JP5940223B2 - Digital transmission system and delay time calculation method - Google Patents

Description

  The present invention relates to a digital transmission system that compresses and digitally modulates and transmits a video signal and an audio signal, and particularly relates to calculation of a delay time of the video signal and the audio signal.

  Video and audio signals were transmitted wirelessly by analog FM methods several years ago. Recently, with the development of digital modulation and demodulation technology, QAM (Quadrature Amplitude Modulation) method and OFDM (Orthogonal) A digital transmission system such as a Frequency Division Multiplexing system is used (see Non-Patent Document 1 and Non-Patent Document 2). At this time, the data to be transmitted is a transmission signal such as TS (Transport Stream) obtained by compressing a video or audio signal by MPEG (Moving Picture Experts Group) processing, but hardly occurred in the conventional analog FM method. Delay time due to compression / decompression processing occurs. Particularly in the operation of broadcasting business, there is a strong demand for a conversation without any discomfort, that is, a so-called delay time, in a conversation between a live broadcast site and a studio.

Against this background, in recent years, it has become possible to reduce the delay time by improving the processing capability of the codec device constituting the compression / decompression process. In particular, the MPEG system has been the mainstream in the past, and according to this system, a delay time of about 15 frames (about 500 ms) has occurred. However, in recent years, H.264, which is more efficient in compression and can be processed with a low delay. The H.264 system is being adopted, and according to this system, a delay time of one frame (about 33 ms) or less can be realized.
The digital transmission methods such as the QAM method and the OFDM method also have a delay time, and mainly include a delay time due to an interleaving process. Interleaving is a method of rearranging the order of sending data so that the characteristics of error correction codes in digital transmission can be obtained sufficiently. Even if an error occurs in the transmission path, the data is returned to the original order on the receiving side. Thus, errors are distributed and error correction becomes effective. In particular, in the OFDM system, a delay time of about 756 ms (corresponding to 23 frames) occurs at the maximum. In the QAM system, it is about 1.3 ms.

  In the broadcasting business, the parameters that cause the delay time described above change according to the operation mode. For example, a mobile relay such as a marathon relay may have a poor transmission path condition due to frequency selective fading and multipath effects, and therefore operates using the OFDM method and uses a longer interleaving time. Further, in order to increase the error correction coding rate, the transmission rate of the main line signal is kept low. As a result, the codec places more importance on the compression efficiency than the delay time. On the other hand, in a transmission line situation with a good line of sight such as a fixed line, the transmission rate of the main line signal can be increased by using the QAM method, so that the operation with lower delay transmission is possible. However, the operator needs to grasp in advance the delay time that changes according to the operation mode.

FIG. 13 shows a system configuration example of a delay time calculation method in the prior art and will be described. The input video signal A1 and the input audio signal A2 are input to the transmission device 1. In the transmission apparatus 1, the input video signal A1 and the input audio signal A2 are compressed and multiplexed by the encoder unit 1-1 to generate a TS signal B, which is supplied to the transmission path encoding unit 1-2. The transmission path encoding unit 1-2 performs error correction encoding processing such as Reed-Solomon encoding, interleaving, and convolutional encoding, and generates an encoded signal C. The digital modulation unit 1-3 performs mapping processing such as 64QAM, 32QAM, 16QAM, and QPSK on the transmission path coded signal C, and then digitally modulates the signal using the QAM modulation or OFDM modulation method. Generated and supplied to the transmission high-frequency unit 1-4.
The IF signal D input to the transmission high frequency unit 1-4 is amplified and frequency up-converted to a microwave band such as 7 GHz and 10 GHz, and a high frequency signal E is generated and output to the field.

FIG. 14 shows an example of a specific configuration of the transmission path encoding unit 1-2, which will be briefly described. B8h substitution unit 1-2-1, energy spreading unit 1-2-2, Reed-Solomon (RS) encoding unit 1-2-3, outer interleaving unit 1-2-4, convolutional encoding unit 1-2 5 and an inner interleaving unit 1-2-6.
In FIG. 14, the input TS signal B is B8h replacing section 1-2-1 with the head word 47h replaced with B8h, energy spreading section 1-2-2 performing energy spreading processing, and RS encoding section 1-1-2. In 2-3, 16 words of error correction parity information are added (Reed-Solomon encoding). By this process, the TS signal is composed of 204 words. Then, an interleaving process, which is a data order rearrangement for effectively performing error correction in the outer interleaving unit 1-2-4, is performed. Since the energy diffusion process described above has a period of 204 words × 8, the first word 47h of the TS signal is converted into B8h once every 8TS periods as a reference. Thereafter, in the convolutional coding unit 1-2-5, the trellis coding process is performed in the case of the QAM system, and the convolutional coding process is performed in the case of the OFDM system (inner coding), and the inner interleaving unit 1-2-6 is performed. In the interleaving process, the data order is rearranged for a longer period than the outer interleaving process. In the case of the QAM scheme, this interleaving process is performed only by convolution time interleaving for rearranging the data order in the time axis direction, and the OFDM scheme is used for bit interleaving, fading, Frequency interleaving for the purpose of reducing the influence of errors due to a drop (dip) in a specific frequency due to multipath interference, and convolution time interleaving similar to the QAM scheme are performed. Returning to FIG. 13, the receiving apparatus 2 will be described. The received high frequency signal E from the transmission device 1 is supplied to the reception high frequency unit 2-1. The reception high-frequency unit 2-1 down-converts the received high-frequency signal E in the microwave band such as 7 GHz and 10 GHz, converts the frequency into a 130 MHz IF signal F, and supplies the converted signal to the digital demodulation unit 2-2.
The digital demodulator 2-2 receives the IF signal F, performs digital demodulation processing by the QAM method or OFDM method, and then performs demapping processing to generate the original encoded signal G. The transmission path decoding unit 2-3 performs error correction processing such as deinterleaving, Viterbi decoding, and Reed-Solomon decoding, and supplies the original TS signal H to the decoder unit 2-4. In the decoder unit 2-4, the video signal and the audio signal are respectively decompressed from the TS signal and are output again as the original output video signal I1 and output audio signal I2.

An example of a specific configuration of the transmission path decoding unit 2-3 is shown in FIG. FIG. 15 is a block diagram showing an example of the configuration of a conventional transmission path decoding unit 2-3, in which processing reverse to that of the transmission path encoding unit 1-2 is performed. In FIG. 15, the input encoded signal G is subjected to a deinterleaving process for returning the data order rearrangement performed in the inner interleaving unit 1-2-6 in the inner deinterleaving unit 2-3-1. Thereafter, the Viterbi decoding processing unit 2-3-2 performs error correction processing based on the information added by the convolutional encoding unit 1-2-5. Thereafter, the outer deinterleaving unit 2-3-3 performs the deinterleaving process for restoring the data order rearrangement, the RS decoding unit 2-3-4 corrects the Reed-Solomon error, and the energy despreading unit 2-3 5, the energy despreading process is performed, and the B8h replacement unit 2-3-6 replaces the first word converted to B8h with 47h once every 8TS periods, thereby obtaining the original TS signal H.
The Reed-Solomon (RS) error correction performed here can be corrected to the original correct word if the error is up to 8 words which is half of the number of additional parity (16 words). However, if the number of error words is 9 words or more, correction is impossible and errors remain.

  Returning to FIG. 13 again, the measuring device 3 will be described. The input video signal A1, the input audio signal A2 and the decoded output video signal I1 and output audio signal I2 output from the reception device 2 are compared with the transmission device 1, and for example, the singular point where the video signal changes is detected with an oscilloscope or the like. When the singular point is detected, the delay time J can be calculated by obtaining the time difference between the input video signal A1 and the input audio signal A2 and the decoded output video signal I1 and output audio signal I2. Become.

The method for measuring the delay time in the prior art described above is such that the input video signal on the transmission side and the output video signal on the reception side are each cabled to one measuring instrument only when the transmission device and the reception device are at a short distance. It was a method capable of measuring the delay time by connecting with each other. However, in actual operation, the transmitting device and the receiving device are at a long distance (several kilometers to several tens of kilometers), and it is difficult to measure using the same connection as described above.
Further, as described above, since the delay time varies depending on the form of operation, measuring the delay time by the above method every time is a very time-consuming work from the viewpoint of work efficiency.

“Portable Microwave Digital Radio Transmission System for Television Broadcast Program Material Transmission” ARIB STD-B11, Japan Radio Industry Association "Portable OFDM digital wireless transmission system for television broadcast program material transmission" ARIB STD-B33, The Japan Radio Industry Association

  The present invention eliminates these drawbacks and automatically detects the delay time without the need for a measuring instrument even if the transmission device and the reception device are at a long distance or the delay time changes depending on the operation mode. It is an object of the present invention to provide a delay time calculation that can be performed.

In order to solve the above-mentioned problems, the present invention provides a transmission side apparatus that compresses a video signal and an audio signal, performs transmission path coding, digitally modulates and transmits the signal, and digitally demodulates a signal received from the transmission side apparatus and combines it. In a digital transmission system consisting of a receiving side device that reproduces video and audio signals by converting and decompressing (whether a GPS signal, quasi-zenith satellite signal, terrestrial digital broadcast signal or atomic clock information signal is received) It has a function to generate absolute time (by having an atomic clock) on the transmitting side and the receiving side, and on the transmitting side, a means for generating timing pulses at a predetermined interval and a time that is synchronized with the timing pulse Means for generating a test audio signal having a pattern, means for compressing the input video signal and the generated test audio signal, and generating a TS (Transport Stream) signal; Before the TS signal is subjected to error correction coding of Reed-Solomon coding, turbo code, or low density parity check code (unique code insertion part of the TS signal of the second embodiment) or after (transmission path of the first embodiment) The encoding unit) inserts an error or a unique code (such as a redundant word) at a time synchronized with the timing pulse at the predetermined interval, and digitally modulates and transmits the received signal on the receiving side. Digital demodulation, error correction decoding of Reed-Solomon decoding, turbo decoding, or low density parity check decoding and before returning to the original TS signal (transmission path decoding unit of the first embodiment) or after (transmission of the TS signal of the second embodiment) Means for detecting an error or a unique code inserted at the predetermined interval in a unique code detection unit), decompressing the decoded TS signal, Means for outputting the test voice signal, means for detecting the singular pattern included in the expanded test voice signal, error correction decoding of the Reed-Solomon decoding, turbo decoding or low density parity check decoding Means for calculating detection time difference information between the time when the error or unique code was detected before or after and the detection time of the specific pattern included in the expanded test audio signal, and the detected detection time difference information and the transmission path Means for calculating a value obtained by adding a known delay time in encoding and digital modulation transmission as a delay time from an input time on the transmission side to an output time on the reception side of the video signal and the test audio signal. It is what I did.
Further, in the above, the singular pattern of the test audio signal generated on the transmission side is a singular pattern in which the amplitude level changes or the frequency changes in synchronization with the timing pulse at the predetermined interval. It is a thing.

In addition, a transmission side device that compresses a video signal and an audio signal, performs transmission path coding, digitally modulates and transmits the signal, and digitally demodulates a signal received from the transmission side device to combine and decompress the video signal and the audio signal. In a digital transmission system comprising a receiving device that reproduces a signal (by receiving a time information signal such as a GPS signal, a quasi-zenith satellite signal, a terrestrial digital broadcast signal or an atomic clock information signal or having an atomic clock) The transmitter and receiver have time generation functions, and receive the time code of the transmitter's absolute time inserted into the video signal during transmission using fixed delay time modulation / demodulation and transmission path encoding / decoding. By subtracting the fixed delay time of ENC / DEC and modulation / demodulation and transmission path encoding / decoding compared with the absolute time on the side, or by superimposing the time code of absolute time on TMCC and comparing it with the reception absolute time, delay Means for calculating time.
Further, in the above, the absolute time time code inserted into the video signal or superimposed on the TMCC has a function of generating an absolute time in the transmitter and means for inserting the absolute time time code into the video signal or TMCC. Or, the imaging device or recording / reproducing device that generates the video signal to be input to the transmitter has the function of generating absolute time and the function of inserting the time code of the absolute time into the video signal. Means for extracting the time code of the time and inserting the extracted time code of the absolute time into the TMCC.

  According to the present invention, the delay time can be automatically detected in the digital transmission system even when the transmitter and the receiver are at a long distance in the digital transmission system or even when the delay time changes depending on the operation mode. With this function, it is possible to automatically calculate the delay time without requiring a measuring instrument.

The block diagram which shows the system configuration | structure of the delay time calculation of one Example in this invention. The block diagram which shows the structure of the timing generation part 1-6 of one Example in this invention The block diagram which shows the structure of the audio | voice test signal generation part 1-5 of one Example in this invention. Audio test pattern generation timing diagram of one embodiment of the present invention The block diagram which shows the structure of the transmission-line encoding part 1-2 of one Example in this invention. Timing chart of error insertion into TS signal of one embodiment of the present invention The block diagram which shows the structure of the transmission-line decoding part 2-3 of one Example in this invention. Error detection processing timing chart from TS signal of one embodiment of the present invention Level detection processing timing chart of the voice pattern detection unit 2-6 according to the embodiment of the present invention. Level detection processing timing chart of the voice pattern detection unit 2-6 according to the embodiment of the present invention. The block diagram which shows the structure of the delay time calculation part 2-5 of one Example in this invention Timing chart of delay time calculation of one embodiment of the present invention The block diagram which shows the system configuration | structure of the delay time calculation method in a prior art Block diagram showing the configuration of the transmission path coding unit 1-2 in the conventional technology The block diagram which shows the structure of the transmission-line decoding part 2-3 in a prior art The block diagram which shows the system configuration | structure of delay time calculation of other one Example in this invention. Schematic diagram of a packet configuration of a unique code (such as a redundant word) inserted into a TS signal according to another embodiment of the present invention Timing chart of unique code insertion and singular point insertion of voice test pattern in TS signal according to another embodiment of the present invention The block diagram which shows the system configuration | structure of delay time calculation of other one Example in this invention. The block diagram which shows the structure of the time code information multiplexing circuit of other one Example in this invention.

Examples of the present invention will be described in detail. FIG. 1 shows an embodiment of a system configuration for delay time calculation according to the present invention.
The input video signal A1 and the input audio signal A2 are input to the transmission apparatus 1. In the transmission apparatus 1, the input audio signal A2 is supplied to the audio timing pattern generation unit 1-5. In the audio timing pattern generation unit 1-5, for example, an audio test pattern having a sine waveform is generated. Is generated.
Here, in the digital transmission system, time information signals such as GPS signals, quasi-zenith satellite signals, digital terrestrial broadcast signals or atomic clock information signals (not shown) are received on the transmission side and the reception side, and on the transmission side and the reception side. Synchronized absolute time information may be shared. In addition, instead of receiving the time information signal by the transmitter on the transmission side of the digital transmission system, the transmission side input video / audio signal generating device (not shown) receives the time information signal and transmits the input video / audio on the transmission side. The time code of the signal may be absolute time information.
In FIG. 1, it is assumed that the timing generation unit 1-6 and the delay time calculation unit 2-5 have atomic clocks, and absolute time information is shared between the transmission side and the reception side.

  FIG. 2 is a block diagram of the timing generator 1-6 in the present invention. The reference clock U from the reference clock generation unit 1-6-1 is input to the counter unit 1-6-2. The counter unit 1-6-2 is a counter circuit synchronized with the reference clock U, and has a predetermined cycle. The timing flag k is output. If the predetermined cycle is an arbitrary cycle longer than the total delay time in the transmission system, for example, a 2-second cycle, there is no problem.

  FIG. 3 is a configuration diagram of the audio timing pattern generation unit 1-5 according to the present invention. FIG. 3A is a configuration diagram in the case of generating a singular pattern in which the amplitude level of the sine waveform voice test pattern changes at the time synchronized with the timing flag k output in the predetermined cycle, and FIG. It is a block diagram in the case of producing | generating the peculiar pattern from which a frequency changes similarly. In FIG. 3A, for example, a sine waveform P of 10 kHz is generated by the sine waveform generator 1-5-1, and the amplitude level is changed at the time synchronized with the timing flag k by the gain switching unit 1-5-2. The peculiar pattern voice signal Q is output. The switching unit 1-5-3 switches the input audio signal A2 and the specific pattern audio signal Q at an arbitrary timing and outputs the audio signal L. In FIG. 3B, a sine waveform generator P 1-5-1 generates a sine waveform P of 10 kHz, for example, and a sine waveform generator 1-5-4 generates a sine waveform R of 5 kHz, for example. The switching unit 1-5-5 outputs the singular pattern audio signal Q whose frequency is changed by switching the sine waveform P of 10 kHz and the sine waveform R of 5 kHz at the time synchronized with the timing flag k. Thereafter, the switching unit 1-5-3 switches the input audio signal A2 and the specific pattern audio signal Q at an arbitrary timing, and outputs the audio signal L. Although the details will be described later, the reason for generating a singular pattern signal in which the amplitude level and frequency are changed as the voice test pattern is that the singular pattern is detected from the output voice signal after decoding on the receiving side. This is so that (time) can be easily found. Further, the switching unit 1-5-3 switches the input audio signal A2 which is a main line signal and the specific pattern audio signal Q and transmits them, but the timing can be at any timing of the operating user, for example, As an off-line work, such as before performing relay transmission, a test operation period for transmitting a singular pattern audio signal Q instead of the main line audio signal A2 and measuring and grasping the transmission delay time in advance is assumed. Yes.

  FIG. 4 shows an audio test pattern generation timing chart according to the present invention. FIG. 4A shows a timing flag k output by the timing generation unit 1-6 every predetermined cycle (Ta′-a: for example, 2 second cycle). FIG. 4B shows a peculiar pattern in which the amplitude level of the sine waveform of, for example, 10 kHz generated by the voice test signal generator 1-5 changes at the times Ta and Ta ′ (for example, the amplitude changes twice). It is a waveform when it has. FIG. 4C shows a waveform when a sine waveform of 10 kHz, for example, has a unique pattern whose frequency changes to, for example, 5 kHz at times Ta and Ta ′. Returning to FIG. 1 again, the input video signal A1 and the audio signal L including the singular pattern input to the encoder unit 1-1 are converted into the MPEG format, H.264, or the like. The signal is encoded by a compression method such as the H.264 method and then packetized, a TS signal B is generated and supplied to the transmission path encoding unit 1-2. The transmission path encoding unit 1-2 performs error correction encoding processing such as Reed-Solomon encoding, interleaving, and trellis convolution encoding, and generates a transmission path encoded signal C.

  FIG. 5 shows an example of a specific configuration of the transmission path encoding unit 1-2 according to the present invention. B8h substitution unit 1-2-1, energy spreading unit 1-2-2, Reed-Solomon (RS) encoding unit 1-2-3, error insertion unit 1-2-7, outer interleaving unit 1-2-4 , A convolutional encoding unit 1-2-5 and an inner interleaving unit 1-2-6. An error insertion unit 1-2-7 is added to the conventional transmission path encoding unit 1-2 shown in FIG. 14, and the other configuration is exactly the same.

  In FIG. 5, the input TS signal B is B8h replacing section 1-2-1 with the head word 47h replaced with B8h, the energy spreading section 1-2-2 is subjected to energy spreading processing, and the RS coding section 1- In 2-3, 16 words of error correction parity information are added (Reed-Solomon encoding). By this process, the TS signal is composed of 204 words. Thereafter, an error is inserted into the Reed-Solomon encoded TS signal at a time synchronized with the timing flag k output at a predetermined interval from the timing generator 1-6 in the error insertion unit 1-2-7. . FIG. 6 is a timing chart for error insertion into a Reed-Solomon encoded TS signal in the present invention. A timing flag k is output at times Ta and Ta ', and an error is inserted in synchronization with the times. The error insertion period can be easily performed by inverting (inverting) data for one word or one bit, for example, and any position in the TS packet 204 words can be used as long as the time is synchronized with the timing flag k. . The error insertion period is, for example, one word or one bit. However, as described above, the error insertion period is an arbitrary period as long as it is 8 words or less that can be corrected by Reed-Solomon error correction on the receiving side.

  Although the details of error insertion on the transmission side will be described later, in the error correction processing on the reception side, the purpose is to correct errors inserted at a predetermined interval and detect the time. This transmission line is assumed to be operated in an error-free line condition with no error error other than the inserted error. In addition, error insertion at a predetermined interval on the transmission side means that errors are detected at a predetermined interval on the reception side. At first glance, it is the same as an error error caused by a normal transmission path failure (error free However, as described above, there is no problem because the operating user is in a test operation for measuring and grasping the transmission delay time in advance as an off-line work before, for example, performing relay transmission. Naturally, the error insertion process is not performed in the production operation in which video and audio signals as main line signals are relayed.

  The TS signal thus error-inserted is subjected to an interleaving process which is a data order rearrangement for effectively performing error correction in the outer interleaving unit 1-2-4. Thereafter, in the convolutional coding unit 1-2-5, the trellis coding process is performed in the case of the QAM system, and the convolutional coding process is performed in the case of the OFDM system (inner coding), and the inner interleaving unit 1-2-6 is performed. In the interleaving process, the data order is rearranged for a longer period than the outer interleaving process. In the case of the QAM scheme, this interleaving process is performed only by convolution time interleaving for rearranging the data order in the time axis direction, and the OFDM scheme is used for bit interleaving, fading, and fading for the purpose of reducing the influence of burst errors in units of carriers. Frequency interleaving for the purpose of reducing the influence of errors due to a specific frequency drop (dip) due to multipath interference, and convolution time interleaving similar to the QAM system are performed.

The digital modulation unit 1-3 performs mapping processing such as 64QAM, 32QAM, 16QAM, and QPSK on the transmission path coded signal C, and then digitally modulates the signal using the QAM modulation or OFDM modulation method. Generated and transmitted to the transmission high-frequency unit 1-3.
The IF signal D input to the transmission high frequency unit 1-3 is amplified and frequency up-converted to a microwave band such as 7 GHz and 10 GHz, and a high frequency signal E is generated and output to the field. Next, the receiving device 2 will be described. The received high frequency signal E from the transmission device 1 is supplied to the reception high frequency unit 2-1. The reception high-frequency unit 2-1 down-converts the received high-frequency signal E in the microwave band such as 7 GHz and 10 GHz, converts the frequency into a 130 MHz IF signal F, and supplies the converted signal to the digital demodulation unit 2-2.

  The digital demodulator 2-2 receives the IF signal F, performs digital demodulation processing by the QAM method or OFDM method, and then performs demapping processing to generate the original encoded signal G. The transmission path decoding unit 2-3 performs error correction decoding processing such as deinterleaving, Viterbi decoding, and Reed-Solomon decoding, and supplies the original TS signal H to the decoder unit 2-4. At this time, in the error correction processing in Reed-Solomon decoding by the transmission path decoding unit 2-3, errors inserted at predetermined intervals on the transmission side are detected, and an error detection flag M is set as a delay time calculation unit. Supply to 2-5. In the decoder unit 2-4, the video signal and the audio signal are respectively decompressed from the TS signal and are output again as the original output video signal I1 and output audio signal I2. In addition, the audio pattern detection unit 2-6 finds a unique pattern inserted on the transmission side from the output audio signal I2, and supplies the audio pattern detection flag N to the delay time calculation unit 2-5. Further, in the delay time calculation unit 2-5, the voice pattern detection flag N from the voice pattern detection unit 2-6 is detected after the error detection flag M detected by the transmission path decoding unit 2-3 is detected. By calculating the time until detection, the delay time in the encoder unit 1-1 and the decoder unit 2-4, and other delay time (excluding the codec time) with respect to the calculated codec delay time information By adding known delay time information corresponding to (transmission path coding, digital modulation / demodulation, delay time in micro line transmission), it becomes possible to obtain delay time information O which is the total delay time in the transmission system. .

  FIG. 7 illustrates an example of a specific configuration of the transmission path decoding unit 2-3 according to the present invention. Inner deinterleaving unit 2-3-1, Viterbi decoding unit 2-3-2, outer deinterleaving unit 2-3-3, Reed-Solomon (RS) decoding unit 2-3-4, energy despreading unit 2 -3-5 and B8h substitution unit 2-3-6. The configuration is basically the same as that of the conventional transmission decoding unit 1-2 shown in FIG. Also in this process, the reverse process of the transmission path encoding unit 1-2 is performed. In FIG. 7, the input encoded signal G is subjected to a reverse interleaving process for returning the data order rearrangement performed in the inner interleaving unit 1-2-6 in the inner deinterleaving unit 2-3-1. Thereafter, the Viterbi decoding processing unit 2-3-2 performs error correction processing based on the information added by the convolutional encoding unit 1-2-5. Thereafter, the outer deinterleaving unit 2-3-3 performs the deinterleaving process for restoring the data order rearrangement, the RS decoding unit 2-3-4 corrects the Reed-Solomon error, and the energy despreading unit 2-3 5, the energy despreading process is performed, and the B8h replacement unit 2-3-6 replaces the first word converted to B8h with 47h once every 8TS periods, thereby obtaining the original TS signal H. In the present invention, it is assumed that the RS decoding unit 2-3-4 corrects an error inserted on the transmission side and outputs an error detection flag M while correcting the Reed-Solomon error.

  FIG. 8 shows error detection (for example, one word or one bit) detected by the RS decoding unit 2-3-4 by detecting data that is inserted into the TS signal by inverting the data at predetermined intervals on the transmission side. FIG. 5 is a timing chart for outputting a flag M. An error is detected at times Ta and Ta ′, and an error detection flag M is output at the same time. Naturally, the error detection interval coincides with the interval at which an error is inserted on the transmission side (Ta′-a: for example, 2 seconds). Further, as described above, since the error insertion period is 8 words or less that can be corrected by Reed-Solomon error correction, all errors inserted into the TS signal on the transmission side are corrected, and then the energy reverse of the subsequent stage is reversed. Supplied to the diffusion unit 2-3-5.

  FIG. 9 shows a singular pattern point (time) at which the amplitude level shown in FIG. 4B is inserted on the transmission side from the decoded output audio signal I2 in the audio pattern detection unit 2-6. FIG. 5 is a timing chart for finding a voice pattern detection flag N. The test pattern generated on the transmission side is, for example, a 10 kHz sine waveform with a change in amplitude level at times Ta and Ta ′ (for example, the amplitude is doubled) at a predetermined period (Ta′-a: for example, 2 second period). Since the waveform has a unique pattern that changes), as shown in FIG. 9, a threshold value is provided for the amplitude level of the detected audio signal, and an audio pattern detection flag N is detected when a value exceeding the threshold is detected. This can be easily realized by adopting a circuit configuration for outputting.

  FIG. 10 is a timing chart in which the voice pattern detection unit 2-6 finds a singular pattern point (time) at which the frequency shown in FIG. 4C changes and outputs a voice pattern detection flag N. . For example, since the sine waveform of 10 kHz has a unique pattern that changes to, for example, 5 kHz at times Ta and Ta ′, as shown in FIG. 9, for example, the threshold with respect to the period between the peaks of the detected sine waveform This can be easily realized by providing a value (0.05 ms for 10 kHz) and outputting a voice pattern detection flag N when a value exceeding the threshold is detected.

FIG. 11 shows an example of a specific configuration of the delay time calculation unit 2-5 in the present invention and will be described. The reference clock S from the reference clock generation unit 2-5-2 is input to the counter unit 2-5-1, and the counter unit 2-5-1 is a counter circuit synchronized with the reference clock S. The counter unit 2-5-1 starts counting from the time of the error detection flag M detected by the RS decoding unit 2-3-4, and is detected by the voice pattern detection unit 2-6. The count is stopped at the time of the voice pattern detection flag N, and the difference information of the count value from the count start to the stop is output as the codec delay time T. As described above, the error detection flag M, which is the count start time, is detected by setting a period longer than the total delay time in the transmission system (for example, a period of 2 seconds). After the detection flag M is detected, before the voice pattern detection flag N that is the count stop time is detected, the error detection flag M that is the next count start time is detected, and thus erroneous detection is performed. Care is taken not to be done.
The codec delay time T calculated in the previous period is transmitted to a delay time other than the known codec delay time (transmission channel coding excluding the codec time, digital modulation / demodulation, micro line, etc.) in the transmission channel delay time adding unit 2-5-3. The known delay time information corresponding to the delay time in transmission) is added, and it becomes possible to output delay time information O which is the total delay time in the transmission system.

  The delay time other than the previously known codec delay time (delay time in transmission path coding, digital modulation / demodulation, and micro-line transmission excluding codec time) will be described in detail below. As described above, as a delay time other than the codec delay time in the transmission system, the delay due to the time interleaving process in the inner interleaving unit 1-2-6 in FIG. 5 and the inner deinterleaving unit 2-3-1 in FIG. I have time. For example, in the OFDM method, the delay time due to the time interleaving process has a plurality of patterns such as 75.6 ms, 378 ms, and 760 ms, and is used properly depending on the operation mode. On the other hand, in the QAM system, it is 1.3 ms, which is only one kind that is very short compared to OFDM. In addition, since the delay time in the other processes is very short in the order of several μs in both the QAM method and the OFDM method, even if each delay time is added, it is a very small processing time that is less than 1 ms. Therefore, you can safely ignore it here. Furthermore, since the unit of the transmission delay time that is normally required can be considered based on the unit of the video signal that is the transmission material (1 frame: about 33 ms), a resolution of ms unit is sufficient. From the above, it can be considered that the delay time other than the known codec delay time is the same as the delay time by the time interleaving process.

FIG. 12 is a timing diagram for calculating the delay time in the present invention, and the overall processing will be described. The horizontal axis represents the signal processing time, FIG. 12A shows the total delay time over the entire transmission system, and FIG. 12B shows the transmission line delay time excluding the codec delay time.
First, (a) at the total delay time, a test pattern having a unique pattern is inserted into the input audio signal on the transmission side, and encoding processing is performed together with the video signal. Thereafter, the transmission path is encoded and digitally modulated and transmitted as a microwave. After receiving the digital demodulation again from the microwave on the receiving side, the transmission path is decoded. Thereafter, decoding processing is performed to obtain the original audio signal and video signal. A unique pattern is detected from the audio signal after the decoding process.
(B) In the transmission line delay time, an error is inserted into the TS signal at the time of transmission line encoding on the transmission side, and digital modulation is performed and the result is transmitted as a microwave. The digital signal is demodulated again from the microwave on the receiving side, and then transmission path decoding is performed. An error is detected from the TS signal during transmission path decoding.
Since the insertion time of the singular pattern in the test audio signal before encoding and the error insertion time in the TS signal at the time of transmission line encoding are the same time processing by the output timing flag described in FIG. 4 and FIG. The time on the time axis of the total delay time and the transmission path delay time coincide.

(B) The time by the counter from the time when the error is detected from the TS signal at the time of transmission line decoding in the transmission line delay time to the time at which (a) the singular pattern is detected from the audio signal after decoding processing in the total delay time The measurement result is equal to the sum of the delay times due to the encoding and decoding processes. That is, it can be regarded as a delay time by the codec. As described above, the transmission line delay time can be regarded as only a delay in time interleaving and is a known value in advance, so that the time measurement result (codec delay time) by the counter and the known transmission line delay time (time The total delay time, that is, the total delay time required from the input and output of the video and audio signals is calculated as the result of adding the delay time in the interleave).
In the present invention, the codec delay time related to the audio signal is obtained by inserting a peculiar pattern into the audio signal as the input material. In a system that encodes, decodes and transmits a video signal and an audio signal called the H.264 system, it is a system managed to decode and output the video and audio signals, usually called lip sync, at the same time (same delay time). Therefore, calculating the delay time of the audio signal is the same as calculating the delay time of the video signal.

Here, the transmission path encoding unit 1-2 performs error correction encoding processing such as Reed-Solomon encoding, interleaving, and trellis convolutional encoding, and the transmission path decoding unit 2-3 performs deinterleaving, Instead of performing error correction decoding processing such as Viterbi decoding or Reed-Solomon decoding, the transmission path encoding unit 1-2 performs error correction encoding processing of a turbo code including interleaving or a low density parity check code Then, the transmission path decoding unit 2-3 performs error correction decoding processing such as turbo decoding including deinterleaving or low density parity check decoding, and performs turbo code or low density parity on the TS signal. It may have a function to automatically detect the delay time by inserting an error or unique code at the time synchronized with the timing pulse at a predetermined interval after performing the check code. .
That is, in the first embodiment, an error occurs at a time synchronized with a timing pulse at a predetermined interval after performing Reed-Solomon coding, error correction coding of a turbo code or a low density parity check code on a TS signal in a digital transmission system. Or, by having a function that makes it possible to automatically detect the delay time by inserting a unique code, even if the transmitter and receiver are at a long distance, even if the delay time changes depending on the operation mode, the measuring instrument The delay time is automatically detected without the need for

Here, in the turbo code, the encoder transmits a bit string as three sub-blocks. The first sub-block is m-bit payload data. The second sub-block is an n / 2 parity bit string of the payload data and is calculated using a recursive systematic convolutional code (RSC code). The third sub-block is a known permutation n / 2 parity bit string of payload data, which is also calculated using an RSC convolutional code. Thus, two redundant but different parity bit sequences are transmitted with the payload. The block length is m + n bits and the code rate is m / (m + n). The rearrangement of payload data uses a device called an interleaver.
Furthermore, in the turbo code, the decoder is also constructed in a similar manner to the encoder, and the two decoders are interconnected, but this is a serial connection and not a parallel connection. The first-stage decoder DEC1 corresponds to the encoder C1, and the second-stage decoder DEC2 corresponds to the encoder C2. DEC1 makes a soft decision, which causes a delay of L1. The same delay occurs with the registers in the interleaver part of the encoder. D EC2 causes a delay of L2. An interleaver is placed between the two decoders to distribute burst errors at the output of DEC1. Of the received signal, xk is directly input to DEC1, but the part corresponding to y1k or y2k is distributed to DEC1 or DEC2 by the demultiplexer.

  The low density parity check code is a linear code, but a sparse matrix is used as the parity check matrix. This sparse matrix is randomly generated.

Only differences between the second embodiment and the first embodiment will be described.
In the digital transmission system, instead of inserting an error or unique code at a time synchronized with a timing pulse at a predetermined interval after performing Reed-Solomon coding on the TS signal of the first embodiment, the TS of the second embodiment is used in the second embodiment. A unique code (redundant word) is inserted at a time synchronized with a timing pulse at a predetermined interval before Reed-Solomon encoding is performed on the signal. That is, the insertion position of the unique code is not performed by the transmission path encoding unit (after the Reed-Solomon encoding unit) but by the TS signal before that. Similarly, the detection position of the unique code on the receiving side is after transmission path decoding as shown in FIG. Similar to the first embodiment, instead of error correction coding processing such as Reed-Solomon coding, interleaving, trellis convolution coding, etc., error correction coding of a turbo code including interleaving or a low density parity check code may be used.
Here, in FIG. 16 of the block diagram showing the system configuration of the delay time calculation method of another embodiment of the present invention, a time information signal such as a GPS signal, a quasi-zenith satellite signal, a terrestrial digital broadcast signal or an atomic clock information signal. Y is received by the transmission side and the reception side, and absolute time information synchronized between the transmission side and the reception side is shared.
FIG. 16 is a block diagram showing a system configuration of a delay time calculation method according to another embodiment of the present invention, and FIG. 16 is a timing chart for inserting a unique code into a TS signal (such as a redundant word) according to another embodiment of the present invention. In FIG. 17 of the schematic diagram of the unique code, only the differences of the second embodiment from the first embodiment will be described.
Unlike the timing generator 1-6 and the delay time calculator 2-5 in FIG. 1 having an atomic clock, the unique code insertion units 1-7 and 2-5 delay time calculators in FIG. In addition, Y of a time information signal such as a GPS signal, a quasi-zenith satellite signal, a digital terrestrial broadcast signal, or an atomic clock information signal is received by the transmitting side and the receiving side.
Configuration and operation of transmission path encoding section 1-2, speech timing pattern generation section 1-5, transmission path decoding section 2-3, speech pattern detection section 2-6, and delay time calculation section 2-5 in FIG. Is the same as that of the first embodiment, and the description thereof is omitted. Also. The audio test pattern generation timing diagram, the TS signal insertion timing diagram, the TS signal detection processing timing diagram, and the delay time calculation timing diagram are also the same as those in the first embodiment, and thus description thereof is omitted.

  In FIG. 16, which is a block diagram showing a system configuration of a delay time calculation method according to another embodiment of the present invention, an input video signal A1 and an input audio signal A2 are input to the transmission apparatus 1. The input video signal A1 input to the transmission apparatus 1 is supplied to the encoder unit 1-1, and the input audio signal A2 is supplied to the audio timing pattern 1-5. The audio timing pattern generation unit 1-8 inserts a specific pattern into the audio signal at a predetermined timing based on absolute time information Y from the unique code insertion unit 1-7 described later.

In the encoder unit 1-1, the input video signal A 1 and the audio signal A 3 generated by the audio timing generation unit 1-8 are MPEG2 or H.264. After encoding by a compression method such as the H.264 method, a TS signal B is generated and supplied to the transmission path encoding unit 1-2. The transmission path encoding unit 1-2 performs error correction encoding processing such as Reed-Solomon encoding, interleaving, and trellis convolutional encoding, and generates a transmission path encoded signal D. The digital modulation unit 1-3 performs mapping processing such as 64QAM, 32QAM, 16QAM, and QPSK on the transmission line encoded signal D, and then digitally modulates the signal using the QAM method or OFDM method to generate an IF signal E in the intermediate frequency band. Then, it is supplied to the transmission high-frequency unit 1-4.
The IF signal E input to the transmission high frequency unit 1-4 is frequency up-converted to a high frequency band such as 7 GHz or 10 GHz, and the amplified high frequency signal F is output to the transmission path.

Next, the receiving device 1 will be described. The received high frequency signal E from the transmitter 1 is frequency-converted by the received high frequency unit 2-1 from the received high frequency signal E of 7 GHz or 10 GHz to the IF signal F of the intermediate frequency band, and the digital demodulator 2-2. Supplied to. The digital demodulator 2-2 performs a digital demodulation process on the IF signal F by the QAM method or the OFDM method, and then performs a demapping process to generate a demapping signal G.
In the transmission path decoding unit 2-3, the demapping signal G is subjected to error correction decoding processing such as deinterleaving, Viterbi decoding, Reed-Solomon decoding, and the like TS signal H similar to the transmitted TS signal is unique. It is supplied to the code detector 2-7. The unique code detection unit 2-7 supplies a timing flag to the delay time calculation unit 2-5 when the identification ID is IFFF indicating redundant data and the data area is unique data designated by the user.
In the decoder unit 2-4, the video signal and the audio signal are respectively decoded from the TS signal H, and the same video signal I1 and audio signal I2 as the transmitter input are output again. The audio pattern detection unit 2-6 detects the timing pattern superimposed on the audio signal I2 and outputs it to the delay time calculation unit 2-5. The delay time calculation unit 2-5 calculates a delay time from the input unique code detection unit M and the audio time signal N, and obtains delay time information O. Using the obtained delay time information, notification to the display device and signal delay correction are performed.

Next, the detailed operation of the unique code insertion and voice timing generation unit on the transmission device side will be described.
FIG. 17 is a schematic diagram of a packet configuration of a unique code (such as a redundant word) to be inserted into a TS signal according to another embodiment of the present invention. The unique code insertion unit 1-7 in FIG. The example of a packet structure of a unique code is shown. The generated packet shown in the example has a packet length of 204 bytes. The 4 bytes of the packet header include a packet identification header in addition to the synchronization byte. A synchronization byte “47” of the TS signal is added to the head of the packet header. (Hereinafter, data is expressed in hexadecimal unless otherwise stated.) Two bytes following the synchronization byte are an identification header indicating a redundant packet. The first 3 bits of 2 bytes are an indicator flag used in the TS, and “0” is set as a default value. The subsequent 13 bits are an additional signal identification ID indicating the contents of the packet. The additional signal identification ID is “1FFF” indicating a redundant packet. As an example. The redundant data does not affect the decoder operation. One byte is used as the control signal used in the TS signal following the identification ID and the cyclic counter, and is set to “10”. Unique information is described in the data area following the packet header. In FIG. 17A, the first 4 bytes are all “00”, and the remaining 180 bytes are all “FF”. The data area of the redundant packet of the encoder output is generally the initial value all “FF”.
FIG. 17B is a timing diagram for inserting a unique code for redundant packets of TS signals. A timing flag k is output at times Ta and Ta ′, and a unique code is inserted in synchronization with the times.

In FIG. 16 of the block diagram showing the system configuration of the delay time calculation method of another embodiment of the present invention, the insertion position of the unique code is not performed by the transmission path encoding unit (after the Reed-Solomon encoding unit). Instead, it is performed with the TS signal in front of it. Similarly, the detection position of the unique code on the receiving side is after transmission path decoding as shown in FIG.
As shown in FIG. 14 of the block diagram showing the configuration of the transmission path encoding unit 1-2 in the prior art, the transmission path encoding unit (after the Reed-Solomon encoding unit) passes through the energy spreading unit, so The original TS signal format collapses, and the PID (Packet Identifier :) shown in FIG. 17 of the schematic diagram of the packet configuration of a unique code (such as a redundant word) inserted into the TS signal of another embodiment of the present invention. It is impossible to identify (NULL detection) such as 13-bit stream identification information indicating the individual stream attribute of the packet.

In FIG. 18 of the timing chart of the unique code insertion and the singular point insertion of the voice test pattern in the TS signal of another embodiment of the present invention, (a) the TS signal is encoded (before transmission line encoding). TS signal is 204 words, TS packet is 204 words, a NULL packet is detected and a unique code is inserted, a unique code is not inserted in the middle of the NULL packet, and a NULL packet is detected after 2 seconds. Insert a unique code.
Further, in the timing flag of FIG. 18B, when a NULL packet of the TS signal is detected and a unique code is inserted, a timing flag is generated.
Further, in the test pattern waveform (amplitude level switching) in FIG. 18C, when a NULL packet of the TS signal is detected, a unique code is inserted, and a timing flag is generated, the test pattern is switched.

  In the second embodiment, the TS signal is synchronized with the timing pulse at the predetermined interval before Reed-Solomon coding, turbo code, or low-density parity check code error correction coding is performed on the TS signal. Even if the transmitter and receiver are at a long distance, even if the delay time changes depending on the operation mode, the error or unique code can be automatically detected. The delay time is automatically detected without the need for an instrument.

Only differences between the third embodiment and the first embodiment will be described.
In digital transmission systems, GPS signals, quasi-zenith satellite signals, terrestrial digital broadcast signals, or atomic clock information signals are received at the transmission side and the reception side at reception, and the transmission side and reception side are synchronized. Explicitly sharing absolute time information. Rather than receiving a GPS signal or a terrestrial digital broadcast signal by a transmitter on the transmission side of the digital transmission system, the input video / audio signal generating device on the transmission side receives and transmits the GPS signal or the terrestrial digital broadcast signal. The time code of the input video / audio signal on the side may be absolute time information.
19 is a block diagram showing a system configuration of a delay time calculation method according to another embodiment of the present invention, and FIG. 20 is a block diagram showing a configuration of a time code information multiplexing circuit according to another embodiment of the present invention. Only the differences between the third embodiment and the first embodiment will be described.
Timing generation unit 1-6, voice test signal generation unit 1-5, transmission path encoding unit 1-2, transmission path decoding unit 2-3, voice pattern detection unit 2-6, and delay time calculation unit 2-5 Since the configuration and operation are the same as those in the first embodiment, description thereof is omitted. Also. The audio test pattern generation timing diagram, the TS signal insertion timing diagram, the TS signal detection processing timing diagram, and the delay time calculation timing diagram are also the same as those in the first embodiment, and thus description thereof is omitted.

The input video / audio signal A is input to the transmitter 1. The input video / audio signal A input to the transmitter 1 is supplied to the time code superimposing unit 1-7 and the time code detecting / generating unit 1-6B. This time code signal is time information used in video and audio equipment synchronization and editing defined in SMPTE (Society of Motion Picture and Television Engineers), and is superimposed on the vertical blanking period of the video synchronization signal. . The minimum resolution of this information is a frame unit indicating “one frame” of the video signal, and other time information includes hour, minute, and second.
A GPS signal and a terrestrial digital broadcast signal are received by the transmission side and the reception side, and absolute time information Y synchronized between the transmission side and the reception side is shared.
In the time code detection / generation unit 1-6B, the time code signal of the input video / audio signal A is detected, and when not superimposed, a transmission time code signal J is newly generated and sent to the time code superposition unit 1-5. Output. The time code detection / generation unit 1-6B generates a time code packet signal L in the TS packet format from the detected time code signal or the generated time code signal, and supplies the time code packet signal L to the digital modulation unit 1-3B.
In the time code superimposing unit 1-7, if the time code signal is superimposed on the input video / audio signal A, the time code superimposing unit 1-7 outputs the signal as it is. If not superimposed, the time code detecting / generating unit 1-6B internally generates it. The time code signal J is superimposed on the input video / audio signal A, and the time code superimposed signal K is output.
The encoder unit 1-1 again separates the time code superimposed signal K into a video signal, an audio signal, and time code information. After encoding by a compression method such as the H.264 method, it is multiplexed with time code information to generate a TS signal B, which is supplied to the transmission path encoding unit 1-2. The transmission path encoding unit 1-2 performs error correction encoding processing such as Reed-Solomon encoding, interleaving, and trellis convolution encoding, and generates a transmission path encoded signal C. In the digital modulation unit 1-3, the time code packet signal L packetized by the time code detection / generation unit is multiplexed on the transmission line encoded signal C, and mapping processing such as 64QAM, 32QAM, 16QAM, and QPSK is performed. Thereafter, digital modulation is performed by the QAM method or the OFDM method to generate an IF signal D in the intermediate frequency band, which is supplied to the transmission high-frequency unit 1-4.
The IF signal D input to the transmission high frequency unit 1-4 is frequency up-converted to a high frequency band such as 7 GHz or 10 GHz, and the amplified high frequency signal E is output to the transmission path.

Next, the receiver 2 will be described. The received high frequency signal E from the transmitter 1 is frequency-converted by the received high frequency unit 2-1 from the received high frequency signal E of 7 GHz or 10 GHz to the IF signal F of the intermediate frequency band, and the digital demodulator 2-2B. Supplied to. In the digital demodulator 2-2B, the IF signal F is digitally demodulated by the QAM method or the OFDM method, and then demapped to generate a demapped signal G. At the same time, the time code packet signal M multiplexed on the main line TS signal is separated and input to the delay time calculation unit 2-5B. In the transmission path decoder 2-3, error correction decoding processing such as deinterleaving, Viterbi decoding, Reed-Solomon decoding, etc. is performed on the demapping signal G, and the TS signal H similar to the transmitted TS signal is decoded. 2-4. In the decoder unit 2-4, the video signal and the audio signal are respectively decoded from the TS signal H, and the video / audio signal I similar to the transmitter input is output again. In the time code detector 2-6, the time code signal N superimposed on the video / audio signal I is separated and input to the delay time calculator 2-5B.
In the delay time calculation unit 2-5B, time information is compared from the input time code / packet signal M and time code signal N, a difference in arrival time is calculated by matching the time, and an operation management unit 2-7 The correction value W, which is a delay time depending on the modulation / demodulation mode input from, is added to obtain delay time information O. Using the obtained delay time information, notification to the display device and signal delay correction are performed.

FIG. 2 shows a time code signal multiplexing circuit in the transmitter. In the time code detection 1-6-1, the time code signal is detected from the input video / audio signal A. When the time code is not superimposed, the time code generation 1-6-2 internally generates the time code J, The time code superimposing unit 1-5 superimposes the input signal. The time code generated here is generated based on the time information of the device and multiplexed on each video frame. If the input video / audio signal A is already time code superimposed, the selection signal X is used as a through output.
In order to make the detected or generated time code signal into a TS signal format that can be transmitted by the apparatus in packetization 1-6-3, a time code packet signal L having a packet structure is generated by adding a synchronization signal and an identification header. And input to the digital modulator 1-3.

The digital modulation unit 1-3B temporarily holds the time code packet signal L in order to match the multiplexed phase of the generated time code packet signal L to the transmission line encoded signal C (1-3-1). The held time code packet signal is sequentially updated to indicate the latest time until an output timing signal P described below is input.
In the redundant packet detection 1-3-2, after detecting the synchronization byte at the head of the packet of the transmission path encoded signal, the redundant packet is determined by identifying the header. An output timing signal P is generated by detecting a redundant packet that is a multiplexing timing of the time code packet, and the time code packet signal held in the holding 1-3-1 is output to the multiplexing circuit 1-3-4. The output held output time code packet signal Q is multiplexed into the main line signal in the multiplexing circuit 1-3-4.
Since the generated output timing signal P has a delay from the synchronization signal phase of the main line signal, the multiplex processing with the phase relationship cannot be performed as it is. Therefore, in order to compensate for the delay of the time code packet signal, the phase adjustment 1-3-3 adjusts the phase of the transmission path encoded signal.
In the multiplexing circuit 1-3-4, the multiplexing process is performed by switching and outputting one packet period of the redundant packet in the main line signal to the holding output time code packet signal Q at the timing indicated by the output timing signal P.
The multiplexed signal output from the multiplexing circuit 1-3-4 is subjected to digital modulation processing such as mapping, QAM, and OFDM in the modulation circuit 1-3-5, and is converted to an intermediate frequency band in the frequency conversion 1-3-6. The IF signal D is output from the digital modulation unit.

  The present invention can be widely applied to detection of delay time in a transmission apparatus such as an FPU, particularly in the case of mobile relay.

1: transmission device, 1-1: encoder unit, 1-2: transmission path encoding unit, 1-3: digital modulation unit, 1-4: transmission high-frequency unit, 1-5: audio timing pattern generation unit, 1- 6: Timing generation unit, 1-7: Unique code insertion unit, 2: Reception device, 2-1: Reception high frequency unit, 2-2: Digital demodulation unit, 2-3: Transmission path decoding unit, 2-4: Decoder unit, 2-5: delay time calculation unit, 2-6: voice pattern detection unit, 2-7: unique code detection unit, 3: measuring instrument 1-2-1: B8h conversion unit, 1-2-2: Energy spreading unit, 1-2-3: RS encoding unit, 1-2-4: outer interleaving unit, 1-2-5: convolutional encoding unit, 1-2-6: inner interleaving unit, 1-2 7: Error insertion unit, 1-6-1: Reference clock generation unit, 1-6-2: Counter unit, 1-5-1: Size Wave generation section, 1-5-2: Gain switching section, 1-5-3: Switching section, 1-5-4: Sine wave generating section, 1-5-5: Switching section, 2-3-1: Within Deinterleaving unit, 2-3-2: Viterbi decoding unit, 2-3-3: outer deinterleaving unit, 2-3-4: RS decoding unit, 2-3-5: energy despreading unit, 2- 3-6: B8h conversion unit, 2-5-1: counter unit, 2-5-2: reference clock generation unit, 2-5-3: transmission line delay time addition unit, 1-3B: digital modulation unit, 1 3-1 ... hold, 1-3-2 ... redundant packet detection, 1-3-3 ... phase adjustment, 1-3-4 ... multiplex circuit, 1-3-5 ... modulation circuit, 1-3-6 ... Frequency conversion, 1-7, time code superposition unit, 1-6B, time code detection / generation unit, 1-6-1, time code detection, 1-6-2, time code generation, 1-6-3 ... packetization, 2-2B ... digital demodulation unit, 2-5B ... delay time calculation unit, 2-5-1 ... hold, 2-5-2 ... comparison, 2-5-3 ... counter stop control, 2-5 -4 ... Counter start control, 2-5-5 ... Counter, 2-5-6 ... Reference clock, 2-5-7 ... Upper limit detection / correction value addition, 2-6B ... Time code detection unit, A1: Input video Signal: A2: input audio signal, B: TS signal, C: encoded signal, D: IF signal, E: high frequency signal, F: IF signal, G: encoded signal, H: TS signal, I1: output video signal , I2: Output audio signal, J: Delay time, K: Timing flag, L: Audio signal, M: Error detection flag, N: Audio pattern detection flag, O: Delay time information, P: Sine waveform signal, Q: Singular Pattern audio signal, R: sine waveform, S: reference clock, T: codec Delay, U: reference clock, V ... update signal, W ... correction value, Y ... time information signal,

Claims (6)

A transmission side device that compresses a video signal and an audio signal, performs transmission path coding, digitally modulates and transmits the signal, and digitally demodulates a signal received from the transmission side device, combines and decompresses the video signal and the audio signal. In a digital transmission system composed of a receiving side device for reproduction, the transmitting side and the receiving side have a function of generating absolute time,
Means for generating timing pulses at predetermined intervals on the transmission side, means for generating a test audio signal having a specific pattern at a time synchronized with the timing pulse, an input video signal, and the generated test audio signal And a means for generating a TS signal, and synchronizing with the timing pulse at the predetermined interval before or after performing the error correction coding of Reed-Solomon coding, turbo code or low density parity check code on the TS signal. Means for inserting an error or unique code at the specified time, digitally modulating and transmitting,
On the receiving side, the received signal is digitally demodulated and error-correction decoded by Reed-Solomon decoding, turbo decoding, or low density parity check decoding and inserted back at the predetermined interval before or after returning to the original TS signal. Or means for detecting a unique code; means for expanding the decoded TS signal and outputting the video signal and the test audio signal; and means for detecting the singular pattern included in the expanded test audio signal And the time when the error or unique code is detected before or after the error correction decoding of the Reed-Solomon decoding, turbo decoding or low density parity check decoding, and the detection of the peculiar pattern included in the expanded test speech signal Means for calculating detection time difference information from time;
A value obtained by adding the detected detection time difference information and a known delay time in transmission path coding and digital modulation transmission, from the input time on the transmission side of the video signal and the test audio signal to the output time on the reception side. And a means for calculating the delay time.   2. The digital transmission system according to claim 1, wherein the singular pattern of the test audio signal generated on the transmission side is a singular pattern in which an amplitude level changes or a frequency changes in synchronization with the timing pulse at the predetermined interval. A digital transmission system comprising a test voice signal generating means. A transmission side device that compresses a video signal and an audio signal, performs transmission path coding, digitally modulates and transmits the signal, and digitally demodulates a signal received from the transmission side device, combines and decompresses the video signal and the audio signal. In the delay time calculation method in the digital transmission system comprising the receiving side device to be reproduced, the transmitting side and the receiving side have a function of generating an absolute time,
At the transmission side, a timing pulse is generated at a predetermined interval, a test audio signal having a unique pattern is generated at a time synchronized with the timing pulse, an input video signal that is a main line signal, and the generated test audio signal To generate a TS signal, perform error correction coding such as Reed-Solomon coding, turbo code or low density parity check code on the TS signal, and synchronize with the timing pulse at the predetermined interval Insert error or unique code, digitally modulate and transmit,
On the receiving side, the received signal is digitally demodulated and subjected to error correction decoding such as Reed-Solomon decoding, turbo decoding or low density parity check decoding, and an error or unique code inserted at the predetermined interval is detected, The decoded TS signal is expanded, the video signal and the test audio signal are output, the singular pattern included in the expanded test audio signal is detected, the time when the error or unique code is detected, and the expansion Calculating the detection time difference information with the detection time of the specific pattern included in the test audio signal,
A value obtained by adding the detected detection time difference information and a known delay time in transmission path coding and digital modulation transmission, from the input time on the transmission side of the video signal and the test audio signal to the output time on the reception side. A delay time calculation method characterized by calculating as a delay time.   4. The delay time calculation method in the digital transmission system according to claim 3, wherein the specific pattern of the test audio signal generated on the transmission side changes in amplitude level or changes in frequency in synchronization with the timing pulse at the predetermined interval. A delay time calculation method characterized by being a unique pattern.   A transmission side device that compresses a video signal and an audio signal, performs transmission path coding, digitally modulates and transmits the signal, and digitally demodulates a signal received from the transmission side device, combines and decompresses the video signal and the audio signal. In a digital transmission system consisting of a receiving side device for playback, the transmitting side and the receiving side have a function for generating an absolute time, and a video signal at the time of transmission using modulation / demodulation of fixed delay time and transmission path encoding / decoding Compare the time code of the absolute time on the transmitting side inserted into the absolute time on the receiving side and subtract the fixed delay time of ENC / DEC and modulation / demodulation and channel coding / decoding, or add the absolute time to TMCC A digital transmission system comprising means for calculating a delay time based on whether a code is superimposed and compared with an absolute reception time. Digital transmission system smell of claim 5 Te, or feed have a function of generating an absolute time signal device, and means for inserting a time code of the absolute time Film image signal or TMCC, or, to the transmitter have a function of inserting the absolute time timecode to function and the video signal to generate an absolute time to the imaging apparatus or a recording and reproducing apparatus to generate a video signal to be input, the time code of the absolute time from the video signal to transmit machine digital transmission system, characterized in that the time code of the extracted extracted absolute time and means for inserting the TMCC.

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