JPS62104342A - Monitor device for operation margin extent of digital repeater - Google Patents

Abstract

PURPOSE:To monitor the extent of the operation margin of a digital repeater accurately from a distant place by providing an operation margin extent testing circuit to the input part of the digital repeater, controlling the operation margin extent testing circuit according to additional bits, and sending the code error rate during a test back to the distant place. CONSTITUTION:When the extent of the operation margin is measured, additional bits obtained by coding a number assigned to the PCM repeater 21, a measurement item, and measurement condition are inputted from a terminal station repeater, etc., through a PCM transmission line 20. The additional bits inputted to the PCM repeater 21 are separated by an additional bit separating circuit 26 and decoded by a control circuit 220 to discriminates the measurement item and measurement condition that the bits contain; and an attenuator inserting circuit 221 in the case of an input level margin extent or a noise generator 222 in the case of an S/N margin extent is controlled and error rate information from a code error counting circuit 28 is sent back to the terminal station repeater by a monitor information inserting circuit 34 through a transmission line 36.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an operating margin monitoring device for a digital repeater in a digital communication system such as an optical communication system or a PCM communication system.

[Conventional technology]

Conventionally, methods for monitoring the operation of digital repeaters include the LD bias monitoring method used in optical repeaters, and the PC
A pulse trio margin monitoring method employed in M repeaters is known.

FIG. 2 is a block diagram of an optical repeater that monitors the LD bias. The optical signal input to the optical repeater 1 from the optical transmission line 2 is converted into an electrical signal by the O/E conversion circuit 3, and then E1
The signal is converted into an optical signal by the 0 conversion circuit 4, subjected to relay operations such as waveform shaping, and sent to the optical transmission line 5. E
The bias value of the semiconductor laser (LD) in the conversion circuit 4 is monitored by the LD bias monitoring circuit 6, and the bias value of the semiconductor laser obtained by the LD bias monitoring circuit 6 is used for monitoring in the monitoring information insertion circuit 7. It is inserted into another optical transmission line 8 such as an optical transmission line and sent back to the monitoring light. In the same figure, reference numeral 9 denotes an O/E conversion circuit that converts the optical signal input to the optical repeater l via the optical transmission line 8 into an electrical signal, and 10
The monitoring information insertion circuit 7 connects the LD to the output of the O/E conversion circuit 9.
This is an E10 conversion circuit that converts an electrical signal into which bias monitoring information is inserted into an optical signal.

Figure 3 also shows the PC that monitors the pulse trio margin.
It is a block diagram of M repeater, and it is a block diagram of PCM transmission line 11 to P
The bipolar PCM signal input to the CM repeater 12 is B
The /U conversion circuit 13 converts the signal into a unipolar PCM signal, and the tuning circuit 17 equalizes the signal based on the reproduction signal 14, and then the U/B conversion circuit 15 converts the bipolar PCM signal into a unipolar PCM signal. and is sent to the PCM transmission line 16. To monitor the pulse trio margin of the PCM repeater 12, a pulse trio monitoring signal is input to the PCM repeater 12 via the PCM transmission line 11, and the pulse trio monitoring signal is input from the output of the U/B conversion circuit 15. Only the signal component corresponding to the signal is extracted by the bandpass filter 18 and sent back to the monitoring source via the monitoring transmission line 19, and the pulse trio margin is measured at the monitoring source based on the returned signal.

[Problem that the invention seeks to solve]

In this way, conventional digital repeaters are also equipped with some kind of monitoring means, but the error rate of digital repeaters has not yet been accurately monitored. The monitoring method in device 1 can only monitor the margin of the E10 conversion circuit 4 among all the circuits in the repeater, and although it can monitor the deterioration of the semiconductor laser, it cannot monitor the overall error rate. Even with the conventional pulse trio monitoring method of the PCM repeater 12 shown in FIG. 3, it is difficult to accurately grasp the correlation between the monitoring results and the error rate of the repeater.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an operating margin monitoring device that can accurately measure the operating margin of a digital repeater by preventing the vehicle from erroneously stopping the vehicle.

[Means for solving problems]

In order to achieve the above object, the present invention includes an additional bit separation circuit that separates additional bits from a signal input to the own digital repeater via a transmission path, and an additional bit separation circuit that is provided at the input section of the own digital repeater; An operation margin test circuit that tests the operation margin according to the contents of the additional bits separated by the additional bit separation circuit, and a signal input through the transmission line during the test of this operation margin test circuit. A code error rate detection circuit for detecting a code error rate and a monitoring information insertion circuit for sending the code error rate detected by the code error rate detection circuit to a transmission path and returning it are provided.

[Effect]

Monitoring source, for example, the number of the repeater being measured from the end station repeater.

When the additional bits containing information such as measurement items are input to the repeater under test via the transmission line, the additional bits are separated by the additional bit separation circuit, and the operating margin test circuit performs the operation margin test circuit according to the specified operating margin. Various operations for conducting tests, such as inserting attenuators for human power level margin tests,
During operations such as inserting noise for S/N margin testing and varying the center frequency of the equalizer tuning circuit for jitter margin testing, the transmission line When a digital signal is input to the repeater via
The code error rate is detected by the code error rate detection circuit, and the code error rate is inserted into the transmission path by the monitoring information insertion circuit and sent back to the monitoring source such as the terminal repeater.

〔Example〕

FIG. 1 is a block diagram of an embodiment of the present invention, showing an example in which the present invention is applied to a PCM repeater.

In the figure, a bipolar PCM signal input to a PCM repeater 21 via a PCM transmission line 20 is applied to a B/U conversion circuit 23 via an operating margin test circuit 22, where a unipolar PCM converted into a signal. B/
The output of the U conversion circuit 23 is input to an equalizer 24, where a signal equalized by a reproduced clock generated by a tuning circuit 25 is input to an additional bit separation circuit 26.

The additional bit separation circuit 26 is directly connected to the code error detection circuit 27 at the subsequent stage in order to relay the input signal to another repeater.
At the same time, if an additional bit is included in the human input signal, it is extracted and input to the control circuit 220 of the operating margin test circuit 22.

The code error detection circuit 27 detects code errors in the signal, and when a code error is detected, the code error counting circuit 28 is counted up. Further, for example, when code error processing is performed for a predetermined number of characters, the code error counting circuit 28 is reset.

The output of the code error detection circuit 27 is input to the U/B conversion circuit 29, where it is again converted into a bipolar PCM signal and sent to the PCM transmission line 30.

In addition, the bipolar P that is input to the PCM repeater 21 from another PCM transmission line 31 such as a monitoring transmission line or a downlink transmission line is also used.
The CM signal is converted to unipolar PCM by the B/U conversion circuit 32.
After being converted into a signal and equalized by an equalizer 33, it is input to a monitoring information insertion circuit 34. The monitoring information insertion circuit 34 is
The error rate information that is the output of the code error counting circuit 28 is inserted into the signal from the 33, and sent to the U/B conversion circuit 35, where it is converted into a bipolar PCM signal.
The M signal is sent to the PCM transmission line 36.

In this embodiment, the operating margin test circuit 22 is a PC
An attenuator insertion circuit 221 connected between the M transmission line 20 and the B/U conversion circuit 23, a noise generator 222, and an adder 223 that superimposes the noise signal generated by the noise generator 222 on the repeater input; The additional bit separated by the bit separation circuit 26 is decoded, and if the number of the own repeater is included, the antenna insertion circuit 221 is used to test the specified test item under the specified measurement conditions.
It is comprised of a control circuit 220 that controls a noise generator 222 and generates a signal that changes the center frequency of the tuning circuit 25.

In this embodiment, it is possible to measure the input level margin, S/N margin, and jitter margin of the PCM repeater 21, and when measuring each margin, the relay assigned to the PCM repeater 21 Additional bits encoding the instrument number, measurement items, and measurement conditions are input from a terminal repeater or the like via the PCM transmission line 20.

The additional bits input to the PCM repeater 21 are separated by an additional bit separation circuit 26 and input to the control circuit 220, and the control circuit 220 decodes the additional bits to determine whether or not it contains the number of its own repeater. If included, the measurement item and measurement conditions are identified, and the following control is performed depending on the content.

・Measurement item - Human power level margin In this case, the attenuator in the attenuator insertion circuit 221 is inserted between the PCM transmission line 20 and the B/U conversion circuit 23, and the attenuator value is changed to the value specified by the measurement conditions. let

When a PCM signal is input via the transmission line 20 with a predetermined attenuator value input to the input section in this way,
A code error is detected by the code error detection circuit 27, and error rate information corresponding to the attenuator value is output from the code error counting circuit 28. The error rate information is inserted into the signal from the transmission line 31 by the monitoring information insertion circuit 34, and is inserted into the signal from the transmission line 31. The signal is sent back to the end station repeater via 36. Therefore, the input level margin of the PcM repeater 21 can be monitored from the error rate information and the designated attenuator value at the terminal repeater.

- Measurement item = S/N margin In this case, the noise generator 222 generates a noise signal of a level specified by the measurement conditions, and the adder 223 adds it to the repeater input. The subsequent operation is the same as the input level margin test, and error rate information corresponding to the noise level is sent back to the end station repeater via the transmission line 36, and the error rate returned at the end office repeater side is From the information and the specified noise level, S/
Monitor the N margin.

-Measurement item = jitter margin In this case, a signal is applied to the tuning circuit 25 that changes the center frequency of the tuning circuit 25 by an amount specified by the measurement conditions.

As a result, the reproduced clock generated by the tuning circuit 25 fluctuates from its normal position, so it becomes possible to monitor the jitter margin by looking at the error rate at that time.

It goes without saying that the control circuit 220 does not insert the attenuator 221, superimpose the noise signal, or vary the center frequency of the tuning circuit 25 when the margin measurement is not instructed.

In the above embodiment, the measurement items include the manpower level margin,
Although there are three types of measurement, S/N margin and shifter margin, the present invention may be modified to measure one or two of them, and may be configured to measure other types of margin. You may do so. Further, although only an example applied to a PCM repeater has been shown, the present invention can be similarly applied to an optical repeater.

〔Effect of the invention〕

As explained above, according to the present invention, there is an operational margin for testing one or more types of margins such as input level margin, S/N margin, jitter margin, etc. at the input section of a digital repeater. A test circuit was installed, and the operating margin test circuit was controlled by additional bits sent from a remote location through the transmission line, and the code error rate during the test was determined within the repeater and sent back to the remote location. Therefore, the operating margin of the repeater can be accurately monitored from a remote location as an error rate, and the reliability of maintenance of the digital transmission line can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams of a conventional example. In the figure, 21 is a PCM repeater, 20.30.31.36 is a PCM transmission line, 22 is an operating margin test circuit, and 26
27 is an additional bit separation circuit, 27 is a code error detection circuit, and 28 is an additional bit separation circuit.
34 is a code error counting circuit, and 34 is a monitoring information insertion circuit.

Claims (1)

[Scope of Claims] An additional bit separation circuit that separates additional bits from a signal input to the own digital repeater via a transmission line; An operation margin test circuit that tests the operation margin according to the content of the separated additional bits, and detects the bit error rate of the signal input through the transmission line during the test of the operation margin test circuit. An operating margin of a digital repeater characterized by comprising a code error rate detection circuit that detects the code error rate, and a monitoring information insertion circuit that sends the code error rate detected by the code error rate detection circuit to a transmission path and returns it. Monitoring equipment.