JPH05500107A - optical communication system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] optical communication system The present invention relates to an optical communication system, particularly a lamp for early failure detection of such a system. Regarding an in-monitoring device.

When installed optical fibers are tested for obvious or suspected failures, One way to do this is to use an optical time domain reflectometer (OTDR). 0T DR includes a pulse source, usually a high power laser, of which single pulses are tested The background scattered light that is incident on the fiber and returned to the input end of the fiber is monitored. . A peak in the background scattered light indicates a fiber failure and is located at the input end of the fiber. For a given fault distance of each background scattering peak incident and reflected back It's because of the difference in time. once all detectable background scattered light has been received. Once sufficient time has elapsed, another pulse can be launched into the fiber. Wear. Pulse width can be varied for different dynamic range or resolution requirements . Therefore, for a given amplitude, increasing the pulse width allows long fibers to be monitored. make it possible. ie it increases the dynamic range. But unfortunately , increasing the pulse width decreases the spatial resolution (i.e. the minimum distance between distinguishable events). Make it less.

A particular limitation of using this type of 0TDR is that fiber optic communication systems are 0TDR connection is allowed, and system optical or 0TDR tracking may be adversely affected. must be separated or at least interrupted to prevent That's a good thing. As a result of this limitation, 0TDR is only useful after a failure has occurred. Therefore, it cannot be used for regular line management at the same time as data transmission.

An object of the present invention is to provide a line monitoring device that can be used simultaneously with data transmission. It is.

The present invention provides a test sequence generator that generates a test pulse sequence and a communication system. Repeat the test pulse sequence on the first end of the transmission line forming part of the system. means of injecting and transmitting to identify the background scattered test pulse sequence. correlating the signal received at the first end of the transmission line with the test pulse sequence; Correlator and background scattered test pulse sequence over a predetermined time of a fiber optic communication system that transmits system data, including an integrator that integrates Provide line monitoring equipment.

Therefore, this line monitoring device can operate when data is being transmitted, but That is not possible with current optical time domain reflectometers. This is the same as the system data. This is achieved by superimposing test pulses on or injecting them into slots. but However, for data transmission, the energy of the test pulse incident on the transmission line is It is necessary to minimize the possibility of 1M4N, and also to Interference with the transmitted data must be minimized. As a result, this This may be tested, for example, at 20 Mbits with a pulse width of typically 50 ns. By limiting the pulse width of the pulse to a pulse that is compatible with the system data, Relatively low energy pulses should be used compared to normal 0TDR pulse energies. Must be. However, using a test pulse sequence rather than a single pulse By using a low energy 0T, the test signal energy compensates for this requirement. It can be increased to use DR pulses.

In a preferred embodiment, the test pulse sequence is transmitted over the transmission line at the system data rate. Injected into the in. The test pulse should be as wide and high as the system data pulse. Preferably, the width and height of the pulses are approximately 100 degrees. background scattered light background scattered test sequences indicating changes in the fiber due to changes in intensity. continuously monitored from the entrance end of the fiber.

A test pulse sequence is included in each time-multiplexed transmission frame and the bar force or or volley chord position is effective.

The background scattered light test sequence is similar to normal 0TDR with only background noise. must be detected against background scattered light rather than system data , in the case of a duplex system, the system transmitted from the remote end of the fiber link. system data is coming. The background of the test sequence is scattered and reflected back to the background. A correlation technique is used to extract the background scattered light from the test sheet. Compare the incoming (reflected) signal with a replica of the test sequence to set the position of the test sequence. Compare. of the reflected back test sequence location and repeating pattern or interval. From the set-up, a sequence of successive reflections is added.

The intensity of the test sequence reflected back is low and a single test sequence is located at the fault location. The test sequence reflected back because it cannot be expected to be used to indicate If possible, the values are integrated over a long period of hours or days, and compared to earlier integration patterns. In this way, it is generally not instantaneous. Changes to the pattern due to stress, deterioration, or splice loss that indicate sequential failure are At an early stage, before a failure becomes such that it interrupts normal system data. It is possible to detect the

The invention also provides a transmission line and a means for injecting a data signal into a first end of the transmission line. and a line monitoring device as limited above. provide.

A frame compiler controller injects a data signal into the first end of the transmission line. means for supplying system data to an input of the frame compiler controller; It is useful for the test pulse sequence to be fed to another input of the frame compiler It is. Frame compiler controller controlled and maintained by test pulse sequence Each test pulse is inserted into a slot provided in the frame for the signal. Preferably, the sequences are multiplexed into respective frames.

The invention further generates a test pulse sequence and transmits the test pulse sequence. repeatedly incident on a first end of the line and receiving an optical signal at the first end of the line. data that extracts the background scattered test pulse sequence from the received signal. Provides a method for monitoring fiber-optic transmission lines without interrupting data transmission.

A dual optical communication system comprising a line monitoring device constructed in accordance with the present invention is implemented. BRIEF DESCRIPTION OF THE DRAWINGS Reference will now be made to the accompanying drawings, which are schematic illustrations of systems by way of example.

Referring to the figure, the line monitoring device flashes the test sequence pulses along line 2. A test sequence generator l is supplied to the input of the frame compiler controller 3.

The pulse width of the test pulse is limited similarly to the pulse width of the system data. typical is 50 nanoseconds for a 20 megabit data signal. System data is Also input to the frame compiler controller 3 along with any other elements to be transmitted. be done. The frame compiler control device 3 compiles each frame in a predetermined order. Time multiplex minutes. The bulk of each frame contains data, but is further managed and Also includes a slot for maintenance signals. If all time slots are not filled, the run Dumb data is inserted. The test sequence of pulses is the frequency assigned to the maintenance signal. It is possible to insert it into the frame part. Combined system data and and the test sequence are input to an optical transmitter 4 and sent along a fiber link 5 to a coupler 6. and 6- to an optical receiver 7 at the far end. cis in the direction of reflection system data (which can include different test sequences) is stored on the fiber link 5. It is transmitted from an optical transmitter 8 at the far end. This return data is passed through coupler 6'. and enters the fiber link 5. Therefore, the signal and light from the optical transmitter 8 The background scattered light of the signal from the transmitter 4 is directed towards the first end of the fiber link 5. proceed. This light is sent through a coupler 6 to an optical receiver 9.

The light incident on the optical receiver 9 is a relatively high power system device transmitted from the far end. Contains data signals. The relatively low intensity background scattered light originating from transmitter 4 is identified. superimposed on these high intensity signals without synchronization. background scattered light is data generates a voltage ripple superimposed on the data signal voltage. This ripple voltage is voltage level. Therefore, the comparator (forming part of the receiver 9) ) effectively ignores the ripple voltage and produces a digital output of the data signal. . The analog output of the receiver signal voltage (including ripple voltage) is along line 10. and is supplied to the correlator 11.

The test sequence is also input to the correlator 11 and is received by the correlator 11. The starting point of the test sequence for the signal is a rolling comparison. Therefore, it is determined. Codes for test sequences like bar force or volley codes. code is used, and such code shows high correlation when exactly synchronized with itself. The test sequence for the reflected signal itself or random or system data. The location of the background can be determined and the test sequence is It can be separated from the data. The output of the correlator 11 is one of the integrators 12. The frame synchronization signal from the frame compiler control device 3 is supplied to the input of the frame compiler controller 3. It is fed to another input of divider 12. Superimpose test sequence output from correlator 11 of the background scattered test signal by using a frame sync signal to Perform addition. Noise from transmitter 8 and system data can be monitored for changes background, which tends to average out leaving the scattered test sequence peaks.

Submission of translation of written amendment (Article 184-8 of the Patent Law) February 18, 1992

Claims (13)

[Claims] 1. A test sequence generator that generates a test pulse sequence and a test pulse sequence generator. a first end of a transmission line forming part of a communications system; means for injecting and receiving the sequence of test pulses at the first end of the transmission line; a correlator that identifies the background scattered test pulse sequence by correlating it with the detected signal; Integrate the background scattered test pulse sequence over a predetermined time A fiber optic communication system for transmitting system data comprising an integrator and an integrator. In monitoring device. 2. A test pulse sequence is charged to the transmission line at the system data rate. The line monitoring device according to item 1. 3. The test pulse has a pulse width similar to the system data pulse width and height. and a height, respectively. 4. Each test pulse sequence is included in its own time-multiplexed transmit frame. The line monitoring device according to any one of claims 1 to 3. 5. Claims 1 to 4 wherein the test pulse sequence is within a parka or golay cord. The line monitoring device according to any one of the above. 6. a transmission line; a means for injecting a data signal into a first end of the transmission line; An optical fiber comprising the line monitoring device according to any one of claims 1 to 5. Communications system. 7. A frame compiler controller inputs the data signal to the first end of the transmission line. system data to one input of the frame compiler controller. and the test pulse sequence is fed to another input of the frame compiler controller. 7. The optical fiber communication system of claim 6 provided. 8. The frame compiler controller allows test pulse sequences to be managed and maintained. Each test pulse sequence is inserted into a slot provided in the frame for each test pulse sequence. 8. The optical fiber communication system of claim 7, wherein the optical fiber communication system multiplexes the frames into each frame. 9. In a method for monitoring fiber optic transmission lines without interrupting data transmission, Generate a sequence of test pulses and apply the sequence of test pulses to the first repeatedly entering the end of the line and receiving the optical fiber signal at the first end of the line. , extracting a background scattered test pulse sequence from the received signal. method including. 10. Background scattered test pulse sequence is extracted by correlation and integration process 10. The method according to claim 9. 11. The width and height of each pulse is comparable to the width and height of the transmitted data pulse. 11. The method according to claim 9 or 10. 12. Each test pulse sequence is combined into a respective time-multiplexed transmit frame. 12. A method according to any one of claims 9 to 11. 13. The test pulse sequence is encoded by a Parker or Golay code. 13. The method according to any one of claims 9 to 12.