JPS6096049A - Fault locating system - Google Patents

Abstract

PURPOSE:To attain ease of fault location by disconnecting transmission of a main signal when a digital radio line is disconnected, transmitting only a pseudo random signal from a transmission section and allowing a relay station to compare the detected pseudo random signals mutually to discriminate faulty section. CONSTITUTION:In applying 0 to a terminal 30, a data signal and a pseudo random signal PNo transmitted from terminals 3, 4 of a speed converter 1 to terminals 22, 23 are blocked at AND circuits 31, 32 and 33 and two pseudo random signals PNt only shifted by n-bit each is outputted externally from output terminals 22, 23. A pseudo random signal supplied to a terminal 43 among pseudo random signals of two channels supplied to input terminals 42 and 43 is subject to n-bit delay at a delay circuit 2 and made in phase to the pseudo random signal supplied to the terminal 42. The two pseudo random signals are fed to an EX-OR circuit 44, its output is fed to a time counting circuit 45 so as to discriminate the presence of fault.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a fault detection method, and particularly to a fault detection method used in a digital wireless relay method.

(bl) Prior Art and Problems FIG. 1 (al shows a scrambling circuit used in a digital wireless system, and FIG. 1(b) shows a general configuration of a descrambling circuit.

The input side of the scrambling circuit shown in FIG. 1(a) is connected to a carrier terminal station, and the output side is connected to a modulator (the transmitting terminal station and modulator are not shown).

In the figure, a binary data signal 2 of, for example, 140 Mbit/sec is applied to input terminals 20 and 21 from a carrier terminal station.
The channel is converted into a data signal of, for example, 141 Mbit/s by inserting a meeting signal, a control signal, etc. in the speed converter 1, and is then converted into an exclusive OR (hereinafter EX-OR) signal.
(abbreviated as OR) is added to circuits 5 and 6.

On the other hand, the pseudo-random signal PN from the pseudo-random signal generator 3 is divided into two parts, one part being sent directly and the other being delayed by n bits through the delay circuit 2 and applied to the EX-OR circuits 6 and 5, respectively.

Therefore, the data signals of the two channels are scrambled by performing EX-OR with the H4W random signal PNt, but since the pseudo random rising signals added to each data signal are shifted by n bits, they become uncorrelated with each other.

Furthermore, the AND circuit 7 inserts the pseudorandom signal PN,o from the pseudorandom signal generator 4 into the signal of channel 2 in accordance with the period of the pseudorandom signal PNt, and
This pseudorandom signal PNo is used as a synchronization signal.

The scrambled data signals taken out from the terminals 22 and 23 pass through a modulator 2, a frequency converter, etc. (not shown), and then are sent from the antenna to the other station.

On the other hand, the input side of the descrambling circuit shown in FIG. 1 is connected to a receiver demodulator (not shown), and the output side is connected to a carrier terminal station (not shown).

Here, a part of the digital signal applied to the terminals 24 and 25 is detected by the synchronization circuit 1o on the reception side, which detects the synchronization signal PNo inserted into this digital signal, and when synchronization is established, a pseudo signal is generated to indicate that synchronization has been established. The movement of the random signal generator 12 is synchronized with the pseudo-random signal generator 2 on the transmitting side.

Therefore, EX-(IR circuits 8 and 9 perform descrambling by performing EX-OR with the received data signal using the pseudo-random signal PNr from the pseudo-random signal generator 12, and further speed conversion. The transmission rate is converted by the converter 13, and the original two-channel data signal of 140 h bits/second is taken out from the terminals 26 and 27.

Here, 1 of the pseudo(Gl random signal PNr divided into two)
part is supplied to the gx-oR circuit 8 through the n-bit delay circuit 11, and the remaining part is supplied directly to the EX-OR circuit 9.

Incidentally, since the relay operation at the relay station is often performed by regenerative relay, the scrambled data signal output from the receiver demodulator is sent as is to the transmitter modulator without being descrambled.

Next, when a failure occurs in the digital radio device having such a configuration, the location of the failure must be searched from the terminal station.

Conventionally, as a failure evaluation method for digital relay systems, a method has been put into practical use in which a terminal station transmits a specific pattern, for example 1010, and a relay station detects this pattern to evaluate a failed station.

That is, if there is no failure, everything can be detected correctly, but if it cannot be detected or the detected pattern is not 1010, etc., it is determined that there is a failure.

In the case of multilevel modulation, etc., there is a modulation spectrum represented by (Sinx/x), but when this is distorted due to fading etc., a part of this modulation spectrum is extracted and used for signal equalization and space saving. Since signal synthesis such as dihacity is performed to obtain the original spectrum, the method of inserting a specific pattern will turn the modulation spectrum into a line spectrum and the above operation will become unstable, so multilevel modulation etc. There was a problem that it could not be applied.

(C) Purpose of the Invention The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide a fault search method that can easily perform fault evaluation using pseudo-random signals. .

(dl.Structure of the Invention The purpose of the above invention is to provide a digital radio relay system in which a modulated wave modulated with a main signal scrambled with a pseudo-random signal is sent from a transmitter, when the digital radio line is disconnected. Provided is a fault search method characterized in that signal transmission is cut off, only the pseudo-random signal is sent from the transmitter, and the fault section is determined by mutually comparing the detected pseudo-random signals at the relay station. It is achieved by doing.

(e) Embodiment of the invention Figures 2 and 3 are examples for carrying out the present invention.
The figure shows a scrambling circuit.

In the figure, 1 is a speed converter, 2 is a delay circuit, 3 and 4 are pseudo random signal generators, and 5 and 6 are EX-
OR circuit, 7, 31 to 33 respectively AND circuit,
20 to 23.30 indicate terminals, respectively.

Note that the same symbols as in FIG. 1 indicate the same parts.

These blocks are connected as follows.

Terminals (l) and (2) of speed converter l are respectively terminal 2
0 and 21, terminal (31 is 77F circuit 31.EX-
01i circuit 5 to terminal 22, and terminal (4) to AND circuit 32. EX~OR circuit 6. The terminal 23 and the terminal 30 are connected to other terminals of the AND circuits 31, 32, and 33 via the AND circuit 7, respectively.

Further, the terminal (1) of the pseudo-random signal generator 3 is connected to the EX-OR circuit 5 and directly to the EX-OR circuit 6 via the delay circuit 2, and the terminal (1) of the pseudo-random signal generator 4 is connected to the AND circuit 33. are connected to the AND circuit 7 via the respective AND circuits.

The operation of the transmitting side connected in this way is as follows.

First, when O is applied to terminal 30, the terminal (3
) and (4) to the terminals 22 and 23, the data signal and pseudorandom signal PNo are sent to the AND circuit 31.
, 32 and 33, and are shifted by n bits from each other.
Only one pseudo-random signal PNt is present at the output terminals 22 and 2.
3 is output to the outside.

FIG. 3 is a diagram showing the configuration of the relay station, and FIG. 4 is a diagram for explaining the operation of FIG. 3.

Therefore, the operation shown in FIG. 3 will be explained with reference to FIG. 4.

In FIG. 3, among the two channels of pseudorandom signals applied to input terminals 42 and 43, the pseudorandom signal applied to terminal 43 is delayed by n pints in delay circuit 2, and then applied to terminal 42. It becomes in phase with the pseudo-random signal (Fig. 4(a) C, D, E).

These two carrier random signals are applied to an EX-OR circuit 44, the output of which is applied to a time counting circuit 45.

At this time, the state of the time counting circuit 45 is as follows depending on the presence or absence of a failure.

(2) Since 0 is not added to terminal 30 in FIG. 2 during normal data transmission, random signals are input to terminals 42 and 43 in FIG. 3. Therefore, random pulses are output to the output terminal F of the EX-OR circuit 44, so for example, if 10 bits of consecutive 0's are measured, 1
The time measurement circuit 45 that outputs the signal does not operate and the terminal 48 is set to 0.

■ When there is no line failure (Figure 4 (a)) Terminal 3 in Figure 2
When 0 is added to 0, pseudo-random signals with the same pattern are applied to the EX-OR circuit 44 as described above, so the output terminal F of the EX-ORR circuit becomes a series of O's (4th (a) Figure F). Therefore, the time measuring circuit 45 counts up and l is output from the terminal 48 (FIG. 4 (alG)).

■ When there is a line failure (Figure 4 (b)) For example, if an error pulse occurs in the data signal input to terminals 42 and 43, it will be the same as if a random signal was added as during normal data transmission. Therefore, the state 1 or O appears randomly at point F (Fig. 4G).

However, as mentioned above, unless there are 10 consecutive O bits, 1 is not output, so the output of the time measurement circuit 45 is as shown in FIG.
It becomes like G.

Incidentally, it is possible to reduce fluctuations in the output of the time measuring circuit depending on how many consecutive zeros are taken.

FIG. 5 is a diagram for explaining a determination method when the present invention is applied to an actual wireless line.

In the figure, 1 and 6 are transmitting terminal stations and receiving terminal stations, and 2
5 to 5 are relay stations.

In the figure, the receiving terminal station 6 detects a line abnormality based on the monitoring signal AL and sends a line test command to the transmitting terminal station 1 using the reverse line. In the transmitting terminal station 1 that receives this, the terminal 3 in Fig. 2
Add 0 to 0.

Therefore, the output of the time measurement circuit 45 is 1 at the relay station that has passed through the normal transmission line, but at the station after passing through the abnormal transmission line or station, the pulse train is disturbed or code distortion occurs. Therefore, the output of the time measurement circuit 45 becomes O. For example, if there is a failure between relay stations 3 and 4, relay station 4 or higher will become 0.

When this information is viewed at the receiving terminal station 6 using a remote monitoring device provided separately, it is found that the fault section is between 3 and 4.

The above explanation is based on the two-channel pseudorandom signal EX-
Although error detection is performed by passing the OR circuit 44,
The same operation as described above can be performed by comparing the frames of pseudo random signals of one channel as shown in FIG.

Here, 46 is a delay circuit, and the amount of delay is set to the length of one frame of the pseudorandom signal to be sent out.

(fl As explained in detail about the invention, according to the present invention, in a digital radio system using a multilevel variable/weak method, etc., a data signal sequence is scrambled with a pseudo-random signal, but this pseudo-random signal is not used. Since the fault evaluation is carried out based on the fault evaluation, it is possible to judge the fault section without disturbing the spectrum of the transmission line even during the fault evaluation.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a conventional scramble circuit and descramble circuit, Fig. 2 is a scrambler circuit diagram for implementing the present invention, and Fig. 3 is a schematic diagram of a relay station for implementing the present invention. Figure 4 is a diagram for explaining the operation of Figure J, Figure 5 is a diagram for explaining the determination when implementing the present invention, and Figure 6 is for another embodiment. Each is shown below. Chapter 3 Item 4 Part 4 (a) (b) 5 k Gt 1 / 0 0 0 No. 6

Claims (1)

[Claims] In a digital radio relay system in which a modulated wave modulated by a main signal scrambled with a pseudo-random signal is sent out from a transmitter, when the digital radio line is disconnected, the transmission of the cough main signal is interrupted and the pseudo-random signal is transmitted. A fault detection method characterized in that only a signal is sent from a transmitter and a relay station determines a fault section by comparing the detected pseudo-random signals with each other.