JPH01109826A - Code conversion system - Google Patents

Abstract

PURPOSE:To attain the code conversion with a stable mark and a comparatively low cost by providing two sets of coded n-bit patterns corresponding to an inputted m-bit pattern, and switching them at a prescribed period being an integral number of multiple of n-bit. CONSTITUTION:A 4-bit input data 108 sent from a host circuit is converted into a 5-bit data by a code rule ROM 106, and sampled at the rise of a sampling signal 103 by a register 107. A counter 102 is counted up at the rise of the sampling signal 103 by the counter 102 and a data of the register 107 is inverted by an inversion circuit 104 when the counter 102 counts up logical '1' and a coded signal 109 is supplied to a frame generating circuit 11. A selection circuit 110 sends the coded signal 109 to a transmission line 30 as a data signal 300 when a command signal 101 is not fed. The output of the code rule ROM 106 has a mark rate of 0.4 and the in-frame information has in average a mark rate of 0.5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a code conversion system, and particularly to an MBNB code conversion system suitable for high-speed data transmission.

[Conventional technology]

Conventionally, many transmission path codes for binary signals used for data transmission have been considered. Typical examples include Manchester code and country! There is a sign.

These codes convert 1 bit of data to be transmitted into 2 bits, and are excellent in terms of constant mark rate and ease of timing extraction.

However, on the other hand, it required a transmission line frequency twice the data transfer frequency. For this reason, in recent years, with the emergence of a need for high-speed data transmission, a method has been developed to convert the transmission line frequency and data rate into one bit.
Publication No. 05+51 "Code transmission method" is mentioned.

According to this system, the ratio of the data transmission station wave number to the transmission path/frequency is only m to 1, so that more efficient transmission can be performed than with conventional codes. Another advantage of this method is that the transmission line frequency can be kept relatively low, which is required for the transmission circuit. There are times when costs can be lowered.

[Problem that the invention seeks to solve]

However, there was also the problem that as the ratio of books to book became smaller and the temperature increased, the mark rate could no longer be kept constant. For example, 8j510h using the typical mhnb system
For example, there are 10 possible patterns of 70 bits.
Among the 24 patterns, there are only 254 patterns with mark rates O and S. Considering timing extraction, the number of usable patterns will further decrease. Therefore, a mark rate of 0.5 cannot be guaranteed for some patterns among the 256 patterns that an 8-bit bit string can take.

An object of the present invention is to provide an mbnb code conversion method that eliminates such problems and provides a stable mark rate.

[Means for solving problems]

In order to achieve the above object, in the present invention, conventional mbnA
Unlike the code conversion method, two sets of encoded rubit patterns corresponding to the input m-bit pattern are provided, and these two sets of patterns are mutually inverted and each bit is inverted. It is also assumed that which of these two patterns is used is switched at a constant cycle of an integer multiple of 1 or m bits. As a result, for example, if the mark rate of the pattern is (0,5 + ,5+X) + (0,5-x)
/ 2 = o, s.

[Effect]

According to the present invention, when encoding consecutive number turns of a particular door bit, the output of the transcoder circuit outputs only one kind of number turns according to a certain encoding rule, but the same pattern When sequentially encoding , the output turn of the conversion circuit is reversed, so as a result, for a given m-bit input turn, two logically exclusive rubit patterns are created in the previous code. It will be made into

〔Example〕

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 8 shows a transmission system using the present invention.

Transmission data generated in the transmission device f1 is encoded by the encoding circuit 102 in the transmission device 1, and sent to the transmission device f2 using the frame generation circuit 11 in the format shown in FIG. In FIG. 9, D is a delimiter indicating the end of the beginning of 7 frames. The frame that is closer than the transmission device 1 is transmitted through the transmission path 50.
The data received by the transmission device @2 shown in FIG.
It is decoded by

FIG. 1 shows the circuit configurations of the encoding circuit 10 and the frame generation circuit 11. The operation of the circuit shown in FIG. 1 will be explained below with reference to the time chart shown in FIG. Delimiter sending instruction signal 10 issued from the upper circuit (not shown)
1, the 1-bit counter 102 is set, and at the same time, the selection circuit 110 in the frame generation circuit 11 sends out the delimiter generated by the pattern generator 112vc to the transmission path 50.

The 4-bit input data 108' sent from the upper circuit is converted into 5-bit data by the code rule filter 106 according to the conversion rule shown in FIG. 5, and sampled in the register 107 at the rising edge of the sampling signal 105. The color/return signal 102 is counted up at the rising edge of the sampling signal 105, and when 102 is the logical value 1", the inversion 00M1o4 inverts the data in the register 107 and provides the encoded signal 109 to the frame generation circuit 11. 110 sends the encoded signal 109 as a data signal 500 to the transmission path 50 when the instruction signal 101 is not raised.When this circuit is used to transmit a series of data as shown in FIG. The output of the code rule ROM 106 has a mark rate of 0.4, as shown in FIG. 5, but the intra-frame information has an average of C1.5Vc.

Although the above description has been made regarding the encoding circuit, the circuit configuration regarding the decoding circuit 20 and the frame detection circuit 21 is shown in FIG. The explanation will be given below according to the time chart shown in FIG.

Delimiter pattern generator 214 input from transmission line 30
Based on this, the delimiter detection circuit 210 detects and outputs a delimiter detection signal 211. A counter 202 is set by the delimiter detection signal 211. The output clock signal 215 of the circuit 212 that extracts the clock from the information input from the transmission line 50 causes the 1-bit counter 202 to
is counted up. When the counter 202 has a logical value @1'', the data signal 500 from the transmission path 50 is inverted by the inverting circuit 204K and provides input data 207 to the ROM 206.Decoding 11) The ROM receives 5-bit input data. 207 outputs 4-bit 0 output data 208 using the conversion rule shown in Figure 5. This is how decoding is performed. Although the configuration is such that inversion is repeated, generally the capacity of the counter 102 and 202 is set to R bits, and by detecting a specific bit of the counter, encoded data can be inverted at a period C that is an integer multiple of rubits.

Note that the delimiter in the above description is a specific pattern that does not match the 5-bit pattern shown in FIG. Regarding the code rule and the circuit on the decoding side, a ROM is used in this embodiment, but a logic circuit as shown in Japanese Patent Application Laid-Open No. 59-200561 "Code Transmission System" may also be used. Also group 5iI! Although the embodiment is explained using 4b5b as an example, it can be easily applied to other WLbnb by removing the code rule, changing the decoding rule register, and making the signal line a bit width suitable for the encoding method.

〔Effect of the invention〕

According to the present invention, stable mark rate code conversion can be performed at a relatively low cost for high-speed data transmission.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an encoding circuit according to an embodiment of the present invention, FIG. 2 is a time chart showing the operation of the circuit shown in FIG. 1, and FIG.
4 is a diagram illustrating code conversion rules, FIG. 4 is a diagram illustrating data before encoding, FIG. 5 is a diagram illustrating encoded data by frame structure, and FIG. 6 is an example of the present invention. 7 is a diagram showing the decoding circuit of FIG. 6, and FIG. 7 is a diagram showing the operation of the circuit shown in FIG. Ru. 10... Encoding circuit, 11... Frame generation circuit,
20.-Decoding circuit, 21.-Frame detection circuit, 10
2... Counter, 104... Inverting circuit, 106...
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Claims (1)

[Claims] 1. In a code conversion method in which m-bit data is converted into n-bit code data according to a predetermined encoding rule and then transmitted, the code-converted data is inverted at a cycle that is an integral multiple of n bits and then transmitted. A code conversion method characterized by: