JPH0136743B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to multi-level data transmission systems, and in particular to (1, 0, -1) type partial response systems (or class partial response systems), and particularly to codes for simultaneous transmission of secondary information in partial response transmission. Regarding the conversion method. Secondary information in the simultaneous transmission system as described above generally includes low-speed status information such as warnings, various game commands, and management information. When transmitting data using codes with such redundancy,
We have already discussed how to transmit the above secondary information by intentionally violating this encoding rule.
An example of transmitting control information using a violation in AMI (Alternate Mark Inversion) encoding is known. Now, the class partial response code is 2
Since the AMI codes of the series are interleaved, it is possible to transmit secondary information through the above violation. On the other hand, code errors during data transmission can be constantly monitored using the redundancy of class partial response codes, but this method uses a method to detect violations of coding rules caused by transmission errors. It will be done. Therefore, it has conventionally been thought that transmission of secondary information due to violation of encoding rules and monitoring of code errors are incompatible. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a system that enables transmission of secondary information while constantly monitoring code errors in class partial response code transmission. In order to achieve the above object, the present invention focuses on the fact that in the case of normal transmission path errors, when the error rate is not so large, two or more violations rarely occur in a row, By performing an operation that causes two consecutive violations, it is possible to simultaneously transmit secondary information and monitor code errors. According to the present invention, in the encoding system for class partial response code transmission, the transmitting side has a function of giving encoding rule violation to a predetermined bit pattern of the precoder, and the receiving side If a single violation is detected in the output of the detector, it is assumed to be a transmission line code error, and two consecutive violations are detected with one bit in between. This provides an encoding system characterized by having a function of determining that when a violation occurs, it is a violation operation performed on the transmitting side. Next, the present invention will be explained in detail with reference to the drawings. FIG. 1 is a diagram for explaining a class partial response code. In Figure 1, 4
is mod N adder (+), 5 is subtractor (Σ), 6
each represents a 1-symbol delay element (T). Then, the input N-ary code sequence a _o and the intermediate N
Between the base code sequence b _o and the output code sequence c _o , b _o = a _o + b _o-2 (+ is the addition of mod N)...(1) c _o = b _o −b _o-2 0 a _o , b _o N-1. FIG. 2 is a diagram for explaining violation detection in the receiving section. In FIG. 2, 7 is an adder, 8 is a modulo-N discriminator, and 9 is a violation detector. This violation detector outputs 1 as the output v _o when it detects a violation, and outputs 1 as the output v _o when it does not detect a violation.
It has a function of outputting 0 as 0, but it also has a function of correcting the cumulative sum s _o of the received signal C _o according to an algorithm. Input c _o ' indicates that output c _o of FIG. 1 has been erroneously transmitted. This c _o ′ is decoded by the modulo-N discriminator 8 as a o ′ as a _o ′=c _o ′ (2 ₎ . On the other hand, the cumulative sum s _o is expressed as s _o = s ^* _o-2 + c _o ′...(3). Here, s _o ^* , which is the output of the violation detector 9, is determined as follows. (i) If S _o N, violation is detected S _o
^* =N-1. (ii) If S _o −1, violation is detected.
Let S _o ^* =0. (iii) Others are considered to be non-violation detection S _o ^*
=S _o . Now, in the case of normal transmission path errors, if the error rate is not so large, most errors occur randomly and occur at adjacent levels. In other words, it can be said that there are almost no cases where _vo becomes 1 for two or more consecutive times. The meaning of "two in a row" here is that the class partial response code is essentially an interleaving of two sequences, so v _o = 1 and v _{o +2} = 1 occur. be. Focusing on the above points, the present invention intentionally adds a characteristic violation in the transmitting section so that the violation detector in the receiving section detects two violations in a row. , it is possible to transmit secondary information while monitoring single code errors on the transmission path. The characteristic point of the present invention is that the encoder
For example, a violation operation (hereinafter referred to as VIOL) that inverts the polarity of the output c _{o -4} when B _o-6 b _o-4 b _o-2 b _o It is called "operation". Note that X is the other interleaved series and is not related to the above VIOL operation of series b _o . The output obtained by applying the VIOL operation (in this case, subtracting N = 4) to c _o-4 of the output series c _o is c _o ^*
If Y is (b _o-6 − _{b o-8} ), c _o and the output c _o ^* after the operation correspond to the above series b _o , a _o : ZX2X2X0 ZX2X1X0 b _o : 0X2X0X0 1X3X0X0 c _o :YX2X−2X0 YX2X−3X0 ↓VIOL operation ↓VIOL operation c _o ^* :YX−2X−2X0 YX−2X−3X0 d _o :ZX2X2X0 ZX2X1X0 When a violation occurs in this way, the sign of d _o due to this No error occurs, and the violation detector (9 in Figure 2) that uses cumulative sum as described above detects two violations in a row. In other words, it becomes possible to transmit low-speed secondary information. In addition, in the above example, when comparing the cumulative sum of C _o and the cumulative sum of C _o ^* , in the case of the cumulative sum of C _o ^* , it is determined that "two digits in a row"
Indicates that a violation is detected. C _o YY2X−2X0 YX2X−3X0 S _o 0X2X0X0 1X3X0X0 V _o 0X0X0X0 0X0X0X0 C _o ^* YX−2X−2X0 YX−2X−3X0 S _o 0X−2X−2X0 1X−1X−3X0 S _o ^* 0X0X0X0 1X0X0X0 V _o 0X1X1 X0 0X1X1X0 In this way, in the transmitting section, when the above-described 0X2X0X0 or 1X3X0X0... appears as the b _o series, an operation may be performed to intentionally add a violation to reverse the polarity of C _o-4 . Furthermore, if the transmission code {a _o } is randomized, such a sequence of b _o will occur with a certain probability. Note that when the error in the S _o sequence is corrected by the circuit 9, S _o matches the same sequence over time as it would have been without the VIOL operation. This means that
The following S _o and S _o when 0X2X0X0 as the series of b _o
It is clear from the series. In addition, each symbol a _o ~
All S _o are initialized to 0.

[Table] Other such b _o series include 3X1X3X3
Or there is 2X0X3X3.

[Table] In this case, it is a violation operation that changes 2 to -2 and -2 to 2 on series c _o . There are other violation operations such as 3→-1, 1→-3, -1→3, and -3→1.
Table 1 summarizes the series b _o , the series c _o after the violation operation, and the series s _o . In Table 1, the first S _o series is determined by a trial-and-error method to ensure that when a running sum is taken, a value of +3 or more does not appear and a violation is not detected.

[Table] As described above, in the multilevel partial response coding method, when a specific b _o occurs, one symbol of the output sequence is changed modulo N, and the violation detector in the receiver By characteristically detecting two consecutive violations, it becomes possible to simultaneously transmit status signals and the like without code errors. FIG. 3 shows the configuration of the transmitter of the present invention. In the figure, the transmitting section is composed of a conventional multilevel class partial response encoder 10 and a violation generator 20. Reference number 1
1, 13, and 14 are a multilevel transmission code, a transmission line transmission code, and sub information, respectively. FIG. 4 shows the configuration of the receiving section of the present invention. In the figure, the receiving section is a main data signal output consisting of a conventional violation detector 30, two consecutive violation discriminators 40, and a modulo-N decoder 50. Furthermore, in the present invention, by classifying the successive violation patterns in the sequence _so (see Table 1) into several types, it is possible to distinguish and transmit various types of sub-information.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams for explaining a multi-level class partial response encoding method, and FIGS. 3 and 4 are block diagrams of a transmitting section and a receiving section for explaining an embodiment of the present invention. . In FIGS. 3 and 4, 10...partial response encoder, 20
...Violation generator, 30...Violation detector, 40...Discriminator.

Claims (1)

[Claims] 1 a first adder that calculates modulo N of the N symbols when N is an integer of 3 or more, and a first delay circuit that delays the output of the first adder by two symbol times. , means for supplying the output of the first delay circuit to the first adder, and a subtracter for determining the difference between the output of the first adder and the output of the first delay circuit. a second adder for adding the received signal from the transmitter and the sum signal; and an output of the second adder when the output of the second adder is greater than N or negative. A violation detector that outputs a signal indicating the presence of violation while correcting it to N-1 or 0, respectively, and a second delay circuit that delays the output of this detector by two symbols and outputs it as the cumulative sum signal. In a 1, 0, -1 type partial response encoding system having a receiving section including When a specific pattern appears, a violation operation is performed to violate the encoding rule once by changing the value of a symbol at a specific position of the specific pattern to a predetermined value, and in the receiving section,
The detector detects two violations in succession.
An encoding method characterized in that when a violation is detected, it is determined that a violation has occurred on the transmitting side.