JP2015173337A - Transmitter, receiver and check bit number determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve video transmission with few errors fixed, satisfying predetermined transmission quality without decreasing transmission efficiency.SOLUTION: A transmitter 1 includes: a check bit number determination unit 12 for setting the number of initial check bits which is common to all channels, acquiring a transmission quality index for each channel observed at the reception side, and determining the number of check bits, obtained by increasing or decreasing the number of initial check bits, on the basis of each channel; and an error correction coding unit 11 for granting check bits, having the above number of check bits, to the input video signal on the basis of each channel, to perform error correction coding. The check bit number determination unit 12 determines the number of check bits in such a manner that the number of check bits is increased as the transmission quality indicated by the transmission quality index is worse, and the total number of check bits for all channels becomes equal to the product of the number of channels and the number of initial check bits.

Description

  The present invention relates to a transmission apparatus that transmits an error correction code of a video signal, a reception apparatus that receives a signal from the transmission apparatus and performs error correction decoding, and a method for determining the number of check bits of a correction code.

  In recent years, the development of 4K and 8K Super Hi-Vision (SHV) is progressing as ultra-high-definition video exceeding Hi-Vision. For example, in the case of transmitting uncompressed material signals to the broadcasting station in SHV, one high-definition video with 7680 samples x 4320 lines per video frame is transmitted with 12-bit quantization, RGB 4: 4: 4 format, and frame frequency 60 Hz. Then, the information transmission speed of the video data reaches about 72 Gbps. As a method for transmitting a video signal having an extremely large capacity as described above, there is a method for transmitting an original video signal by dividing and multiplexing the original video signal into a plurality of optical signals. Patent Document 1 describes a method for improving the quality of a received signal by applying error correction coding to each of signals obtained by further dividing a video signal.

  On the other hand, in an optical fiber transmission system, a wavelength division multiplexing (WDM) transmission technique in which optical signals having a plurality of wavelengths are multiplexed is widely used in order to realize large-capacity transmission (see, for example, Patent Document 2).

  FIG. 10 shows a WDM video signal transmission system using a conventional error correction code. A plurality of signals configured by dividing a video signal are subjected to error correction coding with the same error correction code type and the same redundancy for each signal by the error correction coding unit in the transmission apparatus 100. . Thereafter, the E / O conversion device 200 performs electrical / optical conversion, and outputs N optical signals having different wavelengths. When the transmission speed of the video signal input to the transmission device is the same, each optical signal has the same transmission speed.

  N optical signals are multiplexed into one optical fiber by the wavelength multiplexing filter 300. In the transmission line, an amplifier 400 is installed in the middle of the line as necessary, and the signal is transmitted while being relayed. This is to satisfy desired quality on the receiving side while compensating for transmission loss in the optical fiber used as the transmission path when transmitting the target distance.

  On the receiving side, the optical signal is separated into N optical signals by the wavelength separation filter 500 and optical / electrical conversion is performed by the O / E converter 600. Thereafter, in the receiving device 700, the error correction decoding unit detects and corrects the error bit of the received optical signal to restore the video signal.

  Here, as one of the transmission quality indicators, there is an SNR value defined by a ratio between received signal power and noise power. FIG. 11 shows an image of bit error rate (BER) characteristics with respect to SNR. In the WDM video signal transmission system shown in FIG. 10, by applying the error correction code, it is possible to improve the BER at the same SNR value compared to the case where the error correction code is not applied. The amount of improvement varies depending on the type of error correction code and the redundancy. Also, the broken line in the figure is an SNR value (required SNR value) that satisfies a desired BER when a video signal is transmitted with a certain amount of information, and the transmission system is designed so that the actual SNR value exceeds the required SNR value. .

JP 2012-239123 A JP-A-9-261205

  When a plurality of optical signals are multiplexed and transmitted, the transmission parameters (information rate, error correction coding method, optical output, etc.) of the optical signal of each channel are usually the same. The SNR value of the electrical signal of the receiver after O / E conversion is the output signal level of the transmitter, the loss of the transmission line (≈transmission distance), the noise emitted by the amplifier (≈the number of relay amplifiers), the optical transmission line It is determined by various factors such as non-linear signal degradation and thermal noise in the receiver.

  FIG. 12 is a diagram showing the SNR after signal transmission in the case of 3 channels. In an optical transmission line, the SNR may not be uniform between channels due to the dependency of the wavelength used for transmission. In the example shown in FIG. 12, the SNR value a of channel 1 <the SNR value b of channel 2 <the SNR value c of channel 3. In this case, since it is necessary to design the transmission system so that the entire video signal to be transmitted has fewer errors, the SNR value a which is the smallest SNR value satisfies the required SNR value (exceeds the required SNR value). To design.

When the target transmission distance is given, the following two types of design methods can be considered.
<First Method> The level of the output signal of the transmission apparatus is increased to reduce the number of relay amplifiers and increase the SNR value.
<Second Method> By increasing the redundancy in error correction coding of a plurality of signals constituting a video signal, the amount of improvement in BER is increased and the required SNR value is decreased.

  However, in the first method, for example, by reducing the number of relay amplifiers (≈reducing noise power), the SNR is improved. However, the amount of power amplified by the reduced amplifier is reduced by the output signal of the transmission apparatus. There is a problem that transmission efficiency decreases if it is made up by increasing the level. The transmission efficiency is the transmission signal power for transmitting 1 bit of information of the entire transmission system. That is, when the transmission signal power for transmitting 1 bit of information increases, the transmission efficiency decreases, and when the transmission signal power for transmitting 1 bit of information decreases, the transmission efficiency increases.

  Further, in the second method, by increasing the redundancy of all error correction coding of a plurality of signals in the same manner, for example, the channel 2 having a larger SNR value compared to the SNR value a of the channel 1 originally. 3 has a problem that the SNR value is excessive with respect to the required SNR value, so that the transmission efficiency is reduced as the redundancy increases.

  SUMMARY OF THE INVENTION An object of the present invention made in view of such circumstances is a transmission device, a reception device, and a determination of the number of check bits that can realize video transmission satisfying a predetermined transmission quality and reducing errors without reducing transmission efficiency. It is to provide a method.

  In order to solve the above-described problem, a first transmission device according to the present invention is a transmission device that transmits an encoded signal that has been subjected to error correction coding by adding check bits to a plurality of channels of video signals. A common initial check bit number is set, a transmission quality indicator for each channel observed on the receiving side is obtained, and a check bit number determination unit that determines the check bit number obtained by increasing or decreasing the initial check bit number for each channel; An error correction encoding unit that outputs an encoded signal by adding an inspection bit of the number of inspection bits to the input video signal and outputs an encoded signal, and the inspection bit number determination unit includes: The worse the transmission quality indicated by the transmission quality indicator, the larger the number of inspection bits, and the total of all the inspection bits is equal to the product of the number of channels and the initial number of inspection bits. And determining the number of check bits as.

  In addition, the second transmission device according to the present invention maps the video signal of each channel so that the transmission rate after error correction coding of each channel is the same as that of the first transmission device. And the error correction coding unit performs error correction coding on the mapped video signal by adding check bits of the number of check bits for each channel, and outputs a coded signal. To do.

  A first receiving device according to the present invention is a receiving device that receives the encoded signal from the first transmitting device described above, receives the number of check bits, and determines each number of bits based on the number of check bits. An error correction decoding unit for correcting an error of the encoded signal of the channel is provided.

  A second receiving apparatus according to the present invention is a receiving apparatus that receives the encoded signal from the second transmitting apparatus described above, receives the number of check bits, and determines each check bit number based on the number of check bits. An error correction decoding unit that performs error correction on the encoded signal of a channel and outputs a decoded signal; and a demapping unit that demaps the decoded signal so that a transmission rate of the decoded signal of each channel is the same; It is characterized by providing.

  Also, the method for determining the number of check bits according to the present invention provides a check at the time of error correction coding for a transmitting apparatus that transmits a coded signal obtained by adding check bits to a video signal of a plurality of channels and performing error correction coding. A method for determining the number of bits for determining the number of bits, the step of setting an initial number of inspection bits common to all channels, the step of obtaining a transmission quality indicator for each channel observed on the receiving side, and the transmission quality The lower the transmission quality indicated by the index, the larger the number of inspection bits, and the initial number of inspection bits for each channel so that the sum of all the channels of the number of inspection bits is equal to the product of the number of channels and the number of initial inspection bits. Determining the number of check bits increased or decreased.

  According to the present invention, when the transmission quality index (SNR value, Q value, BER, MER, etc.) of the received signal is not uniform, the transmission efficiency is reduced by changing the redundancy of error correction coding. Therefore, it is possible to realize video transmission that satisfies predetermined transmission quality and has few errors.

It is a block diagram which shows schematic structure of the transmitter which concerns on the 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the error correction encoding part in the transmitter which concerns on the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the test bit number determination part in the transmitter which concerns on the 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the receiver which concerns on the 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the error correction decoding part in the receiver which concerns on the 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the transmitter which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the receiver which concerns on the 2nd Embodiment of this invention. It is a figure which shows the specific example of the error correction code | symbol of the transmitter which concerns on the 2nd Embodiment of this invention. It is a figure which shows the SNR vs. BER characteristic at the time of applying the redundancy of the BCH code shown in FIG. It is a figure which shows the WDM video signal transmission system using the conventional error correction code | symbol. It is a figure which shows the example of a SNR vs. BER characteristic. It is a figure which shows SNR after signal transmission. It is a flowchart which shows the determination method of the conventional test bit number.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a transmission apparatus according to the first embodiment of the present invention. In the example illustrated in FIG. 1, the transmission device 1 includes N error correction encoding units 11 (11-1 to 11 -N) and a check bit number determination unit 12. The transmission apparatus 1 receives a video signal divided into N channels (N signals) of channels 1 to N, performs error correction encoding, and transmits an encoded signal.

The error correction coding unit 11 inputs video signals having a transmission rate of xbps, performs error correction coding on the video signals, and outputs a signal having a transmission rate of y ₁ to y _N bps.

  FIG. 2 is a block diagram illustrating a configuration example of the error correction encoding unit 11. In the example illustrated in FIG. 2, the error correction encoding unit 11 includes a check bit adding unit 111 and an error encoding unit 112.

The inspection bit assignment unit 111 receives the number of inspection bits from the inspection bit number determination unit 12. For each n-k _i information bits, k _i check bits are calculated and added. Here, the subscript i means a channel number (1 ≦ i ≦ N).

The error encoding unit 112 outputs a signal error-encoded to n bits. In this case, the redundancy is k _i / n. When the number of check bits determined by the check bit number determination unit 12 is k ₁ bits for the error correction encoding unit 11-1,..., And k _N bits for the error correction encoding unit 11-N, The transmission rate can be expressed by equation (1).

The check bit number determination unit 12 acquires the transmission quality index for each channel observed on the receiving side, and sets the check bit number k _i to be given to the error correction coding unit 11 so that each channel satisfies a desired BER. decide. In general, when n is fixed, as the redundancy increases, that is, the number of check bits increases, the amount of improvement in BER in the case of error correction from the case of no error correction shown in FIG. 11 increases. Become. Hereinafter, for comparison, the conventional method for determining the number of check bits will be described, and then the method for determining the number of check bits according to the present invention will be described.

  FIG. 13 is a flowchart showing an operation example of a conventional method for determining the number of check bits. On the transmission side, an SNR value list for each channel (each wavelength) observed on the reception side is acquired (step S101). The acquisition method includes, for example, a method of feeding back the SNR value observed on the reception side to the transmission side using another line, and a method of notifying the transmission side from the reception side offline.

  Next, a required SNR value set in advance is acquired (step S102), and it is determined whether or not an SNR value smaller than the required SNR value exists in the acquired SNR value list (step S103). If at least one SNR value is smaller than the required SNR value (step S103-Yes), it is assumed that a bit error exceeding a predetermined BER occurs and video transmission with few errors becomes difficult. The configuration is changed (step S104). The configuration change is performed by, for example, the first method or the second method described above. However, the transmission efficiency is reduced by changing the configuration. After the configuration change, the process returns to step S101 again.

  On the other hand, when there is no SNR value smaller than the required SNR value (step S103-No), it is considered that video can be transmitted with a bit error rate equal to or lower than a predetermined BER. Further, the required SNR value varies depending on the type of error correction code and the number of check bits (redundancy). Therefore, the number of inspection bits k common to all channels is determined so that the required SNR values of all channels become the required SNR values acquired in step S102 (step S105).

  FIG. 3 is a flowchart showing an operation example of the check bit number determination method by the check bit number determination unit 12 according to the present invention. This process may be started before starting transmission, or may be started by monitoring and detecting deterioration of the transmission quality index during transmission. In addition, this process may be performed by the user instead of the check bit number determination unit 12, and the user may determine the number of check bits for error correction encoding and set the error correction encoding unit 11.

First, an initial check bit number k common to all channels is set (step S201). Then, on the transmission side, an SNR value list (SNR _i ) for each channel observed on the reception side is acquired (step S202). A transmission quality index other than the SNR value may be used. The transmission quality index acquisition method includes, for example, a method of feeding back a transmission quality index observed on the reception side to the transmission side using a separate line, and a method of notifying the transmission side from the reception side to the transmission side. Hereinafter, the number of check bits given to each error correction encoding unit 11 will be described as k _i .

Next, a desired BER value (tBER) set in advance is acquired (step S203), and k _i ^min is obtained from equation (2) (step S204).

Here, BER (SNR _i , k ′) means a bit error rate determined from the number of check bits k ′ in SNR _i . k _i ^min means the minimum number of check bits that can make the bit error rate smaller than the desired BER. If there is no k _i ^min among i = 1 to N (step S205—No), the desired BER cannot be achieved no matter how much the number of check bits k ′ is increased, and the configuration is changed (step S206). ). Incidentally, an upper limit is provided to the value of k _i ^min, may be performed configuration changes if k _i ^min exceeds the upper limit value.

On the other hand, if k _i ^min is present for all i = 1 to N (step S205—Yes), L _i is obtained from equation (3) for all i = 1 to N (step S207).

Here, L _i > 0 means that in channel i, the desired BER can be achieved even if the number of check bits is decreased by | L _i |. On the other hand, L _i <0 means that the desired BER can be achieved by increasing the number of check bits by | L _i |. Thus, _{L i} is determined whether or not satisfying the equation (4) (step S208), _{if L i} does not satisfy the formula (4) (step S208-No), performs the configuration changes (step S206) .

On the other hand, when Expression (4) is satisfied (step S208-Yes), the channel with the smaller SNR value (transmission quality index) in all channels with L _i > 0 and L _j <0 (where i ≠ j). The number of check bits is large and the condition of equation (5) is satisfied, that is, the sum of all the check bit numbers is the product of the number of channels N and the initial check bit number k. Check bits k _i obtained by increasing / decreasing the initial check bit number k for each channel are determined so as to be equal (step S209). This allows all channels to determine a combination of such k _i to achieve the desired BER.

Incidentally, to ensure more transmission margin in the entire system (i.e., as small as possible BER _(SNR i than the desired BER, _{k i)} to) in terms of _{k i} of Equation (6) is minimum A combination is desirable.

FIG. 4 is a block diagram showing a schematic configuration of the receiving apparatus according to the first embodiment of the present invention. In the example illustrated in FIG. 4, the reception device 2 includes N error correction decoding units 21 (21-1 to 21-N). The receiving device 2 receives N encoded signals of transmission rates y _{1 to} y _N bps input from the transmitting device 1 shown in FIG. Then, error detection and correction are performed based on the number of check bits k _i determined by the transmission apparatus 1, and N decoded signals having a transmission rate of xbps are output.

  FIG. 5 is a block diagram illustrating a configuration example of the error correction decoding unit 21. In the example illustrated in FIG. 5, the error correction decoding unit 21 includes an error bit calculation unit 211 and an error correction unit 212.

The error bit calculation unit 211 acquires the number of check bits k _i determined by the transmission device 1. The acquisition method includes a method of notifying from the transmission side to the reception side using a separate line, a method of notification offline, a method of superimposing on information bits, and the like. The error bit calculation unit 211 calculates an error bit using k _i check bits added to n−k _i information bits.

Error correction section 212 performs error correction coded signal, and outputs the error-corrected signal n-k _i bits to the input n bits.

  As described above, according to the present invention, when the transmission quality index (SNR value, Q value, BER, MER, etc.) of the received signal is not uniform, the redundancy of error correction coding is changed for each channel. Thus, it is possible to realize video transmission that satisfies predetermined transmission quality and has few errors without reducing transmission efficiency.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 6 is a block diagram showing a schematic configuration of a transmission apparatus according to the second embodiment of the present invention. In the example illustrated in FIG. 6, the transmission apparatus 3 includes N error correction encoding units 11 (11-1 to 11-N), a check bit number determination unit 12, and a mapping unit 13. The transmission device 3 of the second embodiment is different from the transmission device 1 of the first embodiment in that it further includes a mapping unit 13 and a method for determining the number of check bits by the check bit number determination unit 12. . Since other configurations are the same as those in the first embodiment, description thereof will be omitted as appropriate.

The mapping unit 13 acquires the number of check bits k _i of each channel from the check bit number determination unit 12 and N input signals (transmissions) so that the transmission rates output from the error correction coding unit 11 are the same. The transmission rate of the rate xpbs) is adjusted and mapped to a signal with a transmission rate of x ₁ to x _N bps. However, it shall satisfy | fill Formula (7).

When the number of check bits given by the error correction encoder 11 is k ₁ bits for the error correction encoder 11-1,..., And k _N bits for the error correction encoder 11-N, the error correction code The transmission rate of the signal input to the conversion unit 11 is expressed by Expression (8). Here, k is, for example, the number of check bits according to the conventional method described with reference to FIG. 13 (check bits when the smallest SNR value among the SNR values of a plurality of channels is designed to satisfy the required SNR value. Number).

  The error correction encoding unit 11 performs error correction encoding using the same type of error correction code as in the first embodiment, and the transmission rate of each output signal is y = n · x according to equation (1). / (N−k) is the same.

  FIG. 7 is a block diagram showing a schematic configuration of a receiving apparatus according to the second embodiment of the present invention. In the example illustrated in FIG. 7, the reception device 4 includes N error correction decoding units 21 (21-1 to 21 -N) and a demapping unit 22. The receiving device 4 of the second embodiment is different from the receiving device 2 of the first embodiment in that it further includes a demapping unit 22. Since other configurations are the same as those of the first embodiment, description thereof will be omitted as appropriate.

The receiving device 4 receives N encoded signals of the transmission rate ybps input from the transmitting device 3 shown in FIG. Then, error detection and correction are performed based on the number of check bits k _i determined by the transmission device 3, and N signals having a transmission rate of xbps are output.

The error correction decoding unit 21 acquires the number of check bits k _i determined by the transmission device 3. Then, error detection / correction is performed on the N encoded signals of the transmission rate ybps by using the k _i check bits added to the n−k _i information bits, and the transmission rate is x ₁ to x _N. N decoded signals of bps are output to the demapping unit 22.

The demapping unit 22 outputs N signals having a transmission rate of x bps by performing processing reverse to that of the mapping unit 13 of the transmission device 3. That is, the demapping unit 22 performs demapping by adjusting the transmission rate of the decoded signal so that the transmission rates x _{1 to} x _N bps of the decoded signal of each channel are the same (xpbs).

  In the first embodiment, the N encoded signals output from the transmission apparatus 1 have different code lengths and different operation clocks for E / O conversion and O / E conversion, but the mapping unit 13 and the demapping unit 22 are different. Can be omitted. On the other hand, in the second embodiment, by making the code lengths of the N encoded signals the same, the operation clocks of E / O conversion and O / E conversion can be made the same, and the hardware processing is simplified. Can be

  FIG. 8 is a diagram illustrating a specific example of the error correction code of the transmission apparatus according to the second embodiment of the present invention. FIG. 8A is a specific example of an error correction code in which the number of check bits is the number of initial check bits common between channels. BCH (2047, 1926) represents that the error correction code is a BCH code, the code length is 2047 bits, and the number of information bits is 1926 bits. In this example, the initial check bit number k = 121.

FIG. 8B is a specific example of an error correction code in which the number of check bits is adjusted. In this example, for the channels 1 and 2, the mapping unit 13 maps the transmission rate xbps signals to 0.96 xbps and 1.04 xbps signals. For each signal, BCH (2047, 1849) and BCH (2047) are mapped. , 2003), error correction coding with different redundancy is performed, and two signals having the same transmission rate of ybps are output. The number of check bits k ₁ = 198 and the number of check bits k ₂ = 44, and the total number of check bits is equal to the example of FIG.

FIG. 9 is a diagram showing SNR vs. BER characteristics when the redundancy of the BCH code shown in FIG. 8 is applied. As can be seen from the figure, in the present invention, when the required SNR is not constant and the desired BER is 10 ⁻⁷ , the channel 1 BCH (2047, 1849) and the channel 2 BCH (2047, 2003) There is a difference of about 2 dB. For example, when the SNR value is 15 dB for channel 1 and 17 dB for channel 2, in the conventional method, error correction code is performed using BCH (2047, 1849) in all channels, so transmission efficiency decreases. . If the number of check bits remains the initial value, channel 1 cannot satisfy the required SNR value of 15.6 dB of BCH (2047, 1926). On the other hand, according to the present invention, channel 1 can satisfy the required SNR value 14.8 dB of BCH (2047, 1849), and channel 2 can satisfy the required SNR value 16.9 dB of BCH (2047, 2003). Therefore, video transmission with a desired BER is possible without reducing transmission efficiency.

  Although the above embodiment has been described as a representative example, it will be apparent to those skilled in the art that many changes and substitutions can be made within the spirit and scope of the invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims. For example, a plurality of constituent blocks described in the embodiments can be combined into one, or one constituent block can be divided.

  In addition, a computer can be suitably used to function as the above-described transmission device 1, 3 or reception device 2, 4. This can be realized by storing a program describing the processing contents for realizing the function in a storage unit of the computer, and reading and executing the program by the CPU of the computer. This program can be recorded on a computer-readable recording medium.

  The present invention can be used, for example, in a video transmission system that transmits a target distance by multiplexing a plurality of optical signals constituting a large-capacity video signal. In FIG. 10, WDM is presented as a technique for multiplexing and transmitting a plurality of signals. However, the present invention can also be used in polarization multiplexing, spatial multiplexing using a plurality of fibers, multi-core fibers, and the like. is there.

DESCRIPTION OF SYMBOLS 1,3 Transmitter 2,4 Receiver 11 Correction encoding part 12 Check bit number determination part 13 Mapping 21 Error correction decoding part 22 Demapping part 111 Check bit provision part 112 Error encoding part 211 Error bit calculation part 212 Error correction Part

Claims (5)

A transmission device that transmits an encoded signal that has been subjected to error correction encoding by adding a check bit to a video signal of a plurality of channels,
Set the initial number of inspection bits common to all channels, obtain the transmission quality index for each channel observed on the receiving side, and determine the number of inspection bits by increasing or decreasing the number of initial inspection bits for each channel And
An error correction encoding unit that outputs an encoded signal by adding an error correction code to the input video signal by adding the check bits of the number of check bits for each channel; and
The inspection bit number determination unit increases the number of inspection bits as the transmission quality indicated by the transmission quality indicator is worse, and the sum of all the channels of the inspection bit number is equal to the product of the number of channels and the initial number of inspection bits. And determining the number of check bits. A mapping unit that maps the video signal of each channel so that the transmission rate after error correction coding of each channel is the same;
The error correction encoding unit performs error correction encoding on the mapped video signal by adding check bits of the number of check bits for each channel, and outputs an encoded signal. The transmitting device according to 1. A reception device that receives the encoded signal from the transmission device according to claim 1,
A receiving apparatus comprising: an error correction decoding unit that acquires the number of check bits and performs error correction on the encoded signal of each channel based on the number of check bits. A reception device that receives the encoded signal from the transmission device according to claim 2,
An error correction decoding unit that obtains the number of check bits, performs error correction on the encoded signal of each channel based on the number of check bits, and outputs a decoded signal;
A demapping unit for demapping the decoded signal so that the transmission rate of the decoded signal of each channel is the same;
A receiving apparatus comprising: A method of determining the number of check bits for determining the number of check bits when performing error correction coding for a transmission apparatus that transmits a coded signal that has been subjected to error correction coding by adding check bits to video signals of a plurality of channels. ,
Setting an initial number of inspection bits common to all channels;
Obtaining a transmission quality indicator for each channel observed on the receiving side;
The initial inspection for each channel is performed such that the lower the transmission quality indicated by the transmission quality indicator, the larger the number of inspection bits, and the sum of all the channels of the number of inspection bits equals the product of the number of channels and the number of initial inspection bits. Determining the number of test bits by increasing or decreasing the number of bits;
A method for determining the number of check bits.

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