JPH0771270B2 - Multiplexing device for TV camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention connects a television camera or a camera adapter connected to the television camera and a base station by a single transmission line to provide a video signal, a return video signal, The present invention relates to an apparatus for transmitting and receiving various signals such as a synchronously coupled signal by a frequency division multiplexing method, and more particularly to improvement of an apparatus for transmitting a synchronously coupled signal for establishing synchronization between a base station and a television camera side.

(Prior Art) FIG. 3 is an explanatory diagram showing a frequency arrangement of a conventional multiplex transmission device for a television camera.

The video signal VS, the synchronous coupling signal SYC, the return video signal VR, etc. are transmitted via a single transmission path 140 such as a coaxial cable provided between the camera adapter 120 connected to the television camera 110 and the base station 130. A device 100 that multiplex-transmits various video meter signals, various control signals, and audio signals by frequency division is known.

FIG. 4 is a block diagram of a main part showing a configuration of a portion related to a video signal in a conventional multiplexer.

The television camera 110 is a video signal processing circuit 11 that converts an image captured by the image sensor 112 via the optical system 111 into a video signal VS.
3 and a display control unit 115 that controls the display contents of the monitor display unit 114 provided in the viewfinder, and monitors the image currently captured by the monitor display unit 114 or the return video sent from the master station side. It is configured to be able to.

The camera adapter 120 includes a video signal modulation circuit 121 that converts the video signal VS into a predetermined frequency band, and a frequency multiplexing circuit 122.
Return video signal VR and sync combination signal input via
Synchronization for generating various synchronization signals such as horizontal synchronization, vertical synchronization, and subcarrier frequency signal based on the demodulation output of the return image signal demodulation circuit 123 for demodulating SYC, the synchronous combination signal demodulation circuit 124, and the synchronous combination signal demodulation circuit 124. A signal generation circuit 125 is provided.

The base station 130 includes a modulation circuit 131 for the return image signal VR, a demodulation circuit 132 for the video signal VS, and a modulation circuit 13 for the synchronous combined signal SYC.
3, and frequency multiplexing circuit 134. Synchronous combined signal
The SYC uses a composite color sync signal that is a composite of horizontal / vertical sync signals, horizontal / vertical blanking signals, and color burst signals.

(Problems to be Solved by the Invention) As described above, in the conventional television camera multiplex transmission device, in order to synchronize between the television cameras 110 and 120 side and the base station 130 side, the synchronization coupling signal SYC is transmitted through a dedicated channel. Sending and receiving. For this reason, the synchronous coupling signal modulation circuit 133 that converts the synchronous coupling signal SYC to a specific frequency is transmitted to the base station 130 side, and the synchronization that demodulates the frequency-multiplexed synchronous coupling signal SYC is transmitted to the camera adapter 120 side. Combined signal demodulation circuit 124
Are required respectively. Therefore, the circuit scale is large and the device is large.

Also, since a composite color sync signal is used as the sync combination signal SYC, a wide frequency band is required to send the sync combination signal SYC (9 MHz or more band when sending the NTSC composite color synchronization signal by AM modulation). Therefore, the frequency utilization efficiency when frequency multiplexing is poor.

The present invention has been made to solve such a problem, and an object thereof is to return a part of the signal necessary for the synchronous coupling as a video signal transmission channel without providing a modulation / demodulation circuit dedicated to the synchronous coupling signal. It is an object of the present invention to provide a multiplex transmission device for a television camera capable of reducing the circuit scale and narrowing the band of the multiplex transmission line.

(Means for Solving the Problems) In order to solve the above problems, a television camera multiplex transmission apparatus according to the present invention is provided with at least a horizontal scanning synchronous coupling signal HX and a subcarrier designation signal.
In addition to frequency multiplexing transmission of SCX, it performs frequency multiplexing transmission of the sync coupling signal SYX before the synchronization with the camera (camera adapter) 2 side and the return video signal VR after the synchronization is established from the base station 3 side to the camera 2 side. After establishing synchronization with the base station 3 side on the basis of the synchronous coupling signal SYX transmitted from the station 3 side, at least a video camera multiplex transmission device 1 for performing frequency multiplex transmission of a video signal from the camera 2 side to the base station 3 side And the camera 2 is based on the video signal transmitted from the camera 2 side.
A synchronization establishment detection circuit 36 that detects establishment of synchronization with the side and outputs a synchronization establishment detection signal 36a, and outputs the return video signal VR instead of the synchronization coupling signal SYX based on the synchronization establishment detection signal 36a (selection circuit 31 A horizontal scanning signal based on the horizontal scanning synchronous coupling signal HX transmitted from the base station 3 side and the base station 3 side, which includes a signal generating circuit (composed of the return video signal / synchronization coupling signal modulation circuit 32). Horizontal scanning signal generation circuit 27
And a color subcarrier signal generation circuit (subcarrier signal generation circuit) 26 for generating a color subcarrier signal (subcarrier frequency signal) SC based on the subcarrier designation signal SCX transmitted from the base station 3 side, and horizontal scanning The camera 2 side provided with a synchronizing signal generating circuit 28 that generates at least a vertical synchronizing signal based on the signal (horizontal scanning frequency signal) HS, the color subcarrier signal SC, and the synchronizing combined signal 23a transmitted from the base station 3 side. It is characterized by having.

(Operation) The base station frequency multiplex-transmits the horizontal scanning synchronous coupling signal and the subcarrier designation signal, and frequency-multiplexes the synchronous coupling signal to the camera side until synchronization with the camera side is established.

The horizontal scanning signal generation circuit on the camera side generates a horizontal scanning signal based on the horizontal synchronization combined signal transmitted from the base station side. The color subcarrier signal generation circuit on the camera side generates a color subcarrier signal based on the subcarrier designation signal transmitted from the base station side. The synchronization signal generation circuit on the camera side converts the sync combination signal transmitted from the base station side, the horizontal scanning signal generated by the horizontal scanning signal generation circuit, and the color subcarrier signal generated by the color subcarrier signal generation circuit. At least a vertical synchronizing signal is generated based on the above.

As a result, the camera side frequency-multiplexes and transmits the video signal based on the designation from the base station side to the base station side.

The synchronization establishment detection circuit on the base station side outputs a synchronization establishment detection signal when it detects that synchronization has been established between the base station side and the camera side based on the video signal transmitted from the camera side.
Based on this synchronization establishment detection signal, the signal generation circuit on the base station side stops the transmission of the synchronous coupling signal and instead frequency-multiplexes the return video signal.

Until the synchronization between the base station side and the camera side is established, the return video signal channel can also be used to send out the sync combination signal, so there is no need for a modulation / demodulation circuit for sending and receiving the sync combination signal. In addition, since a channel dedicated to synchronously coupled signal transmission with a wide band is not required, the frequency band required for the multiplex transmission path can be narrowed.

Since the horizontal scanning synchronous coupling signal and the subcarrier designation signal are continuously transmitted, the synchronization state once established is maintained unless the base station requests signal system switching from NTSC system to PAL system, for example. It

(Embodiment) An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of the essential parts of a television camera multiplex transmission apparatus according to the present invention.

This television camera multiplex transmission device 1 connects a camera adapter 2 connected to a television camera (not shown) and a base station 3 by a transmission line 4 using one coaxial cable or the like, and 4 is configured to transmit and receive a plurality of frequency-multiplexed signals. The camera adapter 2 may be provided inside the television camera.

FIG. 2 is an explanatory diagram showing the frequency arrangement of frequency multiplex transmission.

FIG. 2 shows an example of transmitting and receiving a TV signal conforming to the NTSC system. The DC power is supplied from the base station 3 to the camera adapter 2 side, and the horizontal scanning synchronous coupling signal HX, subcarrier designation signal SCX, control signal, and audio signal are frequency-divided and transmitted in a band up to about 3.3 MHz. . The horizontal scanning synchronous coupling signal HX is horizontally transmitted between the base station 3 or a master station side (hereinafter referred to as the base station side) that controls a plurality of base stations and the TV camera or the camera adapter 2 side (hereinafter referred to as the camera side). It is a signal for matching the scanning frequency fH and synchronizing the phase. In this embodiment, the horizontal scanning frequency of the NTSC system is 15.73 kHz, which is 29 times the frequency (about 456 kHz).
Is used.

The subcarrier designation signal SCX is a signal for synchronizing the frequency and phase of the color subcarrier SC between the base station side and the camera side. In this embodiment, NTSC color subcarrier frequency fSC
It uses half the frequency (about 3.58MHz). Further, the sub-carrier designation signal SCX is transmitted from the base station side to the camera side, depending on whether the sub-carrier designation signal SCX is AM-modulated at a low frequency (for example, 1 kHz) or not.

The control signal is a signal for remotely operating the camera side from the base station side, the voice signal is for extension call from the base station side to the camera side, and the control signal and the voice signal are each 2 channels. It is provided.

From the camera side to the base station side, the subcarrier frequency signal SC generated on the camera side within the frequency range of about 3.4MHz to 47MHz.
S and 2 channels of audio signal for extension call, 1 channel of audio signal related to video, and video signal VS picked up by a television camera are transmitted by band division.

In this embodiment, two types of color difference signals of RY and BY and a luminance signal Y are provided independently of each other by using an NTSC type composite color signal for the video signal VS by independently providing three channels. The video signals of various systems other than the NTSC system can be transmitted.

Further, in the band of about 47 MHz to 63 MHz, the synchronization coupling signal SYX is transmitted from the base station side to the camera side until the synchronization is established, and the return video signal VR is transmitted after the synchronization is established. The video signal V
S, the return video signal VR, and the synchronous combined signal SYX are transmitted by AM modulation, and various audio signals are transmitted by FM modulation. Further, the horizontal scanning synchronous combined signal HX, the subcarrier designation signal SCX, and the subcarrier frequency signal SCS are transmitted in a narrow band by using a continuous sine wave of a predetermined frequency, and a circuit that does not require a modulation / demodulation circuit is provided. We are trying to reduce the scale.

FIG. 1 shows the configuration of a portion relating to the video signal VS, the return video signal VR, and the signals HX, SCX, SYX related to the synchronous coupling.

The camera adapter 2 is a video signal captured by a TV camera.
A video signal modulation circuit 21 for converting VS into a signal in a predetermined frequency band, and a frequency multiplexing circuit 22 which is a coupling portion with the transmission path 4.
And a return video signal / synchronous combined signal demodulation circuit 23 for demodulating the return video signal VR or the synchronous combined signal SYX input via the frequency multiplexing circuit 22, and a supply destination of the output signal 23a of the demodulation circuit 23 is switched. The switching circuit 24 and the sub-carrier designation signal SCX sent from the base station 3 side are detected whether they are AM-modulated at a predetermined low frequency (for example, 1 kHz).
AM modulation non-modulation identification circuit 25, subcarrier signal generation circuit 26,
A horizontal scanning signal generation circuit 27 and a synchronization signal generation circuit 28 are provided.

In the state where the synchronization between the camera side and the base station side is not established, the above-mentioned AM-modulated subcarrier designation signal SC from the base station side is sent.
X is sent out, and in this state, the output 23a of the return video signal / synchronization combined signal demodulation circuit 23 is based on the identification output 25a of the AM modulation / non-modulation identification circuit 25 to the synchronization combined signal input terminal 28a of the synchronization signal generation circuit 25. Control the switching circuit 24 to be supplied,
When the synchronization is established and the unmodulated subcarrier designation signal SCX is transmitted from the base station side, the AM modulation non-modulation identification circuit 25
The output circuit 25a is configured to control the switching circuit 24 so that the logical level of the output 25a is inverted and the output 23a of the return video signal / synchronous combined signal demodulation circuit 23 is supplied to the television camera side.

The subcarrier signal generation circuit 26, based on the frequency and phase of the subcarrier designation signal SCX applied to the input terminal 26a,
Output terminal for color subcarrier frequency signal SC synchronized with the base station
The signal is output to 26b. In this embodiment, it is composed of a PLL circuit that generates a signal having a frequency twice that of the signal applied to the input terminal 26a. This PLL circuit has a configuration capable of following over a wide frequency range so that the color subcarrier frequency signal SC of 4.43 MHz can be generated when the frequency of the subcarrier designation signal SCX is 4.43 / 2 MHz of the PAL system, for example. There is. Color subcarrier frequency signal SC output to output terminal 26b
Are supplied to the synchronization signal generation circuit 28.

The horizontal scanning signal generation circuit 27 outputs the horizontal scanning frequency signal HS synchronized with the base station side at a frequency of 1/29 of the frequency of the horizontal scanning synchronization combined signal HX applied to the input terminal 27a to the output terminal 27b. , A frequency divider circuit, a PLL circuit and the like. This P
The LL circuit is also configured to follow over a wide input frequency range so as to generate a signal of another horizontal scanning frequency. Horizontal scanning frequency signal H output to output terminal 27b
S is supplied to the synchronization signal generation circuit 28.

The synchronization signal generation circuit 28 is provided with means for measuring each cycle of the color subcarrier frequency signal SC and the horizontal scanning frequency signal HS input to the input terminals 28b and 28c and determining the video signal system requested by the base station side. Various synchronization signals corresponding to the signal system (for example, NTSC, PAL, etc.) based on the judgment result, or
The base station side is configured to output to the output terminal 28d various synchronizing signals corresponding to a video signal system designated through a control signal channel (not shown). For example, when the request from the base station side is the NTSC system, this synchronization signal generation circuit 28
It generates horizontal sync signals of 15.73 kHz, vertical sync signals of about 60 Hz, and various sync signals such as horizontal and vertical blanking period signals and color burst signals.

Further, in the case of the NTSC system, the synchronizing signal generating circuit 28 outputs a sine wave signal SCS synchronized with the color sub-carrier signal SC generated by the sub-carrier signal generating circuit 26 to the output terminal 28e, and outputs the sine wave signal SCS at the frequency. It is transmitted to the base station side via the multiplexing circuit 22. When the PAL system is required, this synchronizing signal generation circuit 28 generates various vertical / horizontal synchronizing signals corresponding to the PAL system and also performs amplitude modulation of the color subcarrier with the RY color difference signals. The color subcarrier frequency signal S for the PAL system in which the polarity of the color subcarrier is inverted for each scanning line required for
C (PAL) is generated, and the sine wave signal of the frequency including the polarity inversion information and generated by the subcarrier signal generation circuit 26
The SCS (PAL) is transmitted to the base station side via the frequency multiplexing circuit 22.

Furthermore, when the sync coupling signal SYX is applied to the input terminal 28a, the sync signal generating circuit 28 inverts the vertical sync timing designated by the sync coupling signal SYX, and in the case of the PAL method, every scanning line is inverted. Generates a horizontal sync signal and subcarrier frequency signal SC based on the polarity of the color subcarrier, and maintains the sync state until a new sync join signal SYX is applied even if the sync join signal SYX is no longer applied. Configured to do so.

The base station 3 includes a selection circuit 31 for selecting either the return video signal VR or the synchronous coupling signal SYX supplied from a master station (not shown), and a return circuit for converting the selected signal into a signal in a predetermined frequency band. Video signal / Synchronous combined signal modulation circuit 32
And a frequency multiplexing circuit 33 which is a coupling portion with the transmission path 4, and a video signal VS sent from the camera side through a predetermined channel.
Video signal demodulation circuit 34 for demodulating the
Sync signal extraction circuit 35 for extracting various vertical and horizontal sync signals and color burst signals from the sync signal, and various sync signals extracted by the sync signal extraction circuit 35 and the sync signal SYN supplied from the master station are synchronized. A synchronization establishment detection circuit 36 for determining whether or not the state is the established state is provided. Based on the synchronization establishment detection signal 36a output from the synchronization establishment detection circuit 36, the selection circuit 31 is switched so as to select the synchronization combination signal SYX in the state of establishment of the synchronization end and the return video signal VR after the establishment of synchronization, and , By controlling the AM modulation operation of the AM modulation non-modulation circuit 37 based on this output 36a, before synchronization is established, a signal obtained by modulating the subcarrier designation signal SCX with a low frequency signal (for example, 1 kHz) An unmodulated subcarrier designation signal SCX is transmitted to the camera side via the frequency multiplexing circuit 33. Further, the base station 3 is configured to send the horizontal scanning synchronous coupling signal HX supplied from the master station or the like to the camera side via the frequency multiplexing circuit 33.

Subcarrier designation signal SCX and horizontal scan synchronous combined signal HX
Uses a continuous sinusoidal signal to perform narrowband transmission without sidebands. In this embodiment, as the frequency of the subcarrier designation signal SCX, a value of 1/2 of the color subcarrier frequency is used. This is to detect the establishment of synchronization on the base station 3 side by returning the color carrier frequency signal SCS generated on the camera adapter side 2 to the base station 3 side at the same frequency without converting it to another frequency signal. For ease of explanation, the frequency of the color carrier designation signal SCX is set to another value. Therefore, the subcarrier designation signal SCX may be any signal that includes information about the color subcarrier frequency and its phase.

In the case of the NTSC system, the frequency of the horizontal scanning synchronous combined signal HX is about 456 kHz, which is 29 times the horizontal scanning frequency of 15.73 kHz.
By using a high frequency, the influence of noise from the power supply due to the DC component is reduced and the transmission loss is reduced, and the frequency can be set appropriately.

The synchronization establishment detection circuit 36 is a circuit for identifying whether or not the subcarrier frequency signal SCS input to the input terminal 36b is synchronized with the color subcarrier signal in the sync combination signal SYX supplied from the master station side. I have it. In the case of the NTSC system, it is possible to identify whether the frequency and phase of the color subcarrier are synchronized based on the color burst signal extracted by the sync signal extraction circuit 35. Since the polarity of the carrier is inverted, the polarity is checked based on the subcarrier frequency signal SCS input via the frequency multiplexing circuit 33 of the transmission line 4.

Then, until synchronization is established, a synchronous coupling signal SYX containing information related to vertical synchronization and, in the case of the PAL method, information designating its polarity is sent to the camera side using the channel for the return video signal. Is configured as follows.

Since the camera adapter 2 has the above-described configuration, the sub-carrier signal SC and the sub-carrier signal SC generated by the signal generating circuits 26 and 27 based on the sub-carrier designating signal SCX and the horizontal scanning synchronization combined signal HX sent from the base station 3 side are first described. Based on the horizontal scanning frequency signal HS, various synchronizing signals including vertical synchronizing signals at appropriate timings are generated by the synchronizing signal generation circuit 28 and supplied to the television camera, and the resulting video signal VS is supplied to the base station. Frequency multiplex transmission to the side.

The synchronization establishment detection circuit 36 in the base station 3 is the camera adapter 2
Since it detects that the video signal VS sent from the side is not synchronized with the reference synchronization signal SYN of the master station, the base station 3
Sends the synchronous coupling signal SYX to the camera adapter 2 side through the channel for the return video signal, and AM-modulates the subcarrier designation signal SCX to transmit the synchronous coupling signal SYX to the camera adapter 2 side. Let us know.

When the camera adapter 2 side detects that the subcarrier designation signal SCX is AM-modulated, the demodulation output of the channel for the return video signal is input to the synchronization signal generation circuit 28 and transmitted from the base station 3 side. Vertical synchronization is established based on the synchronization combination signal SYX (in the case of the PAL system, the polarity of the color subcarrier for each horizontal scanning line is also adjusted to the designation of the base station side), and various types of synchronization are established. The sync signal is supplied to the TV camera side.

When the base station 3 side confirms by the synchronization establishment detection circuit 36 that the video signal VS sent from the TV camera side completely matches the timing requested by the master station side, the base station 3 side originally uses the channel for the return video signal. Send the return video signal VR,
The subcarrier designation signal SCX is returned to the non-modulation state.

The AM modulation / non-modulation identifying circuit 25 in the camera adapter 2 detects that it is in a non-modulation state, and switches the switching circuit 24 so that the return video signal VR is supplied to the television camera side. Therefore, in the viewfinder of the TV camera, the image of another TV camera connected to the master station, the image captured by this TV camera sent back by the master station, or the video selected by the master station. By displaying, it is possible to confirm that the synchronization between the camera and the base station or the master station has been established.

If synchronization is lost for some reason, or if the broadcasting system is changed on the master station side, the synchronization coupling signal SYX using the return video signal channel is sent and received again to reestablish synchronization. Done.

In this embodiment, it is assumed that there is a master station that controls a plurality of TV cameras and the like, and the broadcasting system designated by this master station is
Although the example of synchronizing the television camera side with the synchronizing signal has been described, the present invention is also applied to the case of connecting to a video signal recording device such as a video tape recorder (VTR) of various systems via the base station 3. be able to.

Further, the portion for generating the broadcasting system designation and the reference synchronization signal may be provided in the base station 3.

(Effects of the Invention) As described above, the television camera multiplex transmission apparatus according to the present invention transmits the synchronous coupling signal via the channel for the return video signal to achieve synchronization between the camera side and the base station side. Since the synchronous coupling signal is transmitted and received, the number of modulation circuits and demodulation circuits can be reduced, the size and cost of the device can be reduced, and the frequency band required for multiplex transmission can be narrowed. It is possible to relax the frequency characteristics required for.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of a multiplex transmission device for a television camera according to the present invention, FIG. 2 is an explanatory view showing a frequency arrangement of the same device, and FIG. 3 is a frequency arrangement of a conventional multiplex device for a television camera. FIG. 4 is a block diagram showing the essential parts of a conventional multiplexer. 1 ... Multiplex transmission device for television camera, 2 ... Camera adapter, 3 ... Base station, 4 ... Transmission line, 21 ... Video signal modulation circuit, 23 ... Return video signal / synchronization combined signal demodulation circuit,
24 …… Switching circuit, 25 …… AM modulation / non-modulation discrimination circuit, 26 ……
... Sub-carrier signal generation circuit, 27 ... Horizontal scanning signal generation circuit, 28 ... Synchronization signal generation circuit, 31 ... Selection circuit, 32 ...
Return video signal / synchronization combined signal modulation circuit, 34 ... video signal demodulation circuit, 35 ... synchronization signal extraction circuit, 36 ... synchronization establishment detection circuit, HS ... horizontal scanning frequency signal, HX ... horizontal scanning synchronization combined signal , SC …… color subcarrier frequency signal, SCS …… sine wave signal synchronized with color subcarrier, SCX …… subcarrier designation signal, SYN …… synchronization signal, SYX …… synchronous combination signal, VR …… return video signal , VS …… video signal.

Claims (1)

[Claims] 1. At least a horizontal scanning synchronous combined signal and a subcarrier designation signal are frequency-multiplexed and transmitted, and a synchronous combined signal before establishing synchronization with the camera side and a return video signal after establishing synchronization from the base station side to the camera side. Frequency-multiplex transmission, and after establishing synchronization with the base station side based on the synchronous coupling signal transmitted from the base station side, at least video signal frequency-multiplex transmission from camera side to base station side A device for detecting synchronization establishment with the camera side based on the video signal transmitted from the camera side and outputting a synchronization establishment detection signal, and the return image based on this synchronization establishment detection signal. A horizontal scanning signal based on the horizontal scanning synchronous coupling signal transmitted from the base station side, and a base station side including a signal generating circuit that outputs a signal in place of the synchronous coupling signal. A horizontal scanning signal generation circuit, a color subcarrier signal generation circuit for generating a color subcarrier signal based on the subcarrier designation signal transmitted from the base station side, the horizontal scanning signal and the color subcarrier signal A television camera multiplex transmission device comprising: a camera side having at least a vertical synchronizing signal generating circuit for generating a vertical synchronizing signal based on the synchronously coupled signal transmitted from the base station side.