JPH0923216A - Line monitor system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase in the hardware by detecting the coincidence between a transmission digital signal sent via an active line and a transmission digital signal sent via a standby line so as to eliminate the need for a generating circuit and a reception circuit for a pilot signal. SOLUTION: A transmission digital signal is supplied from an input 101 and distributed into two by a distribution circuit 102. One distributed signal is given to a transmission code conversion circuit 105, in which the code is converted and a frame synchronizing signal is added to the converted code by a transmission signal processing circuit 106. Then the resulting signal is sent to a radio block transmission line 108 via a modulation circuit 107. The signal is regenerated by a demodulation circuit 109 at a receiver side, a frame synchronizing signal is separated in a reception signal processing circuit 110 and outputted to a changeover circuit 111. The output of the reception signal processing circuit 110 via an active circuit 1 and the output of a reception signal processing circuit 10 via a standby line 3 are compared in the changeover circuit 111. Then the result of comparison is sent to a terminal 1114 and either of the active and standby signals is selected and outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line monitoring system, and more particularly to a line monitoring system in a wireless transmission device for switching a working line and a protection line to transmit a digital signal.

[0002]

2. Description of the Related Art As an example of a conventional digital wireless transmission device for switching lines of this type, Japanese Patent Laid-Open No. 58-12743 is known.
No. 6 and Japanese Patent Laid-Open No. 2-20140, and the block diagram thereof is shown in FIG.

In FIG. 2, two working lines 1 and 2,
One spare line 3 is provided. Signal input 101
The line from the signal input to the signal output 113 via the transmission line 108 is the working line 1, and the line from the signal input 201 to the signal output 213 via the transmission line 208 is the working line 2. Then, from the signal input 101 or 201 to the transmission line 8
The line leading to the signal output 113 or 213 via the line is referred to as the protection line 3.

In the working line 1, a transmission digital signal is applied from an input 101 and is branched into two by a branch circuit 102. The one branch output is code-converted by the transmission code conversion circuit 105. The code used here is for facilitating timing extraction in baseband transmission,
It is a code format that suppresses continuous zeros. For example, HDB3
And BnZS code are used.

In the transmission code conversion circuit 105, the input 1
The coded signal supplied from 01 is decoded and derived,
The frame synchronization signal is added by the transmission signal processing circuit 106 and output to the wireless section transmission line 108 via the modulation circuit 107.

On the receiving side, the frame synchronizing signal added to the received signal processing circuit 110 via the demodulation circuit 109 is separated. In the switching circuit 111,
A signal of either the working line 1 or the protection line 3 is selected, converted into a zero suppression code again by the reception code conversion circuit 112, and derived as a reception digital signal from the output 113.

The working line 2 has the same structure as the working line 1, and its description is omitted. Also in the protection line 3, the transmission code conversion circuit 5, the transmission signal processing circuit 6, the modulation circuit 7, the wireless section transmission line 8, the demodulation circuit 9, and the reception signal processing circuit 10 have the same configuration as the working lines 1 and 2. . In addition, a distribution circuit 15 is added so that the output of the reception signal processing circuit 10 is branched and output to the working side.

The switching circuit 103 is for switching the transmission signal of the working line 1 to the protection line 3, and is usually A-
B and C-D are connected, and the branch output of the branch circuit 102 is terminated by the terminator 104. Incidentally, when the line is switched, A and C are connected. The same applies to the switching circuit 203.

A pilot signal generation circuit 16 is provided for monitoring the protection line 3, and this pilot signal (test signal) is transmitted to the protection line 3 via the switching circuits 203 and 103. The distribution circuit 15 supplies the pilot signal to the reception circuit 17.

The pilot signal receiving circuit 17 compares the received signal with the test signal to detect whether or not they match, and outputs the result to the output 18. If they match, it is confirmed that the protection line 3 is normal.

As a line switching method, for example, when a failure occurs in the working line 1, it is confirmed in advance that the protection line 3 is normal by the above-mentioned method, and then the switching circuit 103 sets the A
The signal of the working line 1 is transmitted to the protection line 3 by connecting between C and C. After confirming that the signal is input to the pilot signal receiving circuit 17 on the receiving side, the switching circuit 111 causes the distribution circuit 1
The signal from 5 is selected and output. As a result, the signal on the working line 1 is transmitted through the protection line 3.

[0012]

According to the conventional protection line monitoring method, the pilot signal generation circuit 16 for generating the test signal to be transmitted to the protection line and the pilot for judging whether the transmitted test signal is normal or not. Signal receiving circuit 17
Therefore, it is necessary to add circuits such as a clock oscillator and a PN code generator.

An object of the present invention is to provide a line monitoring system in which an increase in hardware is prevented by eliminating a pilot signal generating circuit, a receiving circuit and the like.

[0014]

According to the present invention, there is provided a line monitoring system in a digital transmission device including a working line and a protection line, wherein a transmitting digital signal transmitted through the working line at a receiving side. A line monitoring system is provided which is provided with a coincidence detecting means for detecting a coincidence between a signal and a transmission digital signal transmitted through the protection line.

[0015]

[Operation] Instead of sending a pilot signal for testing,
The digital signal to be transmitted is sent to the standby system at the same time as the active system, and the digital signals from both systems are compared on the receiving side. If they do not match, it can be determined that the backup line is abnormal.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and the same parts as those in FIG. 2 are designated by the same reference numerals. In the working line 1, the transmission digital signal is supplied from the input 101 and is branched into two by the branch circuit 102. One branch output is code-converted by the transmission code conversion circuit 105, and a frame synchronization signal is added by the transmission signal processing circuit 106. Then, the wireless section transmission line 1 is transmitted through the modulation circuit 107.
08 is sent.

On the receiving side, the signal is reproduced by the demodulation circuit 109, the frame synchronization signal is separated by the reception signal processing circuit 110, and output to the switching circuit 111. The switching circuit 111 is provided with a comparison function (not shown) for comparing the output of the received signal processing circuit 110 that has passed through the working circuit 1 with the output of the received signal processing circuit 10 of the protection line 3, and the comparison result is shown. The signal is sent to the terminal 114, and at the same time, either the current signal or the spare signal is selected and output. This output is converted into a zero suppression code by the reception signal conversion circuit 112 and is derived from the output 113.

The working line 2 is assumed to have the same structure as the working line 1. As for the protection line 3, the components from the transmission code conversion circuit 5 to the reception signal processing circuit 10 have the same configuration as the working circuit. In the distribution circuit 15, the output of the reception signal processing circuit 10 is branched to each side of the working lines 1 and 2.

A method of monitoring the protection line 3 will be described.
The switching circuit 103 is controlled in advance to connect between A and C. As a result, the transmission digital signal of the working line 1 (the input signal from the input 101) is transmitted to the protection line 3.

Therefore, on the receiving side, the outputs of the reception signal processing circuits 110 and 10 of the working line 1 and the protection line 3 are input to the switching circuit 111, and the two signals are compared.
If they match, it is understood that the protection line 3 is normal.

When there is a failure in the working line 1 (when a bit error is detected in the received signal processing circuit 110), the switching circuit 203 causes the working line 2 to be transferred to the protection line 3.
By transmitting the input digital signal (signal of the input 201) and detecting the coincidence between the two by the switching circuit 211 on the receiving side, the protection line can be monitored.

[0023]

As described above, according to the present invention, the transmitting side transmits the transmitting side digital signal of the working side to the protection line, and the receiving side compares the reproduced signals of the protection line and the working line. Since the coincidence detection is performed, there is an effect that the pilot signal generating circuit and the pilot signal receiving circuit are unnecessary.

[Brief description of drawings]

FIG. 1 is a system block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional line monitoring system.

[Explanation of symbols]

 1, 2 Working line 3 Protection line 5, 105, 205 Transmission code conversion circuit 6, 106, 206 Transmission signal processing circuit 7, 107, 207 Modulation circuit 8, 108, 208 Radio section transmission line 9, 109, 209 Demodulation circuit 10 , 110, 210 Received signal processing circuit 102, 202 Branch circuit 103, 111, 203, 211 Switching circuit 104, 204 Terminator 112, 212 Received code conversion circuit 114, 214 Data matching detection output terminal

Claims (3)

[Claims] 1. A line monitoring system in a digital transmission device including a working line and a protection line, wherein a transmission side digital signal transmitted through the working line and a protection line are transmitted at a receiving side. The line monitoring system is characterized in that a coincidence detecting means for detecting coincidence with the transmitted digital signal is provided. 2. The transmitting side is provided with branching means for branching and transmitting the transmission digital signal to the protection line in addition to the working line, and on the reception side, the working line and the protection line are respectively provided. 2. The line monitoring system according to claim 1, wherein the coincidence detecting means compares the transmitted digital signals transmitted via the same. 3. The at least two working lines are provided, and the receiving side is provided with selection means for selecting one of the two transmission digital signals of the two lines and transmitting the selected digital signal to the protection line. 3. The line monitoring system according to claim 1, which is characterized in that.