JPH10322302A - Transmission device and transmission / reception method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable broadcast waves of different frequency bands to be received simultaneously by one tuner. SOLUTION: Data P is divided at predetermined time intervals,
The circuit 10a compresses the time axis at predetermined time intervals.
The compressed data is encoded by the circuit 11a, and the compressed data is repeated within the unit. The output of the circuit 11a is modulated at a frequency fc ₁ in circuit 12a, it is supplied to the MUX 13. Data Q and R are similarly modulated at frequencies fc ₂ and fc ₃ , respectively, and supplied to MUX 13. These signals of a plurality of channels are transmitted from the MUX 13 at the same time. On the receiving side, a break is detected from the received signal, the carrier frequency is switched based on this break information, and each signal is demodulated in units of compressed data. The demodulated signal is decoded into compressed data for each channel. The compressed data is distributed for each channel based on the delimiter information, decompressed on the time axis, and output respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting apparatus and a transmitting / receiving method capable of simultaneously receiving radio waves of a plurality of different channels.

[0002]

2. Description of the Related Art At present, satellite broadcasting, which receives radio waves transmitted from a broadcasting station via a communication satellite or a broadcasting satellite, is becoming widespread. In such satellite broadcasting, audio and video signals are digitized into data streams. This data stream is split and packed into packets. A sequence of consecutive packets is called a transport stream. The transport stream is modulated in a predetermined frequency band, and is used for communication satellites or broadcast satellites (hereinafter, these are collectively referred to as “satellite”).
Sent to.

[0003] A satellite is equipped with a plurality of repeaters called transponders. Each of the transponders covers a different frequency band. Thus, a single satellite can simultaneously relay a plurality of broadcasts having different frequency bands. The transmission radio waves described above are relayed by a transponder having a corresponding frequency band, and received by a receiver.

[0004] In order to realize conditional access to broadcasting in reception of satellite broadcasting, an IRD (Integrated Broadcasting) is used.
Receiver Decoder) is used. The IRD includes a tuner for specifying a receiving transponder, a demodulator, a descrambler for descrambling, a demultiplexer for specifying packets to be separated, an image decoder, an audio decoder, and the like. Controls supply.

[0005]

Conventionally, when two broadcasts relayed by one satellite and transmitted in different frequency bands from each other are to be simultaneously received, two broadcasts are required.
There was a problem that two tuners had to be provided in order to demodulate broadcast waves in two different frequency bands.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a transmitting apparatus and a transmitting / receiving method capable of simultaneously receiving broadcast waves in different frequency bands with one tuner.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a transmitting apparatus for simultaneously transmitting a plurality of data streams by modulating the plurality of data streams at different carrier frequencies. And a retransmitting unit that repeats an output corresponding to each of the plurality of data streams within a predetermined time interval unit. Having retransmission means, modulation means for modulating outputs corresponding to each of the plurality of data streams at mutually different carrier frequencies, and transmission means for simultaneously transmitting outputs corresponding to the plurality of data streams, respectively, of the modulation means. A transmission device characterized in that:

Further, in order to solve the above-mentioned problem, the present invention modulates a plurality of data streams at mutually different carrier frequencies and transmits them simultaneously, receives and demodulates transmitted signals, and demodulates a plurality of data streams. In the transmission / reception method for restoring, each of a plurality of data streams supplied simultaneously is divided at predetermined time intervals, and a compression step of compressing the time axis in units of time intervals, and a compression step, each of the plurality of data streams. A retransmission step of repeating a corresponding output within a predetermined time interval unit, a retransmission step, a modulation step of modulating an output corresponding to each of the plurality of data streams with a different carrier frequency, and a modulation step. A transmitting step of simultaneously transmitting an output corresponding to each of the plurality of data streams; Receiving the signal transmitted in the step of transmitting, receiving the signal transmitted in the step of transmitting, and the carrier switching step of switching the carrier of a different carrier frequency in synchronization with the delimiter of the received signal, the carrier A demodulation step of demodulating a signal received based on the demodulation method, and a step of switching an output of the demodulation step in synchronization with carrier switching.

As described above, according to the present invention, each of a plurality of data streams is divided into predetermined time intervals,
Time axis compression is performed at a predetermined time interval unit, and the compressed data is repeated within the predetermined time interval unit, and each of the plurality of data streams is transmitted at a different carrier frequency. At the time of reception, the carrier frequency at the time of demodulation is switched based on a predetermined time interval of the received signal, and the demodulated output is cyclically switched for each different carrier frequency. Therefore, a receiving device having one tuner can simultaneously receive a plurality of channels having different carrier frequencies.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. FIG. 1 and FIG. 2 show an example of the configuration of a transmission / reception system according to this embodiment. In the transmitting apparatus 1 shown in FIG. 1, each of a plurality of data is modulated at a different carrier frequency to be a signal of a plurality of channels. These signals of the plurality of channels are transmitted to the communication path 30 at the same time. These transmitted signals are received in parallel by the receiving device 2 shown in FIG. 2 to obtain an output for each channel.

In FIG. 1, a plurality of data streams (data streams P, Q, and R) are supplied to a transmitting apparatus 1 as baseband signals. These data streams are delimited at predetermined time intervals, as shown in FIG. 3A. Each divided section is referred to as a segment slot. That is, the segment slots are switched at the predetermined time intervals. The data stream P will be described. The data stream P is divided into segment slots, and the data stream P, which is sequentially data 1, data 2, data 3,... Supplied.

The compression circuit 10a compresses the supplied data stream P in the time axis direction by a predetermined method for each segment slot. As shown in FIG. 3B,
Since the data stream P is compressed for each segment slot, a blank portion occurs in each segment slot in the time axis direction. In this example, the data of each segment slot is compressed to 1/6 with respect to the time axis. Note that this compression ratio is not limited to 1/6, and other values can be selected. The output of the compression circuit 10a is supplied to a coding / retransmission circuit 11a.

The coding / retransmission circuit 11a includes a coding section and a retransmission section. The supplied compressed data is first encoded in the coding unit. For this encoding, for example, MPEG (Moving Picture Expert)
s Group) 2 system is used. The compressed data encoded by the coding unit is supplied to the retransmission unit, and is repeated a predetermined number of times for each segment slot and output from the coding / retransmission circuit 11a. FIG. 3C schematically shows this output signal. Thus, for each segment slot, the compressed data corresponding to that slot is repeated. This means that the same compressed data is retransmitted a plurality of times from the transmission side. For example, as shown in FIG. 3C, compressed data 1 obtained by compressing data 1 is repeated in the segment slot designated as data 1 in FIG. 3A. The number of repetitions is preferably determined according to the compression ratio of the compression circuit 10a. In this example in which the compression ratio is 1/6, the number of repetitions is six.

[0014] Hereinafter, the section of the break for each compressed data is referred to as a compression slot. The division of the compression slot corresponds to the division of the segment slot in the signal source from the viewpoint of data.

The output of the coding / retransmission circuit 11a is supplied to a modulation circuit 12a. The modulation circuit 11a, modulates the data supplied by the carrier frequency fc _1, and outputs. The output of the modulation circuit 11a is a signal of the channel Ch1. The signal of the channel Ch1 is supplied to the multiplexer (MUX) 13.

On the other hand, data streams Q and R are subjected to the same processing as data stream P. That is, as shown in FIG. 4A, the data stream Q is divided into segment slots and compressed by the compression circuit 10b.
Supplied to The output of the compression circuit 10b (FIG. 4B) is supplied to the coding / retransmission circuit 11b, encoded by a predetermined method, and the compressed data is repeated for each segment slot. That is, as shown in FIG. 4A, data A, B, C,... For each segment slot is time-compressed and repeated, and as shown in FIG. Are repeatedly arranged to form a compression slot. The output of the coding / retransmission circuit 11b is supplied to a modulation circuit 12b for performing modulation with the carrier frequency fc _2. The compressed data modulated by the modulation circuit 12b is converted into a signal of the channel Ch2 and supplied to the multiplexer 13.

The processing for the data stream R is the same as that for the streams P and Q described above. The data stream R is, as shown in FIG. 5A, data a, b, c,.
c to form data as shown in FIG. 5B, and the coding / retransmission circuit 11c repeats the compressed data,
It is a compression slot as shown in FIG. 5C. The output of the coding / retransmission circuit 11c is supplied to the modulation circuit 12c, it is modulated by the carrier frequency fc _3, Channel C
The signal of h3 is supplied to the multiplexer 13.

The coding / retransmission circuits 11a, 1
The encoding in 1b and 1c is not limited to the same method. For example, the circuits 11a and 11
In b, encoding may be performed by MPEG2 and MPEG1, respectively, and encoding may not be performed by the circuit 11c. Although the path of the encoding information is omitted in FIG.
Supplied to

Although not shown, the multiplexer 13 has a transmission circuit, and includes modulation circuits 12a, 12b, and 12c.
The signals of the channels Ch1, Ch2, and Ch3 respectively supplied from are transmitted to the communication path 30 at the respective carrier frequencies by this transmission circuit. It is preferable that the signals of the respective channels be synchronized with each other in the segment slot because the processing on the receiving side is simplified.

At the time of transmission, a predetermined marker, for example, a predetermined pulse signal or a signal in a non-signal state (such as a signal of level 0 in a predetermined period) is added in accordance with the switching position of the compression slot. This is preferable because switching of the compression slot can be easily detected on the receiving side. At the same time, at the time of transmission, by adding the coded information by the coding / retransmission circuits 11a, 11b, and 11c to the corresponding signals, the receiving side can support various coding schemes. preferable.

The communication path 30 is, for example, via a communication satellite or a broadcasting satellite, and the transmitted signal is transmitted by a transponder corresponding to each carrier frequency. Of course, it is possible to transmit on different channels of the same transponder. In addition, the communication path 30 may be a terrestrial wave, or a wired one.

The signal transmitted via the communication path 30 is received by the receiver 2 shown in FIG. When the signal is transmitted by radio waves, it is received by an antenna (not shown). When transmitted by wire, it is received by a modem (not shown) or a predetermined interface.

The received signal is supplied to a demodulation circuit 21 and a slot detection circuit 20. The slot detection circuit 20 detects switching of the compression slot from the received signal. The switching position of the compression slot corresponds to a break for each compression slot.
This detection result is supplied to the channel changer 23. The carrier of the frequency fc_var is supplied from the channel changer 23 to the demodulation circuit 21. The frequency fc_var is cyclically switched to the frequencies fc ₁ , fc ₂ , and fc ₃ every time the compression slot is switched based on the detection result of the slot detection circuit 20.

[0024] As an example of the detection method according to the slot detecting circuit 20, the slot detecting circuit 20 has a simple tuner that is fixed to the frequency fc ₁ corresponding to the tuning frequency, for example, channel Ch1, the supplied signal The added marker indicating the switching of the compression slot is detected.

The demodulation circuit 21 has a tuner section for receiving at a predetermined tuning frequency and a demodulation section for demodulating a received signal (not shown), and performs signal reception and demodulation. In the demodulation circuit 21, the channel changer 23
(Carrier frequency fc_va supplied from
Perform demodulation using r). Thereby, the demodulation circuit 21
In, the carrier frequency is cyclically switched for each compression slot, and reception and demodulation are performed for each channel Ch1, Ch2, and Ch3 in units of compression slots.

In practice, a certain amount of time is required for the circuit to stabilize with the switching of the carrier frequency, and thus a signal is lost. Therefore, each channel C
The signals of h1, Ch2, and Ch3 are intermittently received in the order of compression slots. For example, FIG.
The compression slots indicated by the circles in C, FIG. 4C, and FIG. 5C are received. The received signals are respectively demodulated and output.

FIG. 6 schematically shows the output of the demodulation circuit 21. As shown in the drawing, compressed data 1, blank, compressed data A, blank, compressed data a, blank, compressed data 2, blank, compressed data B,.
The signals of No. 3 are output from the demodulation circuit 21 intermittently in order of compression slots.

The output of the demodulation circuit 21 is the multi-purpose decoder 2
2 is supplied. In the slot detection circuit 20, the coded information added to the received signal is also detected. This encoded information is supplied to the multipurpose decoder 22 via the channel changer 23. Multipurpose decoder 22
Has various decoding processes, and decodes the output of the demodulation circuit 21 in a corresponding manner based on the supplied encoding information.

The output of the multipurpose decoder 22 is supplied to a demultiplexer 24. This demultiplexer 24
For example, as shown in FIG. 2, three output terminals 24a, 2a
4b and 24c. The switch circuit is switched based on the detection result of the switching of the compression slot, which is detected by the above-described slot detection circuit 20 and supplied via the channel changer 23. In this demultiplexer 24, the compression slots distributed for each of the channels Ch1, Ch2, and Ch3 are stored in the time axis expansion / output processing circuit 2 respectively.
5a, 25b, and 25c.

Time axis expansion / output processing circuits 25a, 25
b and 25c comprise a time axis decompression unit and an output processing unit. In the time axis expansion unit, the compression circuit 10 of the transmission device 1
The time axis expansion corresponding to the time axis compression performed in a, 10b, and 10c is performed. Each channel Ch1, Ch
The signals 2, 3 and Ch3 are time-expanded in each of the circuits 25a, 25b, and 25c and are returned to the baseband signal. These signals are subjected to predetermined signal processing, and output the channel Ch1 and the channel C, respectively.
h2 output and channel Ch3 output are output.

As described above, by using the present invention, one tuner can receive a large number of channels having different carrier frequencies in parallel. Therefore, for example, a so-called picture-in-picture (hereinafter, referred to as “PinP”), in which a child screen, which is another video area, can be displayed in a parent screen and two screens, a parent screen and a child screen, are displayed in one screen. ") And a so-called picture and picture (hereinafter abbreviated as" P & P ") in which one screen is divided into left and right sides to be a main screen and a sub-screen, respectively, and different images are projected. The present invention can be applied to this.

In a television receiver to which this PinP is applied, conventionally, for example, two tuners are provided, and images of different channels are displayed on the main screen and the child screen. By using such a television receiver, the user causes the currently selected channel to be displayed on the main screen, the other channels to be displayed on the sub-screen, and the main screen and the sub-screen to be viewed simultaneously. be able to. Also, in a television receiver to which P & P is applied, conventionally, for example, two tuners are provided, and images of different channels are projected on the main screen and the sub-screen.

A television broadcast is broadcast based on the configuration of the transmitting apparatus 1 according to the embodiment, and the configuration of the receiving apparatus 2 is applied to a television receiver, thereby providing a television having one tuner. The above-mentioned PinP and P & P functions can be realized by the John receiver.

In the transmitting apparatus 1, the data stream P is audio data, the data stream Q is video data, and the data stream R is binary data such as program data, for example, for each of the channels Ch1, Ch2, and Ch3. Different types of data may be transmitted. The data transmitted in this manner is separated by the demultiplexer 24 and output. The audio data of the channel Ch1 is subjected to predetermined processing by the time axis expansion / output processing circuit 25a, and is reproduced by, for example, a speaker. Similarly, the video data of the channel Ch2 is supplied to a display device or the like, and an image is displayed. The binary data of the channel Ch3 is written on a recording medium such as a hard disk.

In the above description, the data stream is compressed on the time axis for each segment slot and retransmitted in order. However, the present invention is not limited to this example. In the transmission of a data stream that has no real-time property and the time series is not particularly problematic, for example, the transmission of program data, time axis compression and decompression are not essential. Further, in this case, an operation of rearranging data at the output stage is possible. Therefore, even if several segments are collectively retransmitted and transmitted in one repetition cycle, data can be restored on the receiving side.

Further, in the above description, the coding / retransmission circuit 11a is arranged at the subsequent stage of the compression circuit 10a in the transmitting apparatus 1, and the encoding is performed after performing the time axis compression. However, this is limited to this example. Not something. For example, in the data stream P, the coding / retransmission circuit 1
1a may be separated into a coding circuit 11a 'and a retransmission circuit 11a ", and a compression circuit 10a may be provided at a subsequent stage of the coding circuit 11a', and a retransmission circuit 11a" may be provided at a subsequent stage. The data stream P is supplied to a coding circuit 11a 'and is first coded.

In this case, the configuration of the receiving apparatus 2 is changed correspondingly, and the time axis expansion / output processing circuit 25a
Are separated into a time base expansion circuit 25a 'and an output processing circuit 25 ", and a time base expansion circuit 25a' is provided instead of the multipurpose decoder 22. The output end 24a of the demultiplexer 24 is connected to the multipurpose decoder 22. The output of the decoder 22 is supplied to the output processing circuit 25 ″.

[0038]

As described above, according to the present invention, in the transmitting apparatus, the data stream is time-axis-compressed for each segment slot at each of a plurality of carrier frequencies, and the same data is repeatedly retransmitted. In the receiving device 2, the receiving channel is switched in accordance with the segment slot that has been transmitted after being compressed on the time axis. Therefore, there is an effect that one tuner can receive a plurality of channels having different carrier frequencies in parallel.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a configuration of a transmission device according to an embodiment.

FIG. 2 is a block diagram illustrating an example of a configuration of a receiving device according to the embodiment;

FIG. 3 is a schematic diagram schematically illustrating an example of data handled by a transmission device and a reception device.

FIG. 4 is a schematic diagram schematically illustrating an example of data handled by a transmission device and a reception device.

FIG. 5 is a schematic diagram schematically illustrating an example of data handled by a transmission device and a reception device.

FIG. 6 is a schematic diagram schematically showing an output of a demodulation circuit.

[Explanation of symbols]

10a, 10b, 10c ... compression circuit, 11a, 11
b, 11c... coding / retransmission circuit, 12a, 1
2b, 12c modulation circuit, 13 multiplexer, 20 slot detection circuit, 21 demodulation circuit, 22 multipurpose decoder, 23 channel changer

Claims (2)

[Claims] 1. A transmitting apparatus for modulating a plurality of data streams at mutually different carrier frequencies and simultaneously transmitting the plurality of data streams, wherein each of the plurality of data streams supplied at the same time is divided at predetermined time intervals, Compression means for performing time axis compression; retransmission means for repeating output corresponding to each of the plurality of data streams within the predetermined time interval unit of the compression means; and each of the plurality of data streams of the retransmission means And a transmitting means for simultaneously transmitting outputs corresponding to each of the plurality of data streams of the modulating means. 2. A transmission / reception method for modulating a plurality of data streams at different carrier frequencies and transmitting them simultaneously, receiving and demodulating the transmitted signals, and restoring the plurality of data streams, wherein the plurality of data streams are simultaneously supplied. A compression step of separating each of the plurality of data streams at a predetermined time interval and compressing the time axis in units of the time interval; and outputting the output of the compression step corresponding to each of the plurality of data streams to the predetermined time interval. A step of repeating retransmission within an interval unit; a step of modulating an output corresponding to each of the plurality of data streams at a carrier frequency different from each other; and a step of modulating the plurality of data in the step of modulation. A transmitting step of simultaneously transmitting an output corresponding to each of the streams; A step of receiving the transmitted signal in the step of transmitting, and a step of switching a carrier that switches the carrier having the different carrier frequency in synchronization with the delimiter of the received signal; and A transmission / reception method, comprising: a demodulation step of receiving a signal and demodulating the received signal based on the carrier; and a step of switching an output of the demodulation step in synchronization with the carrier switching.