JPS63109612A - mBnB decoder data conversion method - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a data conversion method for an mBnB decoder, and in particular uses mBnB codes as a code format on a transmission path between a transmitting terminal station and a receiving terminal station. Used for things that are used.

[Conventional technology]

The so-called mB is used as a code format in the transmission path between terminal stations.
The nB coding system is known. In this method, an m-bit (m is a positive integer) digital signal on the transmitting side is converted into an n-bit (n is a positive integer where m<n) digital signal and transmitted. It converts an n-bit signal into an m-bit signal.

FIG. 2 is a block diagram of an example of a data transmission system using a conventional method, in which a 586B code is used as a code format for a transmission path. As shown in the figure, the transmitting terminal station 1 and the transmitting terminal station 2 are connected by a transmission line 3. 5 (=m
>bit transmission data is input to the serial/parallel (S/P) converter 4 as an information code string of f [b/S]. The 5-bit parallel signal subjected to serial/parallel conversion by the S/P converter 4 is input to a 586B encoder 5, which is constituted by, for example, a ROM.

The 5-bit parallel signal input to the 586B encoder 5 is converted into a 6-bit parallel signal according to the preset 586B encoding rule, and is converted into a 6-bit parallel signal in parallel/serial (P/
S) Input to converter 6.

The 6-bit serial signal converted from parallel to serial by this P/S converter 6 is 615·f [b/s]
is sent to the transmission path 3 as an information code string. At this time, S
The clock of f[H4F is input to the /P converter 4, and the P
/S converter 6 receives 615·f[ through 615 multiplier 7
Since the H4F clock is input, the sending terminal station 1
In this case, 586B code conversion is performed for each piece of transmission data, and the data is sequentially sent to the receiving side terminal station 2 via the transmission line 3.

The timing (Tin) extraction circuit 8 of the receiving side terminal station 2 is as follows:
A clock of 615·f [Hz] is recovered from the received data of 615·f [b/S] sent via the transmission line 3, and this is given to the S/P converter 9, and the 5/6 multiplier circuit 1
0 to the P/S converter 11 as a clock of f[1-1z]. The S/P converter 9 is 615·f[b/s
] is subjected to serial/parallel conversion and provided to the 586B decoder 12 as a 6-bit parallel signal. 58
The 6B decoder 12 is composed of, for example, a ROM, and converts a 6-bit parallel signal into a 5-bit parallel signal according to a preset 586B decoding rule.

The P/S converter 11 performs parallel/serial conversion on this 5-bit parallel signal and outputs it as an information code string of f[b/sl. Here, as mentioned above, the S/P converter 9 has 61
5.f[H4F clock is input, P/S converter 1
Since the f[H4F clock is input to the receiving terminal station 2, the receiving terminal station 2 performs 586B decoding conversion for each piece of received data and reproduces the original signal.

As mentioned above, the reason why a 5-bit code string is converted into a 6-bit code string and transmitted can be explained as follows. In other words, a 5-bit code string can represent 2" = 32 types of data, including, for example, "o o o o o"
However, when the data of the code string "o o o o o" is continuously sent on the transmission line 3, the signal level on the transmission line 3 becomes "OtP".
The levels indicating the bits will be continuous. In this case, the signal level of the transmission line 3 becomes a DC level, making it impossible to ensure an appropriate duty ratio, and making transmission errors more likely to occur. So, convert it to 6 bits and use 26 bits.
By making it possible to send = 64 types of code strings, for example, 5 bits "o o o o o" can be converted to 6 bits "110010" and transmitted, and for example 5 bits "11 'l 11" ” is a 6-bit ’“001
If the signal is converted to 101" and transmitted, a duty ratio of a certain level or higher can be ensured at the signal level of the transmission line 3.

[Problem that the invention seeks to solve]

However, in the above conventional method, the received 6-bit code string is expanded in 6-bit parallel, and then 586B
Since a 5-bit code string is obtained by decoding and conversion, if there is a 1-bit error in transmission path 3, a 58-bit code string will be generated on the receiving side.
It can be seen that an error due to violation of the 6B coding rule appears.

This situation will be explained specifically. Now, the 5-bit parallel signal “11111” at the transmitting terminal station 1 is 586B.
The code is converted and the 6-bit serial signal “001101
" is sent to the receiving terminal station 2. At this time, a 1-bit transmission error occurs on the transmission line 3, and the receiving terminal station 2 transmits a 6-bit serial signal ""0O11'1.
1", the 5-bit parallel signal obtained by 586B decoding conversion is "o o o o
o”.The reason is that the 6-bit “001
111'' is a parallel signal that violates the 586B coding rule.

FIG. 4 is an explanation of this 586B code rule, where (a) shows a code that conforms to this code rule, and (b) shows a code that violates this code rule.

In the above example, a 1-bit transmission error causes a 5-bit burst error, but the present invention is not limited to this. That is, as shown in FIG. 4, for example, when a 1-bit transmission error occurs in 6-bit data "'011100" and it becomes "111100", the 5-bit data reproduced as a violation of the 586B coding rule is "o o o o o", which is 5 bit data "11100" obtained by converting error-free 6 bit data "011100" to 586B code.
Only 3 out of 5 bits are wrong.

Further, a 1-bit transmission error does not always result in a violation of the 586B coding rule, but may result in a result that conforms to the 586B coding rule.

However, as shown in FIG. 4, there are 18 out of 64 cases in which the 586B coding rule is violated in a 6-bit parallel signal, and in the worst case, a burst error occurs in all 5 bits. Such problems are caused by 586B
The same problem occurs not only with code formats but also with m3nB code formats in general.

Therefore, in the present invention, mBnB is
An object of the present invention is to provide a data conversion method for an mBnB decoder that does not cause m-bit burst errors even when an n-bit parallel signal that violates a coding rule appears.

[Means for solving problems]

The data conversion method of the mBnB encoder according to the present invention is mBnB
When the n-bit data input to the nB decoder violates the coding rule, it is assumed that a transmission path error has occurred for any one bit of this n-bit data, and mBnB
The present invention is characterized in that the above-mentioned n-bit data is converted into m-bit data set in advance so that the number of error bits in the m-bit data when decoded is probabilistically minimized.

[Effect]

Since the data conversion method of the mBnB decoder according to the present invention is configured as described above, when the n-bit data input to the mBnB decoder violates the coding rule, the n
The bit data is m such that the number of error bits is minimized with probability
Converted to bit data.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals and redundant description will be omitted.

FIG. 1 is a block diagram of a data transmission system using an embodiment of the method of the present invention.
B 68" code is used. And this is the third
The difference from the conventional example shown in the figure is that the 586B decoder 20 of the receiving terminal station 2 converts the 6-bit parallel signal that violates the coding rule into a predetermined 5-bit parallel signal.
It has a function of converting into a bit parallel signal and is equipped with a coding rule violation detection line 21. That is, the 586B decoder 20 stores the 5-bit data after decoding and conversion even for the 6-bit parallel signal that violates the coding rule. This 5-bit data, assuming that there is an error of 1 pin 1- in the 6-bit parallel signal,
The number of error bits in the 5-bit parallel signal after decoding and conversion is minimized in terms of probability.

FIG. 3 shows an example of the 586B decoding rule according to this embodiment. The "X pt" mark in the column indicated by code A in the figure is 586B.
The code rule is violated, and the column indicated by symbol B is the code rule violation detection bit output from line 21 in FIG. That is, when this bit is "1", it indicates that the coding rule is violated, and when it is "0", it indicates that the coding rule is met (not violated).

A detailed explanation will be given below according to this chart. Now, at the transmitting terminal station 1, the 5-bit parallel signal “11111” is
868 code conversion and 6-bit parallel signal "0011"
Suppose that a 1-bit error occurs on the transmission path 3 when the signal is transmitted as "01", and the 6-bit parallel signal at the receiving terminal station 2 becomes "001111", which violates the coding rule. In this case, the receiving terminal 2 can recognize that an error bit has occurred on the transmission path 3 because the received data violates the coding rule. It is impossible to recognize whether an error has occurred.

By the way, since the probability that an error will occur in a bit in the transmission path 3 is about 10-9, the occurrence of an error in two or more bits can be ignored. Therefore, it can be assumed that only a 1-bit error has occurred in the transmission line 3. Then, the original 6-bit parallel signal, which becomes "001111" due to a 1-bit error, is considered to be one of the following.

■001110 ■001101 ■001011 ■000111 ■01111 '1 ■101111 However, as is clear from FIG. 6-bit parallel signal “0”
01111'' can be said to be an error in any one of the above-mentioned errors.When the 6-bit parallel signals of above-mentioned 1-2 are subjected to 586B decoding conversion, the following is obtained as is clear from FIG.

■001110→01111 ■001101→11111 ■001011→01011 ■000111→00111 Therefore, when a 6-bit parallel signal “001111” that violates the <586B coding rule is received as shown in Figure 3,
The 586B decoder 20 in FIG. 1 is set to decode and convert this into a 5-bit parallel signal of "'01111". With this setting, there will be no error bit in the case of the above error pattern (2), and there will be only one error bit in the case of the above error patterns (2) to (2).

As explained above, if the 586B code (return) rule set in the 5B68 decoder 20 of FIG. 1 is set as shown in FIG. Even if it occurs, this 1-bit error will not cause a burst-like bit error in the 5-bit parallel signal after decoding and conversion. In particular, in the example shown in Figure 3, the error after decoding to 5 bits can be suppressed to 3 bits at most, and the probability that a 3-bit error will occur in 586B decoding for a 1-bit transmission path error is 0. This can be suppressed to about .5%, and therefore most errors can be up to 2 bits. In general, as in the case (2) above, there is a high possibility that there will be no error bits.

The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, it is applicable not only to 5B6-8 code formats but also to mBnB code formats in general. Also, set the sign rules, especially 6 (=
The method of decoding and converting the n>bit parallel signal into a 5 (=m>bit parallel signal) is not limited to the one shown in Fig. 3, but can be done in various ways.
When it is detected that the n-bit data input to the nB decoder violates the mBnB coding rule, any one of the n-bit data is
Assuming that errors occur in bits, any value of m-bit data is set so that the probability that an error bit will appear in m-bit data when mBnB decoding is performed is minimized. You can leave.

(Effects of the Invention) As described above in detail, according to the present invention, when the n-bit data input to the m3nB decoder violates the coding rule, the n-bit data is Since the conversion is made to the minimum m-bit data, even if an error bit appears in the n-bit data due to a transmission path error, if this corresponds to a violation of the coding rule, the burst shape of the m-bits in the m-bit data will be changed. This has the effect of minimizing the number of error bits without causing errors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an example of a data transmission system to which a first embodiment of the method of the present invention is applied; FIG. 2 is a block diagram showing the configuration of an example of a data transmission system to which the conventional method is applied; Figure 3 shows the 58 according to the embodiment shown in Figure 1.
FIG. 4 is an explanatory diagram of an example of the 6B decoding rule. FIG. 4 is an explanatory diagram of an example of the 586B coding rule. DESCRIPTION OF SYMBOLS 1... Sending side terminal station, 2... Receiving side terminal station, 3... Transmission line, 7... 615 multiplier, 8... Timing extraction circuit, 10... 5/6 multiplier , 21... Code rule violation detection line. Patent applicant: Sumitomo Electric Industries, Ltd. Representative Patent Attorney Yoshiki Hase Figure 3 (a) Figure 3 (D) Figure 4 (a)

Claims (1)

[Claims] 1. An mBnB decoder that uses an mBnB code (m, n are positive integers and m<n) as a transmission code format, and the input n
In the data conversion method of the mBnB decoder that converts bit data into m-bit data according to the mBnB coding rule, if the input n-bit data violates the coding rule, any one bit of this n-bit data is transmitted. Assuming that a path error has occurred, the m-bit data is set in advance so that the number of error bits in the m-bit data when mBnB decoded is probabilistically minimized.
mBn characterized in that the n-bit data is converted.
B decoder data conversion method. 2. The data conversion system for an mBnB decoder according to claim 1, wherein the n-bit data is a 6-bit parallel signal, and the m-bit data is a 5-bit parallel signal.