JPH0129459B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a line identification system having a function of distinguishing between own line and other lines in a digital signal transmission system in which a plurality of lines exist.

Generally, in a digital signal transmission system, when there are multiple lines of the same system and the amount of interference between each line is large, for example, there is interference from a branch line, or there is interference from a station ahead of the opposing station. If there is interference caused by adjacent waves in different polarization bands when there are multiple lines in the same direction, even if the output power of the opposing transmitter is cut off, the receiver Since signals from other interfering lines are received, a situation arises in which a line failure of the own line cannot be detected. There is a line identification method for identifying one's own line from other lines when such mutual interference exists between lines.

As a conventional line identification system, there is one that uses a line identification code, as shown in the block diagrams of the transmitting side and receiving side in FIGS. 1a and 1b. In the figure,
1 and 1' are frame synchronization code generation circuits that synchronize data signals, 2 and 2' are line identification code generation circuits that are added to data signals, and 3 and 3' are scrambling code generation circuits, which are connected to the transmission system and The same circuit can be used for the receiving system. 4 is a counter circuit that counts the same clock as the data signal and outputs the frame head signal; 5, 6, 7, 10;
Reference numeral 8 indicates a synthesis circuit that adds data signals using an adder or an exclusive OR circuit, 8 a comparison circuit, and 9 a frame synchronization circuit that detects frame synchronization. In this method, in the transmitter, a frame synchronization signal from a frame synchronization signal generation circuit 1 and a line identification bit from a line identification code generation circuit 2 are added to a data signal by synthesis circuits 5 and 6.
Further, the pseudo-random code generated from the scramble code generation circuit 3 is added to the signal scrambled by the synthesis circuit 7 and transmitted, and the pseudo-random code generated by the scramble code generation circuit 3' is transmitted to the synthesis circuit 10 in the receiving device. In addition, the data signal is descrambled to detect the line identification bit in the data signal, and the line identification code generation circuit 2' of the receiving device
A method has been considered in which the comparison circuit 8 compares the line identification code generated by the line identification code to determine whether the line is the own line or another line.

Furthermore, FIGS. 2a and 2b are block diagrams of systems in which frame synchronization codes are different. This method uses the first
The principle is the same as the system shown in the figure, but instead of having the line identification code generation circuits 2 and 2', feedback circuits 11 and 11' are added to the frame synchronization code generation circuits 1 and 1' of both transmitting and receiving devices, and frame synchronization code generation circuits 11 and 11' are added. This method obtains line identification information by preparing multiple .

However, in these conventional methods, the system shown in FIG. 1 requires line identification code generation circuits 2 and 2' consisting of complicated circuits for the line identification function.
This has resulted in the disadvantage that this circuit often tends to be large-scale. Furthermore, in the system shown in FIG. 2, in order to identify the line, it is necessary to use different combinations of frame synchronization codes for the own line and other lines. These frame synchronization code generation circuits 1, 1' are as follows:
Generally, a feedback shift register (hereinafter referred to as
FSR), but for line identification, feedback circuits 11 and 11' are used.
Since the method of FSR feedback must be different between the own line and other lines, in order to increase the number of identified lines, these feedback circuits 11 and 11' become more complex and larger in scale. It was hot.

SUMMARY OF THE INVENTION An object of the present invention is to solve these drawbacks and provide a line identification system that is simple, compact, and composed of small-scale circuits.

The configuration of the present invention is that, on the transmitting side, an input data signal is scrambled using a scrambling code consisting of a pseudo-random signal with a period of one frame and transmitted, and on the receiving side, the input data signal is descrambled using the same scrambling code as the scrambling code. In a code communication line identification system for reproducing an input data signal, a code shifting means is provided for shifting each of the scrambling codes by a predetermined shift amount, and the shift amount is set to be different between the own line and other lines. The feature is that these lines can be distinguished from other lines by doing so.

The present invention will be explained in detail below with reference to the drawings.

3a and 3b are block diagrams of the transmitter and receiver sides of an embodiment of the present invention. In the figure, the same numbers as in FIG. 1 indicate the same components, 20,
20' indicates a shift register circuit.

In this type of transmitter/receiver, a short periodic input signal is generally converted into a long period code in order to facilitate the clock extraction of the receiver, smooth the transmission spectrum, and average the mark rate of the output signal of the transmitter. There is a scrambling function for converting into a sequence, and the scrambling code sequence used for this is composed of pseudo-random codes. Since this scrambled code string has a long period and little correlation, the code string obtained by periodically sampling the scrambled code is shifted n bits (n is the number of scrambling bits for one frame period from 1) at the same period and is then sampled. The probability of matching the column is very small.

In the present invention, focusing on this point, the line identification bits are scrambled by the transmitting device and descrambled by the receiving device by changing the shift amount between the own line and the other line. It is characterized by the following.

That is, as shown in FIGS. 3a and 3b, the line identification bit string in the transmitter includes a fixed code string,
For example, using the frame synchronization code generated by the frame synchronization code generation circuit 1, the scramble code generated by the scramble code generation circuit 3 is n
The data is shifted and scrambled by the shift register circuit 20 of the stage and then transmitted. In addition, in the receiving device, a scramble code whose pattern is phase-synchronized on the frame is output by the scramble code generation circuit 3' according to the frame head signal output from the frame synchronization circuit 9, and the scramble code is outputted from the n-stage shift register circuit 20. ' to descramble the received signal. The line identification bit string in this descrambled signal is compared with the frame synchronization signal outputted from the frame synchronization code generation circuit 1' in the comparator circuit 8. Since these frame synchronization codes are the same in both the transmitting and receiving devices, when the receiving device receives the signal of its own line, the comparison result will be a match, and it will be determined that it is the own line.

On the other hand, on other lines, both the transmitter and receiver
The number of stages n' of the shift register circuits 20, 20'(n' is n
If the number of scrambling bits is 1 to one period of a frame), the scrambled line identification bit string in the output signal of the transmitter is different from that of the own line. Therefore, when the receiving device of the own line receives a signal of another line, the signal is descrambled using a scramble code shifted by n bits, so the line identification bit string does not match the frame synchronization code, so the comparison circuit 8 It is determined that it is a line. Further, since the signal input to the frame synchronization circuit 9 is different from the frame synchronization code generated on the receiving device side, synchronization is lost, and therefore it is determined that the line is another line.

As explained above, according to the present invention, the line identification function is realized by a simple and small-scale circuit called a shift register, and even when the number of identified lines is increased, the number of stages of the shift register can be increased. This can be achieved by using only one method, and the effect is great when applied to digital lines.

[Brief explanation of drawings]

Figures 1a and b are block diagrams of the sending and receiving sides of a line identification system with a conventional line identification code generation circuit, and Figures 2a and b are block diagrams of a line identification system that changes the frame synchronization code using a conventional feedback circuit. Block diagram of the transmitting and receiving sides of FIG. 3a,
b is a block diagram of the transmitting side and receiving side of an embodiment of the present invention. In the figure, 1, 1'...frame synchronization code generation circuit, 2, 2'...line identification code generation circuit, 3,
3'... Scramble code generation circuit, 4... Counter circuit, 5, 6, 7, 10... Synthesizing circuit, 8...
... Comparison circuit, 9 ... Frame synchronization circuit, 11, 1
1'...feedback circuit, 20, 20'...shift register circuit.

Claims (1)

[Claims] 1. On the transmitting side, the input data signal is scrambled with a scrambling code consisting of a pseudo-random signal with a period of one frame and transmitted, and on the receiving side, the input data signal is descrambled with a scrambling code similar to the scrambling code. In the line identification system for code communication to be reproduced, code shifting means for shifting each of the scramble codes by a predetermined shift amount is provided, and the shift amounts are set to be different between the local line and other lines. A line identification method that distinguishes between the own line and other lines.