COFDM symbol is regarded as 1404 independent QAM symbols
Combination, have one for each carrier wave.Therefore, which is made of 204x 1404=286, the combination of 416QAM symbol.Its
In, 254,592 symbols are data, and 31,824 symbols include pilot frequency information (can be used for frame synchronization) and are dissipated with known pattern
Pattern information of the cloth in frame.
The simplified illustration of frame configuration is for Figure 12.As can be seen that pilot tone and pattern information are dispersed in frame with known pattern
Around.The system, which has, utilizes three kinds of different qam constellations --- the mode of QPSK, 16QAM and 64QAM.It is also based on list
Female code of perforation supports five kinds of different trellis coding rates (1/2,2/3,3/4,5/6,7/8).This well known technology makes
Single Viterbi decoder is constructed in receiver becomes very economical, and the Viterbi decoder is easy to adjust in designated code
Institute be decoded there are five types of code.
Before transmitter side carries out trellis coding, data are formed as 204 bytes (1632 bit) long RS block.Although in every frame
COFDM number of symbols it is always constant, however the number of the RS block in every frame changes with institute's lectotype, but most significantly,
The number always integer.Once establishing frame synchronization and known trellis coding rate, this allows for easy RS block in receiver synchronous.
To realize this, for all modes, the number of the data bit of every frame must can be divided equally by 1632 before trellis coding.
Table 1 shows the number of the data bit of every frame for all modes (combination of qam constellation and trellis coding rate).
In each case a, the number of every frame data bit can divide equally (data bit means the bit before trellis coding) by 1632.
Table 1: for every frame data bit of ISDB-T
Certain embodiments of the present invention provides a kind of framing structure for the modulating system for digital communication system.Tool
Say to body, provide can apply to include the security system of those described above signaling system and method.Convolutional byte interleaver interweaves
Data frame, wherein interleaver is synchronous with frame structure and randomizer can be configured to generate from the data frame of intertexture through being randomized
Data frame.In one example, the trellis coded modulation device of perforation works under optional code rate, and the modulator is from through random
The data frame of trellis coding is generated in the data frame of change.Bit group in the data frame of trellis coding is mapped to modulation by QAM mapper
Thus symbol provides frame and synchronizer through mapping for synchronous grouping and adds to the frame through mapping.The trellis coded modulation device of perforated
It can be bypassed as needed with optimization net bit rate under the conditions of obtaining various white noises, thus allow the performance of system excellent
Change.
In certain embodiments, novel frame structure is provided in carrier wave communication system.In the beginning of frame at zero offset
The auto-correlation of the known pattern of the regular length symbol at end or end generates a larger value, related if the offset is non-zero
It is very small to be worth (secondary lobe).However, the frame synchronization sequence is related to random symbol will to form a smaller value.Therefore, receiver can
The correlation of incoming symbol is executed, with the storage version of frame synchronization pattern to obtain in the larger of the accurate starting position of each frame
Value, this makes receiver determine the starting point of each frame.Under the either mode that communication system can work in various modes, and it can make
With the various combinations of symbol constellations, trellis code and interlacing pattern.Receiver must identify and understand mode successfully to restore to be passed
Defeated data.For this purpose, frame synchronization pattern can be added to additional mode symbol.These mode symbols can use correlation technique can
It is received by ground, because they are that every frame repeats to send.They can be made more to these mode code primitive encodings by using block code
It is strong.
A kind of frame structure of some aspects, which utilizes, according to the present invention is similar to those perforation trellis codings used in ISDB-T
It is combined with qam constellation.The code element number of each frame can be the RS grouping number of variable integer and each frame depending on mode
Regardless of why mode is all constant integer.This arrangement simplifies the processing of the receiver of such as derandomized device and deinterleaver
The design of module, because what the RS grouping number of each frame was always fixed.In the legacy system of such as ISDB-T, the code of every frame
First number is constant, and the RS grouping number of every frame is the variable integer depending on mode.The transmitter that referring to Fig.1 3 are described
The example of framework describes frame, and the transmitter architecture is some aspects building according to the present invention.
RS encoder 1300 receives byte data 1301 and the external frame synchronizing signal generated, frame synchronizing signal instruction
The beginning of every group of 315 Reed-Solomon grouping 1322.As shown in figure 14, each grouping 140 includes 207 bytes, wherein
20 bytes are parity bytes 142.This 315 Reed-Solomon are grouped to form the forward error correction comprising 62205 bytes
(FEC) data frame 1322.
It is convolutional byte interleaver 1302 later.Figure 15 explanation reply influences the interleaver of the impulsive noise of transmission signal
1302 operating mode.Parameter B in path 156,158 is set as 207, and the parameter M in path 152,154,156 and 158
It is set as 1.Frame synchronizing signal 1303 will output and input change-over switch 150,151 and be pushed into top position 1500, thus make to interweave
It is synchronous with frame structure.As byte enters interleaver and different bytes exits interleaver, change-over switch is output and input
150,151 a position 1502 is moved down.When change-over switch 150,151 reaches bottom 1508, they switch back to top
1500.Each of B parallel route 1506,1508 includes shift register 156,158, the shift register 156,158
With length shown in figure 15 (path 1506 with length (B-2) M and path 1508 have length (B-1) M).
Randomizer 1306 by work on the 65,205x 8=521,640 bit of FEC data frame 1324 and by pair
Those of PN (pseudo noise) sequence with length 219-1 bit executes XOR operation to generate the FEC data of randomization
Frame 328 shortens the length of the PN sequence by resetting PN sequencer in each frame synchronization time.
The example of trellis coded modulation (PTCM) module 1308 of optional bit rate perforation is illustrated in greater detail in Figure 16.
PTCM 1308 uses method known to those skilled in the art.This method starts from the encoder of 64 state, 1/2 rate, and holds
Eleven punch 11 is to obtain any one of 5 kinds of different bit rates.In certain embodiments, PTCM 1308 can also be by complete other
Road (bit rate=1).This allows the selectable tradeoff between the net bit rate and white noise acoustic performance of system.Similar trellis coding
Technology is used for ISDB-T and DVB-T system.PTCM generates two ratios at the output of each bit for being supplied to input 1328
Spy 1332.However, some discardings in bit 1332 will be exported according to selected bit rate and respective perforations pattern.QAM reflects
Emitter 1313 fetch the bit in self-encoding encoder output 2,4 or 6 groups of 1332 and by they be respectively mapped to QPSK, 16QAM or
In 64QAM symbol.The example of these mappings is given in Figure 17.
Frame synchronization/mode code element packet (all symbols are QPSK) is added to each FEC data frame 1334 by module 1312
Start.Referring to Figure 18, the first part 180 of the grouping includes 127 symbols and both real and imaginary parts including being directed to symbol
Identical binary system PN sequence.Other PN sequence lengths are also possible, and real and imaginary parts can have opposite symbol.It should
The second part 182 of grouping includes the data of indicating transmission mode, i.e., selected qam constellation and selected trellis code rate.
Block error correcting code can be used to encode for the mode data, for increasing the reliability at receiver.Adoptable method includes that BCH is compiled
Code and other block codes.In one example, 6 kinds of possible trellis code rates comprising bypass are possible.In addition, three constellations can
It can obtain 18 kinds of modes.Therefore, it is necessary to 5 bits to characterize each in possible model selection.This 5 bits can be used
The BCH code of extension is encoded into 16 bit codewords.Since each QPSK symbol includes 2 bits, it is therefore desirable to 8 mode symbols.
Figure 19 explanation is supplied to the frame structure 1336 of passband modulation (PB modulation) 1314 (see Figure 13).Payload 190 wraps
Include 315 RS groupings (521640 bits).The number for the QAM symbol that 315 RS grouping maps to can with model selection and
Variation.PB modulation module 1314 then uses any proper method known to those skilled in the art by base band QAM symbol tune
It makes to passband.
The frame structure of some aspects usefully overcomes certain drawbacks and disadvantages of conventional frame according to the present invention.Specifically
It says, which provides all modes:
The RS of every frame is grouped constant integer, regardless of mode, and
For all modes, the QAM code element number of every frame is variable integer
For all modes, the perforation pattern period of every frame is integer.
Notice assuming that the QAM symbol of the integer of every frame is important realization, because FEC data frame must accurately include
I × 207 data byte, wherein I is selected integer so that every frame is grouped with fixed integer RS.Therefore, it is compiled in lattice
The data bit number of every frame must be not only integer before code, and the data bit number must can be by 207 × 8 for all modes
=1656 divide equally.In addition, the grid encoder output bit number of every QAM symbol is respectively 2,4 and for QPSK, 16QAM and 64QAM
6 bits (are shown in Table 2, table 2 shows bit rate=1 for trellis code bypass).In addition, trellis coding increases bit.Before trellis coding
The data bit number of each code element is illustrated in table 2, wherein each entry is calculated as:
The data bit (the QAM symbol input bit of each mapping to grid encoder) of table 2- each code element
The fact that the data bit number of each code element can be score requires the RS packet size for accurately selecting each frame
With RS grouping number.For the RS packet size of every frame 207 and 315 grouping, every frame integer symbol is obtained.As shown in table 3,
Each entry can calculate are as follows:
The symbol of each frame of table 3-
The frame provides additional advantage, that is, the perforation pattern period (pp/ frame) of frame each for all modes is whole
Number.In order to correctly decode the trellis coding data of perforated, the decoder in receiver must be known by perforation pattern as how about with
Data alignment.It is applied to the secondary series of the table being illustrated in Figure 16 by bit perforation pattern at female code grid encoder output
In.Number 1 in each perforation pattern is perforation pattern length.In the system of proposal, perforation pattern always with FEC data frame
Starting point alignment.This allows in receiver using frame synchronization suitably to make to remove perforator in receiver Viterbi decoder
(de-puncturer) it is aligned with bit stream.Indicated in table 4 require alignment, show for all modes pp/ frame it is whole
It keeps count of.Perforation pattern (pp/ symbol) entry of each code element can calculate are as follows:
Pp/ frame entry can calculate are as follows:
The perforation pattern of the every frame of table 4-
It will be appreciated that other combinations of RS packet size and every frame packet count can be used to obtain identical conjunction and need result.This
In the number that provides be only to explain purpose and describe.
As shown in figure 20, certain embodiments of the present invention provides a receiver, which builds up disposition according to this hair
The frame of bright some aspects construction.The data transmitted in 2000 received passband signal of module simultaneously convert thereof into base band QAM symbol.By
The operation that module 2000 executes may include chip clock synchronous, balanced (remove intersymbol interference) and carrier auxiliary, usually used
Submodule.Therefore, module 2000 may include the balanced device of the recovered base band QAM symbol 2001 of output.Base band QAM signal 2001
Second level sheer 2018 is provided to make cutting to real axis and imaginary axis both direction, is consequently formed and is supplied to frame synchronization module
2020 sequence aR[k] ∈ [- 1 ,+1] and aI[k]∈[-1,+1]2019.QAM symbol of the frame synchronization module 2020 to incoming cutting
2019 execute continuous cross-correlation operation individually for real and imaginary parts with the stored copies of binary frame synchronic PN sequence.Storage
Each member of copy has value -1 or+1.This operation indicates are as follows:
Wherein s is the copy stored in 127 long frame synchronization PN sequence.bROr bIMaximum amplitude indicate FEC data frame
Start.
Once positioning frame synchronization starting position, the position of the code word comprising mode bit (constellation and trellis code rate) just can know that
It sets.It can be for example, by BCH decoder or by the received code word of institute is related to all possible code word and select generation highest
The code word of end value is reliably decoded code word.It, can be by requiring receiving since the information is repeatedly transmitted
Before so that identical result is repeatedly obtained additional reliability.
The frame synchronizing signal 2021 that the export goes out is used to refer to intend before symbol to be fed to soft demapper 2006
Which symbol removed in " removal frame-synchronization/mode symbol " module 2004.In one example, by 127 frame synchronization symbols and
8 mode symbols are removed from stream, to ensure that only symbol corresponding with RS grouping is delivered to soft demapper 2006.It is soft to go to reflect
Emitter 2006 is measured using algorithm known in the art (such as the algorithm described by Akay and Tosato) to calculate soft bit.In order to
Correct work, soft demapper 2006 must be known by using which kind of perforation pattern (which kind of trellis code rate) in transmitter and also want
Know the alignment of the pattern Yu received bit.The information 2021 is provided by frame synchronization module 2020, the frame synchronization module
2020 decoding mode information and simultaneously provide perforation pattern repetition frame synchronizing signal aligned therewith, regardless of present mode why.
These soft bits measurement is fed to Viterbi decoder 2008, which is worked in a manner of known in the art
To obtain the bit estimation for the PTCM encoder being input in transmitter.
Derandomized device 2013, byte deinterleaver 2014 and the RS decoder all synchronized by frame synchronizing signal 2021
It is 2016 derandomized respectively, deinterleaving and decoding byte number obtains the data for initially entering the encoder of the RS in transmitter accordingly.
Carrier phase offset correction
Certain embodiments of the present invention corrects system and method using carrier phase offset.In certain embodiments, it receives
Machine includes: phase offset correction device, which receives the equalizing signal of the characterization as quadrature amplitude modulated (QAM) signal simultaneously
The signal through phasing is obtained from equalizing signal；Second level sheer, the second level sheer cutting equalizing signal is to obtain real number
With imaginary number sequence；Frame synchronizer, the frame synchronizer execute real number and imaginary number sequence and the frame synchronization pseudo-random sequence stored and
The correlation of the corresponding real and imaginary parts of the phase correction signal of phase offset correction device is supplied to by frame synchronizer.Phasing letter
Number based on relevant maximum real number and imaginary value.Frame synchronizer executes continuous intersection phase to incoming cutting quadrature amplitude modulation symbol
It closes.Continuous crosscorrelation is the stored copies with the synchronous PN sequence of binary frame individually for real number and imaginary number sequence
It carries out.
Base band to passband is modulated
Certain radio digital communication systems including broadcast, Wireless LAN and wide area mobile system use with some form
QAM.QAM is also used for North America and European digital cable television standard using quadrature-carrier multiplexing, and quadrature carrier multichannel is multiple
Identical channel width is occupied with the carrier modulation wave for allowing two double sidebands to inhibit, each wave is modulated by independent message.Such as
Upper described, Figure 23 describes the simple QAM modulation device that may act as the modulation of the PB in Figure 13 example 1314.The QAM pulse of isolated transmission
It is expressed as follows:
Wherein dR,mAnd dI,mIt is the real and imaginary parts for being determined by two independent message streams and being respectively indicated multiple QAM symbol
(see such as Figure 17), wherein qam constellations are tieed up in the 2 of m=1 ... M index radix, and wherein M is modulated carrier frequencies, and q (t) is root
Raised cosine pulse function.
The transmission QAM pulse s (t) of one continuous series is with rate Fs=1/TsIt is transmitted by the multi-path channel with noise.Cause
This, the reception signal in the input of QAM receiver is expressed as r (t)=s (t) * c (t)+v (t), and wherein * indicates convolution, c (t)
It is channel impulse response, and v (t) is additive white Gaussian noise.Therefore:
Wherein d [n] is multiple transmitted symbol, foAnd θoRespectively relative to the receiver pass-band of transmitter to base band demodulator
The frequency shift (FS) and phase offset of local oscillator, thus fLO=fc-fo。
Passband is to base band demodulator
Figure 35 illustrate in greater detail PB to BB in Figure 20, chip clock it is synchronous, balanced device/carrier recovery block 2000 one
A example.Rate of the received signal r (t) to be higher than chip rate generates sampled signal r by sampling 350
(nTsamp).After sampling:
Then, after demodulation, with chip rate 1/TsIt samples again and matched filtering obtains:
Wherein v ' [k] is sampled multiple filter noise.This assumes due to pulse shaping and matched filtering q and perfect symbol
Polydispersity index timing is combined, and any ISI is attributable simply to channel impulse response c.After demodulation, it is assumed that perfect equilibrium, then balanced device
Nearly base band complex sequences z [k] at output indicates are as follows:
Therefore, recovered nearly baseband sequence represents the constellation sent, has with frequency foThe phase offset θ of rotationo。
In order to reliably restore transmitted dRAnd dI, for example two-dimentional sheer of use, balanced device and phase and frequency offset restore loop
Combination must eliminate the frequency shift (FS) f for causing constellation rotationo, this and receiver must eliminate θoRemaining static phase offset,
Otherwise constellation will be made for the position of static state rotation.
In order to understand that phase/frequency is restored, it must be understood that the qam constellation at base band.In the simple examples of Figure 33 A,
4QAM for being also referred to as QPSK is modulated, and constellation is made of four symbols.In discribed example, the real and imaginary parts of d [k]
2 different values (such as ± 3) can respectively be asked for.Phase offset θoFigure 33 B is illustrated in the effect of the d [k] of recovery, Figure 33 B shows
Rotation in complex plane out.Notice that rotation carries out in a circle at any time, according to foSymbol either counterclockwise or
It rotates clockwise, can thus understand foEffect.
Balanced device and carrier phase/frequency ring
In Figure 34, signal x [k] 340 is by digital equalizer and carrier phase/frequency ring 248 (for example, see Figure 24 A)
It is received.The component of balanced device 341 generally includes linear digital filter, and uses such as lowest mean square (LMS) algorithm
Privately owned or known method, balanced device 341 outputs it y [k] and sheer is adjudicated343 phase-rotated edition comparisons with
Error signal is formed, which is used to calculate the update collection of filter tap weights.The filter is removed by channel pulse
Respond ISI caused by c.
The independently real and imaginary parts of cutting z [k] and the output of 2-D sheer 342 It is the d [k] of original transmitted
Estimation.Z [k] andThe two enters phase error detector module 346 and forms phase error signal, phase error letter
It number is expressed asIntegral ratio (IP) filter 345 may include Figure 35 filter or skill in the art
Any equivalent known to art personnel.IP filter 345 allows both the offset of loop phase calibration and frequency shift (FS).IP filter
345 output is fed to multiple voltage controlled oscillator (VCO) 344, which exports for correcting θoAnd foThe two is answered
Phase/frequency correction factor e-jθ[k].VCO 344 also exports (e+jθ[k]) with " not correcting " cutting outputSo that it is available
To obtain the error signal updated for equalizer tap.This method is shown, because balanced device work is including θoAnd foThe two
On x [k].
It in certain embodiments, can be by the way that VCO 344 be embodied as to feed a complex exponential look-up table (LUT) with absolute version
The delay of integrator obtain effect.However, can have the ambiguity of pi/2 to the correction of a final proof of θ o, ambiguity meaning
Taste recovered phase may be correctly (offset=0) or can have the offset of pi/2, the offset of π or the offset of 3 π/4.This
A little results are illustrated in Figure 36 and Figure 37, and: Figure 36 shows the symbol actually sent, and Figure 37 A-37D show with each offset can
The recovery symbol of energy.Typically, receiver can not know in these four possible symbols it is any be actually being sent because 2D is cut
Device 342 is divided to execute nearest adjacent operation.Figure 38 shows the symbol α wherein sent and is received as the reality of α ' in balanced device input
Example, as shown, having angle theta between α and α 'o.Therefore, phase recovery loop can make signal rotation to compensate θo, so that a ' with
A alignment.However, it is b that the judgement of 2D sheer 162, which will be correction symbol, because it is closer to α '.It is extensive that this may cause phase
Multiple loop by rotated constellation by make a ' in alignment with b in a manner of restrain.In this case, final phase from its should position
Offset-pi/2.
Certain embodiments of the present invention provides the method for minimizing and/or eliminating these problems in trellis coding system, packet
Include the analog for trellis code of perforating used in certain presently described embodiments.As described above, the output of balanced device passes through 2D
Grade sheer 342 is split along both real axis and imaginary axis direction with formation sequence aR[k] ∈ [- 1 ,+1] and aI[k] ∈ [- 1 ,+1],
The sequence is fed to frame synchronization module 2020 (see Figure 20).Frame synchronization module 2020 is deposited using binary frame synchronic PN sequence
Copy is stored up incoming through executing continuous cross-correlation operation to both real and imaginary parts respectively in cutting QAM symbol.Storage
Each member of copy has value -1 or+1.This operation is characterized as:
Wherein s is the stored copies in 127 long frame synchronization PN sequence.bROr bIMaximum amplitude indicate FEC data frame
Start.
Table 5
For frame synchronization symbol, real and imaginary parts symbol having the same and its constellation is illustrated in Figure 39.It therefore, can be with
Understand, maximum amplitude bROr bISymbol to zero rotation for be positive.The rotation of pi/2 generates negative maximum amplitude bRWith it is positive
Maximum amplitude bI.Rotation for π, bRAnd bIIt is negative, the rotation for pi/2, maximum amplitude bRIt is positive and maximum amplitude bIFor
It is negative.This has summarized in the above table 5.Therefore, maximum amplitude bRAnd bIEach symbol indicate that final phase offset has restrained together
Which quadrant into complex plane.Additional phase correction is applied to signal like that as illustrated in fig. 20 by this permission.Maximum bRAnd bI
Symbol from being sent to phase offset correction device based on relevant frame synchronization module.The behaviour of one phase offset correction device module
It is illustrated in Figure 40, wherein showing LUT operation 404 in one example.Assuming that z [k]=zR[k]+jzI[k], the operation can letters
Singly execute are as follows:
In the case of φ=+ θ: z ' [k]=- zR[k]-jzI[k]
In the case of φ=+ pi/2: z ' [k]=- zI[k]+jzR[k]
In the case of φ=- pi/2: z ' [k]=+ zI[k]-jzR[k]
Figure 40 is that some aspects by indexing there is the symbol of maximum real number and imaginary number correlation to look into according to the present invention
Table is looked for obtain the block diagram of the phase offset correction device through phase correction signal.
The detection of multimode qam constellation
Some embodiments provide for from one group it is possible receive qam constellation in determine a unknown qam constellation system and
Method.A kind of method is after using modified constant modulus algorithm (CMA) balanced device to minimize intersymbol interference (ISI) but is carrying
Wave frequency rate and phase utilize the distribution map of signal power before restoring completely.Then unknown constellation is determined from the distribution map.
It is then based on nowadays known constellation and with standard CMA starts again at balancing procedure so that ISI is minimized.Equilibrium can correctly be scaled
Device output, the constellation carrier auxiliary (RCCR) simplified and decision-directed carrier auxiliary stage can be performed after this, thus lead
Cause the recovery by combined balanced device carrier frequency/phase loop carrier frequency and phase.For determining unknown QAM star
In the another method of seat, balanced device is worked at the beginning using the CMA being corrected to minimize ISI.Although balanced device is exported at this
This time point of process may not be scaled correctly, however RCCR can be used to restore in balanced device carrier frequency/phase loop
Why carrier frequency and phase are without knowing constellation.The phase of recovery may be with noise.Receiver, which can be read, to be embedded into
Which qam constellation information in signal frame, information instruction are transmitting.Known constellation is then based on to be opened again with standard CMA
Beginning equalizer operation is RCCR and decision-directed carrier auxiliary later.
Certain embodiments of the present invention, which uses, to be similar to used in ISDB-T and those of aforementioned perforation trellis coding and QAM
Constellation combination.As used herein, constellation is understood to mean reflecting in the complex plane in possible symbol in modulation scheme
It penetrates.The code element number of each frame is the variable integer depending on mode, and the RS packet count of each frame is constant integer, not pipe die
Why is formula.It is this to configure the design for being described in more detail and having simplified receiver in front.
Referring again to Figure 20, frame synchronization module 2020 is cut using the stored copies of binary frame synchronic PN sequence in incoming
Divide in QAM symbol 1219 and continuous cross-correlation operation is executed to real and imaginary parts respectively.Each member of stored copies has
Value -1 or+1.It is repeated herein by this operation that equation 10 (above) provides:
Wherein s is the stored copies in 127 long frame synchronization PN sequence.bROr bIMaximum amplitude indicate FEC data frame
Start.
As described in greater detail below, there are the ambiguities of pi/2 in exalted carrier phase.This cause 0, ± π/
Any additional recovery phase offset of 2 or π.For frame synchronization symbol, real and imaginary parts symbol having the same, therefore to it
For transmitted constellation it is as shown in figure 39.Therefore, it will be appreciated that, maximum amplitude bROr bISymbol to zero phase offset for
It is positive.As the table 404 of Figure 40 is summarized, the offset of-pi/2 will generate negative maximum amplitude bRWith positive maximum amplitude bI；
Offset for π, bRAnd bIBoth it is negative, and the offset for pi/2, maximum amplitude bRIt will be positive and maximum amplitude bITo be
It is negative.Therefore, maximum amplitude bRAnd bIEach symbol indicate together final phase offset converged to which of complex plane as
Limit.This allows for additional phasing to be applied to the signal of phase offset correction device module 2002.Maximum bRAnd bISymbol can
Phase offset correction device 2002 is sent to from based on relevant frame synchronization module 2020.
See also Figure 40, the operation of some aspects of the phase offset correction device 2002 in Figure 20 example can be obtained more
Good understanding.LUT 400, which is generated, is based on maximum amplitude bRAnd bISymbol output (see the element 404 in Figure 40).Assuming that z [k]
=zR[k]+jzI[k], operation 402 execute as follows:
1) for φ=+ π situation: z ' [k]=- zR[k]-jzI[k]
2) forSituation: z ' [k]=- zI[k]+jzR[k]
3) forSituation: z ' [k]=+ zI[k]-jzR[k]
Once positioning frame synchronization starting position and the phase offset for correcting m pi/2, just can know that comprising mode bit
The position of the code word of (constellation and trellis code rate).It can be for example, by Bose-Chaudhuri-Hocquenghem Code device or by by the received code word of institute and all possibility
Code word it is related and select the code word for generating highest end value reliably to be decoded to code word.Since the information is repeated hair
It send, therefore can be by requiring that identical result is made repeatedly to obtain additional reliability before receiving.
Figure 41 shows the example that the process can be executed by frame synchronization module 2020.In response to frame synchronizing signal 2021,
In step 4100, the received constellation code word of institute and all effective code word crosscorrelations.Crosscorrelation generation can be used to select most may be used
It can matched value.In one example, effective code word of generation maximum related value is selected in step 4102.The code word of the selection is then
It can be used to identify current constellation.In step 4104, what the identity of current constellation was stored with record or in other ways knows before
The identity of other constellation is made comparisons.If current constellation and the constellation identified before are same constellations, then confidence meter in step 4104
Number device is incremented by.If the constellation that identifies is different from current constellation before step 4104 determines, in step 4107 by current star
Seat is recorded as the constellation identified before and confidence counter successively decreases in step 4017, and waits another synchronization in step 4109
Frame.After confidence counter is incremented by by step 4106, confidence counter is checked in step 4108, if set in step 4108 determination
Letter counter has exceeded predetermined or configuration threshold value, then the judgement of signal constellation (in digital modulation) is made in step 4110.The process can be performed
Iteration is until confidence counter is beyond predetermined or configuration threshold value.
Balanced device and carrier phase/frequency ring
Referring to fig. 42, the balanced device of Figure 24 A and some aspects of carrier phase/frequency loop 248 will be described.Signal x [k]
Into digital equalizer and carrier phase/frequency loop 248, the digital equalizer and carrier phase/frequency loop 248 may include
Balanced device 420 with linear digital filter.422 error signal e [k] of error calculator module, the error signal e
Any proper method well known by persons skilled in the art can be used to calculate the update collection of filter tap weights in [k].At one
In example, LMS algorithm can be used.Filter removes the ISI as caused by channel impulse response c.The output y [k] of balanced device 420 with
Make phase rotation 421 afterwards to reduce any remaining carrier phase and frequency shift (FS).Phase-rotated output z [k] then by
Sheer and phase error detector module 427 are handled, and the calculating of phase error detector module 427 is fed to integral ratio
(IP) the phase error e of filter 426θ[k].The output of IP filter 426 is fed to integrator and complex exponential look-up table
(LUT) 424, it is inclined to correct carrier phase and frequency which calculates complex exponential value used in loop
It moves.Sheer and phase error detector module 427 also export the two-dimentional sliced symbols judgement of nearest neighbor, and phase is 425
By with e+jθ[k]It is multiplied and " not being corrected " and will then be used for error calculator module 422.Error calculator module 422
Using the input and x [k] come error signal e [k].As depicted, error calculator module 422 and sheer and
The inside operation of phase error detector module 427 depends on the current generation (1,2 or 3) of operation, these stages are by the stage
What controller 423 determined.
In certain embodiments, equalizer filter tap weight is calculated using lowest mean square (LMS) algorithm and make as follows
Operation:
X [k] is enabled to indicate that the balanced device input vector of L length, y [k] indicate balanced device output vector, wherein y [k]=gH
[k] x [k], wherein gH[k] is the linear equalizer tap-weights vector of L length and H subscript indicates that conjugation exchanges that (Hermit is total
Yoke).Then, use example method as described below come calculate in error calculator module 422 be updated e [k]:
G [k+1]=g [k] -2 μ x [k] e*[k], (equation 11)
Wherein μ is small step parameter and subscript * indicates complex conjugate.
In this example, phase controller 423 obtains balanced device and carrier phase/frequency loop by three stages operatings
428, take this to sample the simple count threshold value of x [k] based on input data to execute the switching from stage 1 to stage 2 to the stage 3.
Note that the switching of more complicated stage of the error estimation based on balanced device outlet side is also possible.These three stages are general in table 6
It includes.
Table 6: balanced device and carrier phase/frequency loop stage
Sheer and phase error detector module 427 are illustrated in greater detail in Figure 43.According to the three phases 434 of operation
In a configuration switch 430.During the stage 1, switch 430 is in extreme higher position, therefore eθ[k]=0.This is effectively disconnected from
Carrier loop, thus at this stage during without any carrier phase correction.During the stage 2, switch 430 is in interposition
It sets and loop is worked using simplification constellation carrier auxiliary (RCCR) algorithm.If with | z [k]2The power of the symbol z [k] of expression
Beyond threshold xi, then assume that z [k] is one in the corner symbol of constellation and RCCR is the second switch 432 by that will describe
It is set in high-order and enables, obtain eθ[k]=Im { z [k] α [sign (z*[k])]}.Otherwise, if | z [k] |2≤ ξ, then
Two switches 432 are in the low level for the disabling carrier loop described.Therefore, only one subset can be during the stage 2 in symbol
There is benifit to carrier auxiliary.Threshold xi can be reduced so as to include high more multiple-symbol in the region of constellation near corners, but resulting
Phase correction terms eθ[k] will have more noises.During the stage 3, switch 430 is in the extreme lower position described, and obtainsWhereinIt is 2 dimension sliced symbols judgements of nearest neighborComplex conjugate.In 3 phase of stage
Between, it is assumed that time enough is had been subjected to so that equalizer tap has been restrained and carrier phase basic correction, thus through cutting
Bit decision be reliable.In particular, relational expressionWithEffectively
Ground works in the single quadrant of complex plane.This leads to the ambiguity of the m pi/2 in exalted carrier phase as described above.
The example of IP filter 426 (see Figure 42) is illustrated in greater detail in Figure 35.IP filter 426 allows loop to correct phase
Both position and frequency shift (FS).The output of IP filter 426 is fed to integrator and complex exponential LUT module 424, and Figure 45 is more detailed
Carefully show.The input of integrator/LUT 424 adds 440 (Figure 44) to a step 442 versions of delay of input by 2 π moulds, to be formed
Phase error signal θ [k], phase error signal θ [k] are fed to look-up table (LUT) 444,444 output phase of look-up table
Correction factor 445e-jθ[k], it is used to correct θoAnd foThe two.LUT 444 also provides output 446 (e+jθ[k]), output " the not school
Just " sheer exportsSo that it can be used for exporting the error signal updated for equalizer tap.This method is necessary
, because balanced device work is including θoAnd foOn the x [k] of the two.
Error calculator module and stage operation are summarized
Error Calculator 422 can employ different approach to calculate e [k] according to the stage.For stage 1 and stage 2, e [k]
It is calculated to usually use the process based on constant modulus algorithm (CMA):
E [k]=y [k] (| y [k] |2-R),
Wherein R is scheduled constant, is indicated are as follows:
Wherein E is expectation operator and d [k] is symbol (see Figure 17).Pay attention to the e that the tap for triggering above equation 11 updates
[k] is independently of the phase of bit decision and x [k], and only relies upon balanced device output, balanced device input and constellation
Statistics.As can be seen that triggering equation 11 using CDMA error and being equivalent to minimizes ISI, i.e., during stage 1 and stage 2
Rotate constellation due to carrier frequency and phase offset.
Therefore, during the stage 1, it is disabling that phase/frequency, which restores loop, and balanced device uses CMA error function
Minimize ISI.After minimizing ISI, the stage 2 starts and RCCR is connected in loop；Carrier phase/frequency is restored
Start using only the corner symbol of constellation, as above in conjunction with Figure 43 explanation.At the end of stage 2, carrier phase and
Frequency has been thus capable of sufficiently recovering so that the 2 dimension sheers 436 of Figure 43 start to export reliable bit decision
Decision-directed (DD) error can use in the stage 3.DD error can be calculated asFor
Illustration purpose, it is assumed herein that receiver has determined that just sending is which of three constellations of Figure 17, because for this
Each of a little constellations, R is different.In addition, RCCR requires to know constellation, the function of the corner symbol of constellation is especially known
Rate.
CMA with unknown constellation
In example described herein, one in transmittable three different Q AM constellations, and above-mentioned balanced and phase/
Frequency retrieval needs to know transmitted constellation.Although constellation selection encodes in mode symbol, balanced and phase/frequency
Frame synchronization (see Figure 20) is led in recovery, and the information is directly decoded as described above (for example, see Figure 18, Figure 20 and figure at this time
41).As a result, in certain embodiments, constellation is determined in balanced device and carrier recovery algorithm itself.
Notice that R (as provided in equation 12) is that constellation is interdependent.In certain embodiments and with continued reference to Figure 17,64-
The real and imaginary parts of the symbol of QAM are selected from collection ± { 1,3,5,7 }, and the real and imaginary parts of the symbol of 16-QAM are from collection
It is selected in ± { 2,6 }, and the real and imaginary parts of QPSK symbol are selected from collection ± 4.According to equation 12, the value of R be will is that
For any one of three constellations of Figure 17, it can be seen that made using the scaled value α R of CMA error calculation
Equalizer filter tap converge to byThe same class value of scaling, wherein balanced device output are equally scaled.As can be seen that
ISI is still minimized.In a unknown example of constellation, R may be set to 58 but regardless of transmitted constellation why, ISI
It is minimized during the stage 1.For the example, any value R in range 32-58 can be used.However, maximum value (i.e. 58)
Selection prevent equalizer output most dense constellation (being 64-QAM herein) compress and alleviate equalizer performance
Burden.
By the upward scaling of the balanced output of convergent filter tap, therefore the use of scaled CMA parameter R causes
The statistical value of balanced device output will be:
E{|y[k]|4}/E{|y[k]|2}=58,
Assuming that perfection eliminate ISI and regardless of constellation why.Therefore, for QPSK, during the stage 1, balanced device is defeated
Scaling will be proceed as follows after ISI has been minimized out:
Figure 45 A is explained in θ0=f0The real part of the balanced output of the system of QPSK is used in the case of=0.It can be seen that because
For value R=58, when equalizer convergence to the solution for eliminating ISI, output byScaling.Figure 45 B is explained in θ0=f0=0
The real part of the balanced output of the system of 16-QAM is used under situation.Due toRelatively closer to 1, therefore balanced device exports
Real part seem and be only slightly scaled.Therefore, during equalizer convergence, practical scaling is apparent.
Constellation detection method
In certain embodiments, constellation can be determined using profiling method before entering the stage 2.Even if carrier phase and
Frequency is not yet resumed, and also can determine that constellation.Consider balanced device output power η [k]=y [k] y*The distribution map of [k], Figure 46 A,
QPSK constellation, 16-QAM constellation and 64-QAM constellation is shown respectively in 46B and 46C.The expression of these distribution maps has been restrained in balanced device
Power afterwards, wherein R=58.Since the power of balanced device output is substantially not independently of the distribution map of phase and each constellation
With, therefore can the constellation sent be determined from balanced device output power distribution map in receivers.
If not having additivity or tap noise, for QPSK constellation, the power of each balanced device output sampling is η
[k]=58.For 16-QAM constellation, the probability mass function of the power of balanced device output are as follows:
Equally, for 64-QAM constellation, the probability mass function of balanced device output power are as follows:
Since the tap in input signal updates noise and additive noise v ', even if the substantive SNR to such as 30dB comes
Say also there is certain extension in the distribution map of these values.The noise modeling that balanced device is exported be additivity and independently of
Symbol, and assume to export no ISI, then
|y[k]|2=| d [k]+n [k] |2=| d [k]+n [k] |2=| d [k] |2+|n[k]|2+2Re{d[k]n*[k]}
(equation 16)
Variance --- itself and 2Re { d [k] n adjusted in given symbol*[k] } item association --- as symbol power increases
Add and increases.In distribution map, which is expressed as the extension around given constellation power, i.e. variance, it is with symbol function
Rate increases and increases.Under 16-QAM situation, around symbol ± 2.1 ± j2.1 constellation power extension be less than around symbol ±
The extension of the constellation power of 6.3 ± j6.3.
Certain other relationships can be observed from the distribution map of balanced device output power:
Region T in QPSK distribution map1Substantially respectively fall in second and third region R of 16-QAM distribution map2And R3It
Between.Therefore, the region which kind of symbol power declaration transmits is nonoverlapping for QPSK and 16-QAM constellation.
The comparison of QPSK distribution map to 64-QAM distribution map is disclosed for 64-QAM'sTherefore, for η [k] and region T1Comparison, more likely η [k] fall in the region it
Outside.
There is no in the example of noise in 64-QAM, η [k] is taken from collection { 2,18,26,34,58,98 } with probability 9/16
Value.Therefore, when potential constellation is 64-QAM, ignore noise:
Pr{(η[k]∈R1)∪(η[k]∈R2)∪(η[k]∈R3) < 1/2, (equation 17)
Wherein ∪ indicate OR (or).Therefore, if transmitted constellation is 64-QAM and by η [k] and region R1、R2And R3
Compare, then η [k], which is very likely to, falls in except these regions.
Some embodiments use the algorithm based on these observations:
K=0, λ4[- 1]=0, λ16[- 1]=0
while k≤N do
η [k]=y [k] y*[k]；
If η[k]∈T1then
λ4[k]=λ4[k-1]+1；
else
λ4[k]=max { λ4[k-1] -1,0 }；
end if
If((η[k]∈R1)∪(η[k]∈R2)∪(η[k]∈R3))then
λ16[k]=λ16[k-1]+1；
else
λ16[k]=max { λ16[k-l] -1,0 }；
end if
K=k+1；
end while
The algorithm can start after balanced device has been restrained, and if balanced device output power is in region T1It is interior, then
Make QPSK counter λ in the output sampling of N number of balanced device in first part4[k] is incremented by.If balanced device output power is not at
Region T1It is interior, then counter is successively decreased.Equally, if η [k] falls in region R1、R2And R3It is interior, make 16-QAM counter λ16[k] is passed
Increase, otherwise just it is made to successively decrease.
After the output sampling of N balanced device, it will be assumed that distribution map is special by correct earth's surface.If potential constellation is 64-QAM,
It will be fallen in outside the region QPSK and 16-QAM due to being more likely to power estimation η [k], QPSK and 16-QAM counter will be suitable
It is small.If transmitted constellation is QPSK or 16-QAM, the counter for sending constellation will be significantly bigger.Therefore,
If(λ4[N] < M) ∩ (λ16[N] < M) then
64-QAM Constellation Transmitted.
else
If λ4[N] > λ16[N]
QPSK Constellation Transmitted.
else
16-QAM Constellation Transmitted.
end if
end if
Threshold value M can be empirically determined, but it should be smaller relative to N.The algorithm be it is extremely strong, when transmission QPSK,
When 16-QAM or 64-QAM, correction constellation is reliably selected for low signal-to-noise ratio (SNR).It, can after having reliably determined constellation
R is set as correct 13 value of equation and the stage 1 can tend to finish.Balanced device output will be by the properly scaling and stage 2
It can be since knowing threshold xi required by RCCR.
Another method that constellation is determined before balanced device enters the stage 3 will now be described.In the method, the stage is executed
1 and allow to finish in R=58.Therefore, as described, all three constellations are scaled in equalizer output, this is obtained
The y [k] as shown in three constellations of Figure 47, although these constellations may be rotation.As in conjunction with Figure 43 description as, rank
Section 2 it is critical that RCCR is with | z [k] |2The power of the symbol z [k] of expression exceeds the symbol in the case of threshold xi
Uniquely consider.Then it may be assumed that z [k] is one in the corner symbol of constellation.Equally,It can indicate corner code
Member.As Figure 48 (A) is explained for 64-QAM constellation, the value of ξ is selected to be relatively easy to when known to constellation.Figure 48 shows
Restore all three constellations of loop module input in balanced device output and carrier phase/frequency out.As can be seen that for this
A little corners point | z [k] |=9.90.For example, the threshold value indicated by circle of dotted line 484Ensure only to select corner point.Equally,482 Hes of circleCircle 480 can be used together with 16-QAM with the abundant allowance of QPSK respectively.
Figure 49 shows the coverage diagram of the right upper quadrant of all three constellations.If can be seen thatThen only fall in
The corner point of QPSK and 16-QAM except circle of dotted line can be utilized by RCCR.However, if receiving 64-QAM, five constellation points
(four non-corners) falls in except circle and will be utilized by RCCR.Since the phase of recovery has less noise, RCCR generally makes
Behaved oneself best in the case where the constellation point of corner.However, even if using some annex points, although will lead to the increasing of phase noise
Add, RCCR also will successfully restore phase.Therefore, the stage 2 can work at the beginningThis allows in constellation to reception
The abundant initial carrier auxiliary of all three constellations while machine keeps unknown.
As above in conjunction with Figure 20 description, balanced device 2000 is fed to 2 grades of sheers 2018, and 2 grades of sheers
2018 then successively feed to frame synchronization 2020.Frame synchronization 2020 can be used the storage version of binary frame synchronic PN sequence to incoming
The QAM symbol through cutting the continuous cross-correlation operation of semiology analysis, as described in equation 10.Continuous crosscorrelation
Operation can independently execute real and imaginary parts.Each member of storage version has -1 or+1 value.bRAnd bIMaximum amplitude
Indicate the beginning of FEC data frame.Nowadays the only difference is that, for 64-QAM constellation, 2 grades of work of sheer 2018 have certain
On the signal of one additional phase noise.However, the additional phase noise is to 2 grades of cuttings and next based on the frame of crosscorrelation
It is synchronous that there is very small negative effect, even if it is also very strong there are phase noise.As previously mentioned,
The decoding of constellation code word is also very strong for phase noise.
Figure 50 explanation is used to determine the operation of this possible alternative of constellation, which can be summarized as follows:
(1) balanced device and phase/frequency loop make the stage 1 finish in R=58, subsequently into the stage 2.
(2) different from loitering phase 3, it is to receive input data during the stage 2 based on relevant frame synchronization 2020, seeks
Frame synchronization is looked for, and constellation code word is decoded.
(3) determining constellation information 2021 is sent back into balanced device 2000 and phase/frequency loop, the phase/frequency loops
Road returns to the stage 1 using R value, which suitably corresponds to fixed constellation.
(4) then ending phase 1,2 and 3 as before.
It will be appreciated that the initial differences between the system that Figure 50 and Figure 20 describes are from frame synchronization 2020 to carrying constellation information
Balanced device/carrier auxiliary 2000 additional connection 5000.
SPOT monitoring in coaxial cable safety chain
Certain embodiments of the present invention improves the performance of system and device including those aforementioned systems, and wherein base band regards
Frequency signal can be combined with the digital representation of baseband video signal and with control signal, thus be allowed (" same in such as coaxial cable
Axis ") unit cable on transmitted.Referring again to Fig. 4, one embodiment of the present of invention provides safety chain on coaxial cable
(SLOC) system.Fig. 5 shows a kind of possible modulation scheme of SLOC system.In this example, HD video camera 30, which provides, includes
The IP output 41 for being compressed digital HD video image and the auxiliary camera signal comprising simulating SD CVBS 330.Through compressing
HD video IP signal 332 be modulated to passband 52 using SLOC camera side modem 49, the modulation of SLOC camera side
Demodulator 49 includes QAM modulation device (see the modulator 212 in the modem 32 of Figure 21).The offer of modulator 212 can be with base
With the combined modulated signal of simulation CVBS signal 330." downstream " transmission is usual on coaxial cable 41 for combined signal
It may extend to 300 meters or longer distance.In monitor side, SLOC monitor side modem 45 is by base-band CVBS signal
330 separate with passband downstream IP signal 332.Isolated CVBS signal 330 is fed to SD display 43 for real-time, no-delay
Viewing.Passband downstream IP signal 332 is demodulated with qam demodulator (see the demodulator 222 in Figure 22), which will
Signal is exported to mainframe network interchanger 44 or processor/DVR (being not shown in Fig. 4).
In this embodiment, upstream communication is provided according to IP agreement demand.Can extraly using upstream communication 334 with by audio and
Camera control signal is sent from monitor side to video camera 40.Usually, the bit rate of stream signal --- and therefore wanted
The bandwidth asked --- far below bit rate required by the passband signal of downstream and bandwidth.Monitor side SLOC modem 45 wraps
It includes QAM modulation device (see the modulator 224 in Figure 22), the QAM modulation device is by IP signal modulation to upstream passband 44.Such as Fig. 5 institute
Describe, upstream passband 54 and downstream passband 52 are located at different spectrum positions.In camera side, SLOC modem 49 includes
For receiving the qam demodulator of stream signal (see the demodulator 214 in the modem of Figure 21).The method is provided better than existing
Have several advantages of system and method, including increased working range, existing coaxial cable infrastructure deployment easy to use with
And obtain low delay, real-time video.The rough schematic view of Figure 21 and Figure 22 shows the SLOC camera side modem of Fig. 4
The further details of the SLOC monitor side modem 45 of 49 and Fig. 4, and be described in detail above.
Figure 51 A shows the SLOC system based on Fig. 4 institute interpretation system, wherein the tap 519 through filtering is arranged on coaxially
So that tap 513 and 512,514 effect of cable segmentation are to be connected to prison for camera side equipment between cable segmentation 512 and 514
Visual organ sidepiece part.Tap 513 through filtering is commonly used in extracting at least part of base-band CVBS signal 5100 to video camera
Side SD display 5130.Display 5130 may be provided at video camera 510 nearby for test, configuration and/or part monitoring.Through filtering
The tap 513 of wave generally includes low-pass filter, the low-pass filter stop may interfere with display function 5130 such as through adjusting
Number, IP and/or the undesired signal for controlling signal of system.Tap 513, which may also comprise, stops modem 511 and 515
Between signal transmission filter or switch.For example, test modem can be 5131, it can be connected by tap 513
The trouble shoot or initial configuration to realize camera side modem 511 are connect, and display side modem 515 can
It is disconnected the interference and/or deterioration to avoid signal.As shown in figure 5, SLOC camera side modem 511 usually removes
Also video camera of the output based on the signal 5102 lower passband QAM signal that generates part outside base-band CVBS signal 5100, and SLOC
Upper passband QAM signal of the output of monitor side modem 515 based on the control signal in signal 5170.Tap can be passed through
513 provide one or more filters to avoid on SD display 5130 and/or 516 it is visible do not conform to need to interfere and stop IP
With control signal.Stop the higher frequency signals in passband signal (relative to base band it will be appreciated that some displays and monitor lack
VCBS signal 5100) necessary to filtering.
Figure 51 B shows the SLOC system based on Fig. 3 institute interpretation system, wherein the electricity between camera side and monitor side
Cable 514 is temporarily disconnected in camera side, and SD shows that equipment or display 5130 are directly connected in cable segmentation 519
In SLOC camera side modem 511.Test modem 5131 is optionally connected for testing/configuration purpose.
SD shows that equipment 5130 shows base-band CVBS signal and provides the view near video camera physical location of the monitoring from video camera 510
Frequently, and it may require reconstructing these connections in favor of configuration and trouble shoot.In Figure 51 B, lower passband QAM signal 5102 can
It can cause not conforming to the visual interference needed on the SD display 5130 for lacking High frequency filter.
In the example shown in Figure 51 A and 51B, may occur between modem 511 and 515 signal part or
It is all off.The part of signal, which disconnects, can make QAM signal transmission path keep complete.However, some reconstruct of connection cause to take the photograph
The disconnection of QAM signaling between camera side modem 511 and monitor side SLOC modem 515.Of the invention is certain
Embodiment provide make camera side modem 511 stop passband QAM transmission mechanism, when modem 511 and 515 it
Between connection disconnect when, only export CVBS signal.It will be appreciated that with test modem 5131 to display side modem
It is interim substitution generally include it is a series of, comprising: in the separated of modem 511 and 515, establish modem 511
And the connection between 5131, modem 511 and 5131 it is separated lay equal stress on newly establish modem 511 and 515 it
Between connection.The various functional components of modem 511 can be used to detect the disconnection of QAM signal.Therefore, SLOC system
Operation is described in detail as follows.
The QAM modulation device framework of SLOC system
As described above, Figure 19 explanation is supplied to the frame structure 1336 of passband modulation (PB modulation) module 1314 (see Figure 13).
The trellis coding of Figure 16 increases bit；The data bit number of the QAM symbol of each mapping is before trellis coding (as shown in table 2).
The number for the QAM symbol that the 315RS grouping (521640 bit) of Figure 14 maps to changes with model selection.For every frame
The RS packet size of 207 and 315 groupings obtains whole every frame integer symbol, as shown in table 3.PB modulation module 1314 is subsequent
Base band QAM symbol is modulated to passband (see, for example, the above knot using any proper method known to those skilled in the art
Close the explanation of Figure 24).
As described above, the qam demodulator of Figure 21 and Figure 22 are described further in conjunction with Figure 20.Module 2000 receives
The data transmitted in passband signal simultaneously convert thereof into base band QAM symbol.Symbol is generally included by the operation that module 2000 executes
Clock synchronization, balanced (remove intersymbol interference) and carrier auxiliary, leading to is using submodule.Correspondingly, module 2000 may include
Export the balanced device of recovered base band QAM symbol 2001.Base band QAM signal 2001 be provided to second level sheer 2018 with
Cutting is made in real axis and imaginary axis direction, and the sequence a for being provided to frame synchronization module 2020 is consequently formedR[k] ∈ [- 1 ,+1] and aI[k]
∈[-1,+1]2019。
Frame synchronization module 2020 passes through cutting QAM symbol 2019 of the stored copies in stacking of binary frame synchronic PN sequence
It is upper that continuous cross-correlation operation is executed to real and imaginary parts respectively.Each member of stored copies has value -1 or+1.Pass through
This operation that equation 10 provides repeats herein:
And
Wherein s is the stored copies in 127 long frame synchronization PN sequence.bROr bIMaximum amplitude indicate FEC data frame
Start.When detecting FEC data frame initial point in a stream, in frame-synchronizing impulse or other synchronization signals and receiver module
One or more communications.
Figure 52 A and 52B show the processes element that frame-synchronizing impulse can be reliably generated when receiving with noise signal.Figure
52A shows a part of the process of determining frame length.Frame length can change according to selected transmission mode (table 3).Start from walking
Rapid 5200 process is repeatedly executed with symbol reception, and symbol counter keeps tracking to cause to be higher by predetermined threshold
Code element number between each execution of value.In step 5201, crosscorrelation, and cell count are executed to the symbol reached every time
Device is incremented by, until until step 5202 determines and exceeded predetermined threshold.Symbol counter is incremented by 5203 to each code element, until
Until the threshold value.When step 5202 exceeds the threshold value, then symbol counter is reset 5204 and execute crosscorrelation
Step 5205, symbol counter is incremented by 5207, new symbol 5208 is received in multiple connection of laying equal stress on, and has been exceeded until in step 5206 determination
Until the threshold value.It is counted in step 5208 record intermediate symbol and resets symbol counter in step 5209.Crosscorrelation step
5210, the step 5213 of the step 5212 and reception new symbol that make symbol counter incremental repeats, until true in step 5211
Until determining to have exceeded the threshold value.If symbol counter counts phase with the intermediate symbol recorded in step 5208 in step 5214
Meanwhile then in 5215 value by frame length return as symbol counter.It will be appreciated that in the example, it can be continuous twice
Frame length is determined after consistent counting.However, required consecutive identical counts can be selected as needed.
Figure 52 B shows a process, even if taking this frame synchronization module 2020 when received signal has very big noise
When also generate the frame-synchronizing impulse of correct timing.The process changes when the interim interruption of signal occurs or in transmitter sending mode
The acquisition also provided when frame_size (frame sign) accordingly changes to new frame synchronization position is provided into.The symbol of free-running operation
Using mould frame_size algorithm to the cell count received, wherein frame_size has passed through retouches counter in conjunction with Figure 52 A
The step of stating determines.It is expected that symbol counter value will always have when the result of 10 crosscorrelation of equation exceeds selected threshold value
Identical value.When the value is consistent, confidence counter is incremented to selected maximum value, such as maximum value 16 upwards；Otherwise make
Confidence counter successively decreases towards zero minimum value.
Therefore, once receiving symbol 5250, crosscorrelation just is executed 5251, if the result 5252 exceeds threshold
Value, then be set to threshold value for current maximum 5253 and maximum point be set to the current value of symbol counter.Show discribed
In example, if confidence counter is set at least 4 value (5254) and current symbol counting indicator frame synchronization point (5255),
Then frame synchronizing signal is exported 5256.Then, symbol counter is incremented by 5257, adds used here as mould 4.It is waited in step 5277
Next symbol, unless being confirmed as zero in step 5270 symbol counter.It, will be current 5271 if symbol counter is zero
Maximum value resetting.Then, if being equal to frame synchronization point in 5272 current maximum points, confidence counter is incremented by and 5273 in step
Rapid 5277 wait next symbol；Otherwise, successively decrease confidence counter 5274.In the example shown at present, if in step
5275 determine that confidence has fallen on 2 hereinafter, frame synchronization point is then set to current maximum point in step 5276.In either case,
Next symbol is waited in step 5277.
To sum up, when confidence counter is beyond predetermined value (value is 4 in this example), frame is same according to the process
Step is confirmed as reliably obtaining.Then frame synchronization module can be cleared in the correct time to provide frame-synchronizing impulse.Such as
Fruit confidence counter is more than 4, and frame-synchronizing impulse will be in orthochronous, and --- beginning for generally corresponding to frame --- is exported, even if
Noise makes equation 10 generate a low value once in a while.
If sending mode changes, final counting is back to zero by confidence counter.This can be used to trigger determining new frame
The frame length of length calculates (such as process using Figure 52 A) again.As discussed below with reference to carrier auxiliary, in recovery
There may be the ambiguities of pi/2 in carrier phase, this will lead to 0, ± pi/2 or any additional recovery phase offset of π.For
Frame synchronization symbol, real and imaginary parts symbol having the same and sends constellation and is illustrated in Figure 39.
Therefore, it will be appreciated that, zero phase is deviated, maximum amplitude bRAnd bISymbol be positive.Such as that of the summary of table 5
Sample, the offset of-pi/2 will generate negative maximum amplitude bRWith positive maximum amplitude bI；Offset for π, bRAnd bIBoth it is negative,
And the offset for pi/2, maximum amplitude bRIt will be positive and maximum amplitude bIIt will be negative.Therefore, maximum amplitude bRAnd bIEach symbol
Number which quadrant that final phase offset has converged in complex plane can be indicated together.This allows in phase offset correction device module
Additional phase correction is applied to signal in 2002 (Figure 20).Maximum value bRAnd bISymbol will from be based on relevant frame synchronization mould
Block 2020 is sent to phase offset connector 2002.
See also Figure 40, the operation of some aspects of the phase offset correction device 2002 in Figure 20 example can be obtained more
Good understanding.LUT 400, which is generated, is based on maximum amplitude bRAnd bISymbol output (being shown in Table 5).Assuming that z [k]=zR[k]+jzI
[k], operation 142 execute as follows:
1) for φ=+ π situation: z ' [k]=- zR[k]-jzI[k]
2) forSituation: z ' [k]=- zI[k]+jzR[k]
3) forSituation: z ' [k]=+ zI[k]-jzR[k]
Once positioning frame synchronization starting position and correcting the offset of m pi/2 phase, just can know that comprising mode bit (star
Seat and trellis code rate) code word position.It can be for example, by BCH decoder or by by the received code word of institute and an all possible code
Word is related and selects the code word for generating highest end value to be reliably decoded to code word.Since the information is repeatedly transmitted,
It therefore can be by requiring same result repeatedly to obtain additional reliability before receiving.Figure 41 is shown can be by frame synchronization mould
One example of such process that block 2020 executes.
The system for continuing Figure 20, the frame synchronizing signal 2021 exported from frame synchronization module 2020 can be used to indicate by symbol
Which symbol is removed before being fed to soft demapper in module 2004.In one example, 127 frames are removed from stream
Sync symbols and 8 mode symbols, this ensures that symbol corresponding with RS grouping is only transferred to soft demapper 2006.It is soft to go to reflect
Emitter 2006 calculates soft bit measurement using algorithm known in the art, and the algorithm includes for example being described by Akay and Tosato
Algorithm.For correct operation, soft demapper 2006 be must be known by transmitter using which kind of perforation pattern (which kind of trellis code speed
Rate) and will also be appreciated that the pattern and received bit alignment.The information 2021 is provided by frame synchronization module 2020, should
In addition 2020 decoding mode information of frame synchronization module simultaneously provides the repetition frame synchronizing signal being aligned with perforation pattern, regardless of current mould
Why is formula.These soft bits measurement is fed to Viterbi decoder 2008, and the Viterbi decoder 2008 is with known in the art
Mode works to obtain the bit estimation for the PTCM encoder being input in transmitter.It is all synchronous by frame synchronizing signal 2010
Derandomized device 2010, byte deinterleaver 2014 and RS decoder 2016 are derandomized respectively, deinterleave and decoded word
Joint number obtains the data for initially entering the encoder of the RS in transmitter accordingly.
Stage switching
Some embodiments are switched using the stage of the estimation of the mean square error based on equalizer output.Balanced device output
The accurate estimation of mean square error (MSE) can be from a series of calculated error es [k] of error calculator module 422 for passing through Figure 42
It obtains.For example, following formula can be used to be estimated:
MSE [k]=(1- β) e2[k]+β MSE [k-1], (equation 18)
Wherein β < 1 is forgetting factor.E [k] other methods being averaging are known and can be used.Equation 18 produces
Raw one as a result, the result can be fallen in compared with predetermined threshold and by the phase controller module 423 of Figure 42 using to work as MSE [k]
From 2 handover operation of stage 1 to stage when below threshold value.Can by MSE [k] compared with the second predetermined threshold to fall on the as MSE [k]
Operation is switched into the stage 3 from the stage 2 when below two threshold values.
Detection is disconnected and is reconnected
Some embodiments provide the system for detecting the disconnection in the camera side of communication link and reconnecting event
And method.Referring again to Figure 51 A and 51B, the signal between modem 511 and 515 may occur in normal work
Partly or entirely disconnect.Certain disconnections influence camera side modems 511 and monitor side SLOC modem 515 it
Between QAM signaling.Specifically, the signal for the image that carrying is captured by HD video camera 510 by the coding of modem 511 and/
Or modulation on cable 514 to be transmitted to display side modem 515.Detection with coaxial cable 514 it is associated disconnection and
A variety of methods of reconnection event can be executed by camera side SLOC modem 511.In response to disconnecting or reconnecting event,
Modem 511 can stop, start or restart downstream passband QAM transmission.In some embodiments, from qam demodulator
" coaxially connected " signal for being sent to QAM modulation device can be used to control the transmission of connection dependent event.
It can be configured to only referring to Figure 53, such as camera side QAM modulation device 530 when coaxially connected signal 531 is by imaging
Downstream passband signal 533 is just sent when pusher side qam demodulator 532 is stated.Camera side qam demodulator 532 can determine input letter
Numbers 534 presence, the input signal 534 are transmitted by monitor side QAM modulation device (not shown) using a variety of methods.In general, working as
When the reception of input signal 534 is reliably confirmed, when confirm constellation mark and/or once obtained frame synchronization verifying when, by
Camera side qam demodulator 532 states coaxially connected signal 531.
A kind of method existing for detection input signal 534 includes the method for being based on automatic growth control (AGC) ring.Including
The AGC found jointly in the communication control processor of qam demodulator is used to control and receive the signal level of different phase and point in machine.
The example described in Figure 27, shows the AGC loop 540 for being added into the receiver front end of Figure 24.In the AGC loop
In 540,541 determine complex signals amplitude and it is subtracted from predetermined reference level 543 542.Pass through low-pass filtering
544 pairs of results of device (LPF) are filtered to inhibit noise and short term variations.LPF 544 provides output, which is fed to packet
Accumulator containing adder 545 and delay cell 546.Accumulator output is used as gain control signal 547, the gain control signal
547 are fed back to the gain block 548 at system input 549.In one example, gain control signal 547 be used as gain because
Several or multiplier, for determining the gain provided by gain block 548 so that the gain provided by gain block 548 is as gain controls
547 increase and increase in predetermined threshold.When input 549 disconnects (such as coaxial cable disconnection), the output of amplitude block 541 is past
It is past very low.In general, coaxially connected signal 531 is only just declared in the case where the output of amplitude block is higher than predetermined threshold.
In addition, gain control signal 547 is usually very high when input 549 disconnects.Therefore, coaxially connected signal 531 is only increasing
Benefit control signal is just declared in the case where being lower than predetermined threshold.AGC loop 540 can be used to monitor the connection status of input 549,
Even if finding loop elsewhere in qam demodulator 532.
It detects another method existing for input signal 534 and is based on balanced device and carrier phase/frequency loop order shown in Figure 43
Section (see also equation 18).Specifically, working as the QAM modulation device phase controller 434 of qam demodulator 532 (at the beginning in the stage 1)
When result based on equation 18 switches to stage 2, coaxially connected signal 531 can be stated.Only in connecting coaxial cable and QAM
When 532 active of demodulator receives stream signal from monitor side QAM modulation device, the transition in stage 1 to stage 2 occurs.Coaxial electrical
Any later disconnection of cable will cause the loss of signal, by the increase of the calculated MSE of equation 18, and will lead to anti-to the stage 1
It is multiple.When qam demodulator 532 is in stage 1, coaxially connected signal 531 can be reset or be de-asserted in other ways.?
In some embodiments, camera side qam demodulator 532 may be required to arrived rank before stating coaxially connected signal 531
Section 3.
Method existing for another kind detection input signal 534 is based on the demodulator frame synchronization confidence for combining Figure 52 B to discuss
Counter.Specifically, coaxially connected signal 531 just may be used only when confidence counter deposit one is greater than the value of predetermined threshold
It is stated by camera side qam demodulator 532.In one example, threshold value can be 4.Therefore, only when connecting coaxial cable and prison
When SLOC frame is sent to video camera by visual organ side modem, coaxially connected signal 531 is just declared.Even if no
Symbol is received, if frame synchronizing process continuation freely carries out, confidence counter counting in reverse can be made and finally make it by disconnecting
Lower than 4, and release the statement to coaxially connected signal 531.
Another method existing for detection input signal 534 is based on higher level protocol.Referring again to Figure 51 A, HD video camera
30 will use gateway protocol to communicate with monitor side host system 38.For the discussion purpose, generally existing internet association
View (IP) will act as an example of gateway protocol.Some modes of IP are intrinsic two-way and cause upstream both with downstream
Send data.If cable disconnects, HD video camera 30 and/or network controller in modem 32 or processor discovery do not have
There is the IP grouping of return just to reach from monitor side and camera side SLOC modem 32 can be notified to stop pass band transfer.?
In one example, these notices may include that special scheduled data grouping is incited somebody to action for example, by MII interface 536 shown in Figure 53 from HD
Video camera 30 is transmitted to modem 32.
The additional information of some aspects of the present invention
Above description of the invention is intended to illustrative and non-limiting.For example, those skilled in that art will be appreciated that,
The present invention can be realized by the various combinations of above-mentioned function and ability, and may include than above-mentioned less or more component.Under
Face illustrates certain additional aspects and feature of the invention, and these additional aspects and feature can be used above in greater detail
Features and parts obtain, as those skilled in that art can appreciate the fact that after being taught by the disclosure.
Certain embodiments of the present invention provides and the associated system and method for video camera.Some packets in these embodiments
Include: processor, the processor receive picture signal from imaging sensor and generate multiple vision signals of characterization picture signal；With
And baseband video signal and digital video signal are combined into the output signal transmitted on cable by encoder, the encoder.?
In some in these embodiments, vision signal includes baseband video signal and digital video signal.In these embodiments
In some, whens combined base band and digital video signal are basic wait.In in these embodiments some, video camera is
Closed circuit high definition television video camera.In in these embodiments some, baseband video signal includes SD analog video signal.?
In some in these embodiments, digital video signal is modulated before combining with baseband video signal.In these embodiments
It is some in, digital video signal includes compressed digital video.In in these embodiments some, digital video signal
It is high-definition digital video signal.In in these embodiments some, the frame rate of digital video signal is lower than picture signal
Frame rate.In in these embodiments some, modulated digital signal is provided to video recorder.
It is some including being configured to the decoder demodulated from the received stream signal of cable in these embodiments.?
In some in these embodiments, demodulated stream signal includes control signal.In in these embodiments some, control
Signal includes the signal for controlling the position and orientation of video camera.In in these embodiments some, control signal includes passing through
Processor controls the signal that baseband video signal and digital video signal generate.In in these embodiments some, control letter
Number include select a part of picture signal to encode as baseband video signal signal.In in these embodiments some,
Controlling signal includes selecting a part of picture signal as the signal of encoding digital video signals.In these embodiments one
In a little, demodulated stream signal includes the audio signal of the audio output for actuated camera.
The system and method for certain embodiments of the present invention offer transmitting video image.Some packets in these embodiments
It includes: making frequency division multiplexing to from the received vision signal of high resolution imaging equipment to obtain modulated digital signal；Passing through will
Modulated digital signal combines to generate output signal with the base-band analog signal of characterization vision signal；And output is believed simultaneously
Number it is transmitted to display system and digital video capture and/or storage equipment.In in these embodiments some, display system is aobvious
Show from the baseband analog of vision signal and characterizes derived image.In in these embodiments some, Digital video storage is used
Digital video recordings device records a series of high definition frames extracted from modulated digital signal.
It is some including compressed video signal in these embodiments.In in these embodiments some, frequency division multiplexing number
The step of word vision signal, includes compressed video signal before modulation.In in these embodiments some, output signal is sent
Including output signal is supplied to coaxial cable.It is some including demodulating from the received input letter of coaxial cable in these embodiments
Number with obtain control signal.Some in these embodiments include by encoding a part of vision signal in composite video signal
In and generate base-band analog signal.Some in these embodiments include being coded in composite video using control signal behavior is quasi-
Part vision signal in signal.Some in these embodiments include the position using control signal control video camera.?
In some in these embodiments, demodulation input signal includes extracting audio signal from input signal.
Certain embodiments of the present invention provides the system and method for running video camera.Some in these embodiments include:
Processor, the processor receive picture signal from imaging sensor and generate multiple vision signals；Control logic, the control logic
It is configured to make a response to by the received control signal of video camera；And modulator, the modulator are configured to modulation digital video
Signal is as modulated signal.In in these embodiments some, multiple vision signals include baseband video signal sum number
Word vision signal.In in these embodiments some, each of multiple vision signals are characterized in camera field extremely
Few a part.In in these embodiments some, the content of control signal control base band and digital video signal.In these realities
It applies in some in example, modulated signal and baseband video signal pass through video camera simultaneous transmission.
In in these embodiments some, whens base band and digital video signal are basic equal.In these embodiments
Some includes encoder, which baseband video signal and modulated signal combine the output signal transmitted on cable.
In in these embodiments some, control signal is received as wireless signal.In in these embodiments some, through adjusting
The signal of system is wirelessly transmitted.In in these embodiments some, digital video signal is high-definition digital video signal.?
In some in these embodiments, digital video signal includes compressed digital video.In in these embodiments some,
Control the mobile ken part by a characterization in vision signal of signal.
Certain embodiments of the present invention provides the balanced device for being used for digital signal and base-band analog signal, the digital signal
It is carried with base-band analog signal by frequency separation and by cable.Some in these embodiments include from the received number of receiver side
The digital equalizer of distortion is removed in word signal.In these embodiments it is some include compensation the analog signal as caused by cable decline
The analog equalizer subtracted.In in these embodiments some, analog equalizer is using one in one group of baseband analog filter
It is a to be decayed with compensating.In in these embodiments some, applied baseband analog filter is based on by digital equalizer
The estimation of calculated decaying difference at different frequencies carrys out selection.
In in these embodiments some, digital signal and analog signal are in the transmitter and reception for being presented as video camera
It is transmitted between machine, wherein the equalizing signal characterized as analog signal is supplied to monitor by receiver.In these embodiments
It is some in, cable includes coaxial cable.In in these embodiments some, distortion increases with cable length.At this
In some in a little embodiments, distortion includes multipath distortion.In in these embodiments some, the estimation of decaying is from having
It is calculated in the frequency range of the substantially linear power spectral density of skew.In in these embodiments some, skew be using
The Fast Fourier Transform of multiple filter taps is calculated.In in these embodiments some, select in frequency range
Frequency band with allow using summation come calculate digital equalizer filter frequency response:
Wherein G [k] is that time domain is received
The Discrete Fourier Transform for the equalizer filter tap held back, and k1Specific frequency band corresponding to DFT.In these embodiments
In some, digital signal includes being characterized by the high definition of the video image of video camera capture, and analog signal includes video image
SD characterization.
Certain embodiments of the present invention provides the electricity for making equally to be carried through the digital signal that frequency is separated with analog signal
The method of analog signal equilibrium in cable.In in these embodiments some, this method is by modem confidence, the modulation
Demodulator receives analog and digital signal and exports baseband video signal.It is some including calculating digital signal in these embodiments
In skew.In in these embodiments some, skew characterizes decaying of the frequency as function to be attributed to cable.These realities
It applies some including making digital signal balanced based on calculated skew in example.It is some including using meter in these embodiments
The skew of calculating is come configure analog equalizer to select in one group of baseband analog filter one.It is some in these embodiments
Including using selected baseband analog filter to carry out balance simulation signal.
In in these embodiments some, analog signal includes baseband video signal and digital signal includes base band video
The high definition version of signal.In in these embodiments some, cable includes coaxial cable, and wherein skew with cable it is long
It spends and changes.In in these embodiments some, skew is originated from multipath distortion.In in these embodiments some, calculate
Skew includes decaying of the estimation in the frequency range for the power spectral density for having skew substantially linear.In these embodiments one
In a little, estimation decaying includes using the Fast Fourier Transform for being directed to multiple filter taps.In these embodiments some
In, estimation decaying includes several frequency bands in selection frequency range.In in these embodiments some, selected frequency band makes to calculate
The efficiency optimization of the step of skew.
Certain embodiments of the present invention provides the digital communication system using novel framing structure.One in these embodiments
A little includes the convolutional byte interleaver of interleaving data frame, and wherein the interleaver is synchronous with frame structure.In these embodiments
Some includes the randomizer for being configured to generate the data frame of randomization from interleaved data frame.It is some in these embodiments
Including the perforation trellis coded modulation device under optional bit rate that works, the perforation trellis coded modulation device is from the data frame through being randomized
Generate the data frame through trellis coding.Some in these embodiments include QAM mapper, and the QAM mapper is by the number of trellis coding
According to the multiple groups bit map in frame to modulated symbol, the frame through mapping thus is provided.In these embodiments it is some include will be same
Step grouping is added to the synchronizer through map frame.
In in these embodiments some, perforation trellis coded modulation device is bypassed to obtain based on the system white noise measured
The optimization net bit rate of performance.In in these embodiments some, identical synchronous grouping is added to a series of subsequent
Each of map frame.In in these embodiments some, identical synchronous grouping is added to each frame through mapping.
In in these embodiments some, the synchronous grouping of a part includes 127 symbols.In in these embodiments some, one
The synchronous grouping in part includes the different binary sequences for the real and imaginary parts of modulated symbol.In these embodiments some
In, the synchronous grouping of a part includes the identical binary sequence for the real and imaginary parts of modulated symbol.In these embodiments
It is some in, synchronous grouping includes the data of transmission mode of the instruction through map frame.In in these embodiments some, transmission
The instruction of mode includes selected qam constellation and selected trellis code rate.In in these embodiments some, system is each
Data frame generate constant integer Reed-Solomon be grouped but regardless of transmission mode why.In these embodiments some
In, system be each data frame generate variable integer modulated symbol but regardless of transmission mode why.In these embodiments
In some, system to each data frame generate the integer perforation pattern period but regardless of transmission mode why.
Certain embodiments of the present invention provides the framing method of variable net bit rate digital communication system.In these embodiments
It is some include that a different set of quadrature amplitude modulation (QAM) constellation is provided.Some in these embodiments include the lattice using perforation
Code character closes to generate the frame of data grouping, and every kind of combination corresponds to associated mode.It is some including mentioning in these embodiments
For the frame with variable integer QAM symbol.In in these embodiments some, QAM code element number corresponds to selected mode.
In in these embodiments some, the associated byte of every frame and Reed-Solomon grouping number are constant.At these
It the use of the frame that perforation trellis code combination generates data grouping include generating integer to each data frame to wear in some in embodiment
The sectional hole patterns period, regardless of associated mode why.In in these embodiments some, the data bit of each QAM symbol
Number is score for one or more modes.In in these embodiments some, for all modes, the trellis coding of every frame
The number in device perforation pattern period is an integer.
Certain embodiments of the present invention provides the system of phase calibration offset.It is some inclined including phase in these embodiments
Shift correction device, the phase offset correction device receive the equalized signal of signal of the characterization through quadrature amplitude modulation and lead from equalized signal
The signal of phasing out.Some in these embodiments include by equalized signal cutting to obtain real number and imaginary number sequence
Second level sheer.Some including frame synchronizer in these embodiments, which executes real number and imaginary number sequence and institute
The correlation of the corresponding portion of the frame synchronization pseudo-random sequence of storage.Some in these embodiments include being supplied to by frame synchronizer
The phase correction signal of phase offset correction device.In in these embodiments some, phase correction signal be based on it is relevant most
Big real number and imaginary value.In in these embodiments some, frame synchronizer holds the incoming quadrature amplitude modulation symbol through cutting
The continuous crosscorrelation of row.
In in these embodiments some, continuous crosscorrelation is using the synchronous PN sequence of binary frame
Stored copies are directed to what real number and imaginary number sequence carried out respectively.In in these embodiments some, the signal through quadrature amplitude modulation
It is using perforation trellis coded modulation.In in these embodiments some, the signal through quadrature amplitude modulation is using quadrature phase shift key
Control system is modulated.In in these embodiments some, the signal through quadrature amplitude modulation (QAM) is modulated using 16-QAM
's.In in these embodiments some, the signal through quadrature amplitude modulation (QAM) is modulated using 64-QAM.In these implementations
In some in example, the frame synchronization symbol symbol having the same of the signal through quadrature amplitude modulation, and relevant maximum real number
With the phase rotation of the symbol instruction equalized signal of imaginary value.In in these embodiments some, provided by frame synchronizer
Phase correction signal include relevant maximum real number and imaginary value symbol.In in these embodiments some, phase is inclined
Shift correction device by indexing there is the look-up table of the symbol of relevant maximum real number and imaginary value to export through phase correction signal,
So that it is determined that phase correcting value.
Certain embodiments of the present invention provides the carrier phase offset in correction receiver in the signal through quadrature amplitude modulation
Method.Some in these embodiments include signal is carried out it is balanced.It is some equalised including cutting in these embodiments
Thus signal obtains real number and imaginary number sequence from equalised signal.It is some including identification real number and void in these embodiments
Frame synchronization sequence in Number Sequence.In in these embodiments some, identification frame synchronization sequence include will be stored it is pseudo- with
Machine sequence is related to real number and imaginary number sequence.In in these embodiments some, identification frame synchronization sequence include from real number
The beginning of frame is determined with the associated maximum related value of imaginary number sequence.It is some including being based on maximum correction in these embodiments
Correct the phase error in equalized signal.
In in these embodiments some, correlation step includes depositing using the synchronous PN sequence of binary frame
It stores up version and continuous crosscorrelation is executed to a succession of quadrature amplitude modulation symbol through cutting.In in these embodiments some, phase
Closing step includes executing continuous crosscorrelation to the storage version of frame synchronization sequence with real number and imaginary number sequence respectively.In these realities
It applies in some in example, the frame synchronization symbol symbol having the same of frame synchronization sequence.In in these embodiments some, school
Plus phase error includes determining phase rotation in equalized signal based on the symbol of maximum related value.In these embodiments
In some, the phase error corrected in equalized signal includes that lookup is indexed with real number and the symbol of imaginary number maximum related value
Table.
Certain embodiments of the present invention provides the method for the carrier phase offset in correction of orthogonal amplitude-modulated signal.At this
In some in a little embodiments, these methods be may be implemented in comprising one or more systems for being configured to the processor executed instruction
In.Some in these embodiments include executing the instruction for being configured to make signal equalization on the one or more processors.These
In embodiment it is some include on the one or more processors execute be configured to cutting equalized signal thus from equalised letter
Number obtain real number and imaginary number sequence instruction.It is some including executing configuration on the one or more processors in these embodiments
At the instruction of the frame synchronization sequence in identification real number and imaginary number sequence.In in these embodiments some, frame synchronization sequence is identified
Column include executing continuous crosscorrelation to the storage version of frame synchronization sequence with real number and imaginary number sequence respectively.In these implementations
Example in it is some in, identification frame synchronization sequence include determining opening for frame from maximum related value associated with real number and imaginary number sequence
Begin.Some in these embodiments include executing to be configured to based on maximum related value correction through equal on the one or more processors
The instruction of phase error in weighing apparatus signal.In in these embodiments some, the frame synchronization symbol of frame synchronization sequence has phase
Same symbol.In in these embodiments some, phase calibration error includes being determined based on the symbol of maximum related value through equal
Phase rotation in weighing apparatus signal.
Certain embodiments of the present invention provides the method for the constellation of identification symbol.It, should in these embodiments some
Method is executed by the one or more processors of the communication system of multimode quadrature amplitude modulation.Some packets in these embodiments
Include the instruction for executing and making the power distribution in one or more processors characterization signal.In in these embodiments some, function
Track to rate distribution statistics the generation of the power level detected in signal.In these embodiments it is some include execute make one
Or multiple processors determine the instruction that one or more peak values of the power level in power distribution occur.In these embodiments
Some includes executing the instruction for making one or more processors determine constellation based on the distribution that peak value occurs.
In in these embodiments some, extension that one or more processors occur also based on one or more peak values
To determine constellation.In in these embodiments some, signal is equalized signal and one or more of processors are logical
The multiple sections crossed in the distribution map for checking power distribution determine constellation.In in these embodiments some, each section
Corresponding to power level range associated with one in multiple constellation candidates but not all constellation candidate.In these realities
It applies in some in example, multiple constellation candidates include quadrature phase keying constellation and quadrature amplitude modulation (QAM) constellation.In these realities
It applies in some in example, multiple constellation candidates include 16-QAM and 64-QAM constellation.It is more in these embodiments some
A constellation candidate includes 256-QAM constellation.
In these embodiments it is some include execute make one or more processors by execute a Continual constellation determine in
Each judgement the step of come establish identified constellation reliability instruction.In in these embodiments some, these steps
It suddenly include being incremented by counter when the identity of subsequent judgement confirmation constellation.In in these embodiments some, these steps
It suddenly include so that counter is successively decreased when subsequent judgement identifies various constellations.In in these embodiments some, these steps
The measurement of reliability is provided including the value based on counter.In in these embodiments some, when counter exceeds a threshold value
When, constellation is identified.In in these embodiments some, a counter is provided for each of multiple constellation candidates,
And the constellation is identified when its corresponding counter exceeds a threshold value.In in these embodiments some, power level
Peak value occurs corresponding to the corner symbol of constellation.In in these embodiments some, constellation is identified before equalizing signal.
Certain embodiments of the present invention provides the constellation of the symbol in the communication system of multimode quadrature amplitude modulation for identification
Method.In in these embodiments some, these methods are that the processor in the modem by communication system executes
's.Some in these embodiments include executing to make processor response in detecting the received data frame at modem
Start and extract from data frame the instruction of pattern information.Some in these embodiments include executing to make processor by from multiple
The code of the corresponding code in closest match pattern bit is selected in potential constellation code and determines the instruction of current constellation.These are implemented
Some in example include executing to make processor increase and before identify if current constellation match with predetermined constellation
The instruction of the associated confidence measure of constellation.If some in these embodiments include executing current constellation and identifying before
Constellation difference, which then executes, to be made processor reduce confidence measure and identifies the instruction of constellation before being recorded as current constellation.These realities
Apply in example it is some include repeating that processor is made to extract pattern information, selection current constellation and for subsequent data frame tune
The step of whole confidence measure is until confidence measure exceeds predetermined threshold.In in these embodiments some, work as confidence level
When amount is beyond scheduled threshold value, constellation is identified.
In in these embodiments some, selecting constellation code includes that execute processor every in multiple potential constellation codes
One with the cross correlation of corresponding code bit.In in these embodiments some, constellation is identified in non-equalizing signal, this is not
Equalizing signal carries the data frame and subsequent data frame.In in these embodiments some, restore in processor from signal
While carrier wave, constellation is identified.Some in these embodiments include executing that processor is made to use constant modulo n arithmetic (CMA)
Error signal is so that equalizer filter tap restrains the instruction for allowing signal equalization.In these embodiments one
In a little, carry out error signal using scaled CMA parameter to improve equalization performance.In in these embodiments some,
The equilibrium for executing signal includes the distribution map for analyzing the power of equalized signal.In in these embodiments some, analysis point
Butut includes using probability mass function.In in these embodiments some, executing signal equalization includes executing to make processor
Calculate the instruction with multiple symbols in equalized signal to associated power.In in these embodiments some, letter is executed
Number equilibrium includes executing the instruction for the corner symbol for making processor and identifying by using threshold power level constellation.In these realities
It applies in some in example, threshold power level indicates the identity of constellation.
Certain embodiments of the present invention provides the system for being used for transmission vision signal, which includes camera side modulatedemodulate
Device is adjusted, which is configured to receive two signals from video camera, and each characterization is by video camera
Captured image sequence, the camera side modem are further configured to a all the way number in two signals as compound
Baseband video signal transmission is simultaneously modulated and is transmitted using another signal as with the nonoverlapping passband vision signal of baseband signal.?
In some in these embodiments, camera side modem includes combination base band and passband vision signal to provide transmission letter
Number mixer.In in these embodiments some, camera side modem includes being configured to send out on transmission line
Send transmission signal and from transmission line extract received passband signal duplexer.In in these embodiments some, take the photograph
Camera side modem includes surveillance camera side modem and generates enabling when received passband signal is identified
The detector of signal.In in these embodiments some, enable in signal control baseband video signal and passband vision signal
The transmission of at least one.
In in these embodiments some, passband vision signal is only just transmitted when generating and enabling signal.At these
In some in embodiment, the received passband signal of institute is by quadrature amplitude modulation.In in these embodiments some, detector monitors
The estimation of mean square error in quadrature amplitude demodulation device, and generated when the estimation exceeds threshold value and enable signal.In these implementations
Example in it is some in, detector monitors constellation detector.In in these embodiments some, enabling signal is based on by constellation
Reliability measurement that detector provides generates.In in these embodiments some, reliability measurement is based on frame synchronization sequence
Column.In in these embodiments some, the valuation of the mean square error in detector monitors balanced device.In these embodiments
In some, when valuation exceeds threshold value, generate and enable signal.In in these embodiments some, detector monitors video camera
Gain factor in the automatic growth control module of side modem.In in these embodiments some, work as gain factor
When with the value for being less than threshold value, generates and enable signal.In in these embodiments some, the received passband of detector monitors institute
The amplitude of signal.In in these embodiments some, when amplitude has the value beyond threshold value, generate and enable signal.At this
In some in a little embodiments, the received passband signal of institute includes the data according to Internet protocol coding.
Certain embodiments of the present invention provides the method for controlling the signaling in security system.One in these embodiments
It include a bit the presence that the composite signal middle and upper reaches QAM signal of transmission over coaxial cable is determined at upstream modem.These
It is some compound including sending upstream modem on coax in the presence of determining upstream QAM signal in embodiment
Baseband video signal and passband vision signal.In in these embodiments some, composite baseband video signal and passband video
Signal is by the parallel characterization of a sequence image of video camera capture.It is some including when determining upstream in these embodiments
So that upstream modem is sent composite baseband video signal on coax in the absence of QAM signal and prevents passband video
The transmission of signal.
In in these embodiments some, when the yield value in automatic gaining controling signal exceeds threshold value, upstream QAM
Signal is confirmed as existing.In in these embodiments some, when the amplitude measurement of upstream QAM signal is less than threshold value, on
Trip QAM signal is confirmed as existing.In in these embodiments some, when the estimation of the mean square error in balanced device exceeds threshold
When value, upstream QAM signal is confirmed as being not present.In in these embodiments some, when identifying net in the QAM signal of upstream
When border protocol data is grouped, upstream QAM signal is confirmed as being not present.
Certain embodiments of the present invention provides the automatic reconfiguration system for being used for transmission vision signal.One in these embodiments
A little includes the upstream modem for being configured to receive two signals from video camera.In in these embodiments some,
Each characterization is by video camera captured image sequence.In in these embodiments some, upstream modem configuration
At using a signal in two signals as composite baseband video signal transmit and using another signal as with baseband signal
Nonoverlapping passband vision signal modulation and transmission.It is some including downstream modem, the downstream tune in these embodiments
Modulator-demodulator is configured to receive composite baseband video signal and passband vision signal from upstream modem and further configure
Upstream modem is transmitted at by upstream passband signal.In in these embodiments some, when detecting upstream passband
When the deterioration of signal, upstream modem stops the transmission of at least one signal in two signals.
Although with reference to certain exemplary embodiments, invention has been described, it is, however, evident that common to this field
It, can various modifications and variations can be made without departing from the wider spirit and scope of the present invention to these embodiments for technical staff.
Such as, it has been described that the system of compressed digital HD video and baseband analog video signals is provided.Of the invention is other
Embodiment provides SD number simultaneously and simulation feeding.Other embodiments are providing full motion digital HD video together with base band
Analog video.Therefore, the specification and drawings are considered as illustrative meaning and not restrictive.
Claims (20)
1. a kind of system for mixed format media transmission, comprising:
First modem is configured to receive one or more vision signals derived from imaging device, first modulation
Demodulator be further configured in the base band of coaxial cable send analog video signal and in coaxial cable with institute
It states in the frequency band of the base band separation of coaxial cable and sends modulated digital video signal, wherein analog video signal and modulated
Digital video signal indicate the video image that is generated by the imaging device；And
Second modem is configured to receive modulated digital video signal from coaxial cable, and demodulates described through adjusting
The digital video signal of system is to obtain high-definition video signal, wherein the high-definition video signal is sent to by second modem
One or more of digital video recordings device, video server and digital display.
2. the system as claimed in claim 1, which is characterized in that further include by the analog video signal and modulated number
The filter of vision signal separation, wherein the analog video signal is provided to SD monitor.
3. the system as claimed in claim 1, which is characterized in that the first modem modulation is derived from imaging device
Compressed vision signal is to obtain modulated digital video signal.
4. system as claimed in claim 3, which is characterized in that one or more vision signals derived from the imaging device
At least one of be by the first modem compress digital video signal.
5. the system as claimed in claim 1, which is characterized in that the second modem modulates control signals upstream, and
The modulated control signal is sent in the channel of the coaxial cable, wherein the modulated control signal passes through institute
It states the first modem to receive and demodulate, and wherein the control signals upstream controls the analog video signal and modulated
One or more of digital video signal content.
6. system as claimed in claim 5, which is characterized in that the control signals upstream determines what the imaging device captured
By a part of the video image of one or more carryings in the analog video signal and modulated digital video signal.
7. system as claimed in claim 6, which is characterized in that the panorama of the modulated digital video signal bearing area
Figure, and wherein the analog video signal carries a part of the panorama sketch.
8. system as claimed in claim 7, which is characterized in that the control signals upstream passes through in control zooming and panning
One or more determines a part of the panorama sketch of the analog video signal carrying.
9. system as claimed in claim 6, which is characterized in that the modulated digital video signal carrying is supervised by video camera
Depending on position the flake visual field, and wherein the analog video signal carries a part in the flake visual field.
10. system as claimed in claim 9, which is characterized in that the control signals upstream leads to the one of the flake visual field
Partial virtual it is mobile.
11. system as claimed in claim 9, which is characterized in that the physics that the control signals upstream passes through starting video camera
It moves to cause the flake visual field to change.
12. a kind of equipment for mixed format media transmission, comprising:
Modem is configured to couple the device to coaxial cable；And
Processing system is coupled to modem and is configured to:
Receive one or more vision signals derived from imaging device；
The modem is caused to send analog video signal in the base band of the coaxial cable；And
The modem is caused to send in the frequency band separated with the base band of the coaxial cable in the coaxial cable
Modulated digital video signal,
Wherein the analog video signal and the modulated digital video signal send simultaneously and indicate to be produced by imaging device
Raw video image, and
Wherein the modulated digital video signal is sent to digital video recordings device, video server and digital display
One or more of.
13. there is a kind of non-volatile memory readable storage medium storing program for executing computer program to be stored in wherein, which works as
Following steps are executed when being run by processor:
Receive one or more vision signals derived from imaging device；
Analog video signal is sent in the base band of coaxial cable；And
Modulated digital video letter is sent in the frequency band separated with the base band of the coaxial cable in the coaxial cable
Number,
Wherein the analog video signal and the modulated digital video signal send simultaneously and indicate to be produced by imaging device
Raw video image, and
Wherein the modulated digital video signal is sent to digital video recordings device, video server and digital display
One or more of.
14. a kind of method for mixed format media transmission, comprising:
One or more vision signals derived from imaging device are received at the first modem；
At least one of one or more of vision signals are modulated to obtain the video figure for indicating that the imaging device generates
The modulated digital signal of picture；
The analog video signal for indicating video image is sent in the base band of coaxial cable；And
In the frequency band separated with the base band of the coaxial cable, modulated number is simultaneously sent with analog video signal is sent
Word signal.
15. method as claimed in claim 14, which is characterized in that the analog video signal and the modulated number view
Whens frequency signal is equal.
16. method as claimed in claim 14, which is characterized in that further include that compression is believed from the received number of the imaging device
Number, to obtain compressed digital signal, wherein at least one of described one or more of vision signals of modulation include
Modulate compressed digital signal.
17. the method described in claim 16, which is characterized in that further include formatting from the received number of the imaging device
For signal to obtain one or more high-definition digital video signals, at least one high-definition digital video signal meets broadcast standard.
18. method as claimed in claim 17, which is characterized in that further include believing from one or more of high-definition digital videos
Number export analog video signal.
19. the method described in claim 16, which is characterized in that further include from from the received digital signal of the imaging device
Export analog video signal.
20. the method described in claim 16, which is characterized in that the digital signal and the compressed digital signal tool
There is different frame rate.
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| US18799609P | 2009-06-17 | 2009-06-17 | |
| US18798009P | 2009-06-17 | 2009-06-17 | |
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| CN201080015700.8A CN102365832B (en) | 2009-01-30 | 2010-02-01 | Mixed format media delivery system and method |
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| CN102365832B (en) | 2016-01-20 |
| KR20110118150A (en) | 2011-10-28 |
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| TW201624997A (en) | 2016-07-01 |
| TWI580272B (en) | 2017-04-21 |
| TW201116058A (en) | 2011-05-01 |
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| CN102365832A (en) | 2012-02-29 |
| CN105704366A (en) | 2016-06-22 |
| KR101674524B1 (en) | 2016-11-09 |
| TWI530190B (en) | 2016-04-11 |
| WO2010088625A1 (en) | 2010-08-05 |
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