Analysis of Automatic Optical Cable Monitoring System

Fiber-optic communication is favored because of its advantages such as large capacity, high transmission information quality, long transmission distance, stable performance, anti-electromagnetic interference, and strong corrosion resistance. Especially in the last decade, with the increasing demand for broadband services, optical fiber communication has been vigorously developed.

At present, the total length of optical fiber cables in China's communications industry has reached more than 2 million kilometers. In addition, the total length of optical fiber cables used by cable TV networks and private networks is estimated to reach more than 3 million kilometers. On the other hand, with the rapid development of Optical Synchronous Digital Transmission Network (SDH) and Dense Wavelength Division Multiplexing (DWDM) technology, the optical fiber transmission capacity is also growing at an unprecedented speed. But at the same time, cable maintenance and management issues are becoming increasingly prominent. With the increase in the number of optical cables and the aging of early laying of optical cables, the number of failures of optical cable lines is increasing. Fault Identification is difficult in the traditional optical cable line maintenance and management mode. Long troubleshooting time affects the normal operation of the communication network, resulting in huge economic losses each year due to communication cable faults. Therefore, the implementation of real-time monitoring and management of optical fiber lines, dynamic observation of Optical Fiber line transmission performance deterioration, timely detection and Forecast of Optical Cable hidden dangers, in order to reduce the incidence of Optical Cable blocking, it is vital to shorten the cable failure duration.

1 Preface

The Automatic Monitoring System of optical fiber cables (OAMSOpticalfibercableline Automatic Monitoring System) is a subnet of the transmission network management domain in China Telecom Management Network (TMN, it is an important technical means to effectively compress the duration of all obstacles and promptly discover hidden risks of optical cable lines. It uses computer technology, optical fiber communication measurement and other technologies to automatically and in real time monitor and test the quality and operation of optical fiber lines.

2. Necessity of Establishing an OAMS System

In the long-distance and local trunk cable transmission systems, the transmission equipment is equipped with a bit error rate (BER) monitoring equipment or monitoring unit. However, the traditional line maintenance department is not equipped with monitoring means. Generally, only when an BER alarm occurs, the crew should first determine the cause of the alarm, after finding out the cause is that the transmission line-optical cable, the crew will notify the relevant line maintenance department and report it to the competent authority, the line maintenance department then takes corresponding maintenance measures based on the learned deterioration of the optical fiber Line Transmission Performance. In the event of an optical fiber breakage obstacle, personnel are immediately dispatched to carry the instrument OTDR) to find the location of the optical fiber breakage, and at the same time organize personnel, machines, equipment, and so on for repair, that is, the commonly referred to as obstacle repair; if the total attenuation of the optical fiber channel increases, when the value is acceptable, it will be included in the line maintenance and transformation plan; if the value is unacceptable, the organization personnel will repair the channel, in order to improve its transmission performance and provide reliable circuits.

Apparently, if the maintenance department only uses the traditional BER monitoring, after the maintenance personnel determine the BER alarm caused by the transmission line, they will then notify the line maintenance department to repair, repair and transformation, therefore, the line maintenance department's mastery of the line condition is excessively dependent on the locomotive department and is passive. This makes it difficult to ensure smooth transmission of high-speed, broadband, and large-capacity optical cables. Therefore, it is necessary to establish an automatic monitoring system for optical cable lines in real time. The optical cable line automatic monitoring system provides an advanced maintenance means for the optical cable line maintenance department, this ensures the smooth, efficient, secure, and stable operation of the Cable Communication Department from passively accepting the information of the locomotive department to proactively controlling the transmission characteristics of optical cables.

Operating principle of the 3OAMS System

The optical fiber Line Automatic Monitoring System (OAMS) is an optical device that distributes a large amount of data to the optical fiber transmission performance, such as optical power and Back Scattering curves, report to the monitoring centers and monitoring stations at all levels, analyze and process the data, and timely and accurately report the operation of the Optical Cable System to maintenance personnel, enables maintenance personnel to promptly discover hidden risks and unexpected failures, and provides guidance for fault repair.

Composition of 4OAMS System

The OAMS system consists of PMC, LMC, and MS.

The monitoring center is responsible for controlling various monitoring stations. It is the center for data collection and processing, with controller servers, clients, and workstations) vro, Hub/switch hub, network adapter, MODEM, printer, and related software. PMC generally adopts the primary standby mode.

The monitoring station is responsible for remote automatic monitoring of optical cable lines, and tracking changes in optical fiber transmission loss. The monitoring module includes the alarm monitoring module, OTDR module, control module, power module, Programmable optical switch, and WDM division multiplexing) filters, MODEM, routers, network adapters, and corresponding software including OTDR simulation software) are usually installed in the standard rack of the transmission data center.

OAMS adopts a modular and distributed multi-level architecture to effectively prevent and reduce optical cable line barriers and achieve multi-level monitoring network interconnection.

5. Main functions of the system

Monitoring Station MS) optical power monitoring module of the acquisition unit AIU) to monitor and collect the optical power of the tested optical fiber, and transfer the collected data to the optical power control unit ACU ), the optical power control unit analyzes and compares the monitoring optical power data and reports the optical power data that exceeds the alarm threshold to the monitoring center LMC in a timely manner ), the monitoring center analyzes and collects statistics on the data transmitted by each optical power control unit, generates alarms for changes in optical power that exceed the threshold, and counts and judges the optical cable segments that are faulty, automatically and quickly start the OTDR and program-controlled optical switch OSW of the monitoring station to test the faulty optical cable segment. The obtained curve data is uploaded to the monitoring center, the monitoring center compares and analyzes the test curve with the reference curve to determine the location, type, and alarm level of the fault point. When a fault occurs, the O & M alarm information operation and maintenance personnel can be used, you can remotely notify relevant personnel by text message, phone, fax, or Email.

(1) National and Provincial Monitoring centers GMC and PMC)

Provides technical management of LMC and MS across the network, and monitors the running status of the entire monitoring network in real time. It provides maintenance and management reports, statistical analysis reports, and comprehensive information query functions.

(2) prefecture-level monitoring center LMC)

You can perform names, periodic and simulated alarm tests, and perform comprehensive analysis on the collected curves to promptly detect Optical Fiber deterioration and precisely locate Optical Fiber barrier points. The alarm reception function is available, based on the reference curve data, you can automatically determine the optical fiber barrier nature and notify the repair personnel of the barrier information by text message. Two-way data can be carried out with PMC, for example: curves, alarms, reports, status files, etc.

(3) Monitoring Station MS)

In MS, you can test the name, cycle, and obstacle alarms according to the central instructions. You can test the local function, simulate the OTDR analysis function, and report data.

Based on different needs, the on-site monitoring station can implement the following testing methods:

① Online monitoring. In the monitoring station, OTDR is tested based on different operating wavelengths of optical transmission devices, and wavelength division multiplexing (WDM), FILTER (FILTER), and Programmable optical switch (OSW) are used, it can monitor the running status of the used optical fiber in real time.

② Secondary fiber Monitoring. Monitor the running status of the standby optical fiber in the monitored optical cable line.

③ Cross-segment monitoring. By configuring the active devices and passive optical devices, mainly WDM and FILTER optical cables), you can remotely monitor the online or secondary optical fiber cables over the same optical cable segment. Cross-segment monitoring is generally used for trunk cable lines with relatively short and complex network formation, such as the domestic network and rural telephone.

Technical Features of The 6OAMS System

The system integrates modern network communication, computer communication, and optical fiber measurement technologies, and uses geographic information system (GIS) and global satellite positioning system (GPS) such technologies provide reliable guarantees for line information and line positioning, and enable remote, distributed, real-time, and online automatic monitoring for changes in transmission attenuation characteristics of optical fiber cables and fault blocking of optical fiber cables, it does not affect the transmission performance of the optical transmission system, so as to provide excellent circuits for customers.) and maintenance provides advanced maintenance means for the line.

7 Problems

After a long period of development, application and continuous improvement, the optical fiber automatic monitoring system has become an important Fault Locating Method in China's trunk cable maintenance work, it plays a huge role in the maintenance of the national backbone network. However, due to technology and other reasons, the system itself has some limitations.

(1) alarm signal extraction

Currently, the optical fiber monitoring system can be used to extract alarm information in three ways: the optical splitter can be used to extract 3% of the light in use, and the AIU and ACU can be used for analysis; the device relay optical disc is used to receive no light alarm signals. However, these three methods have some problems:

When using the AIU method, the system needs to distribute 3% of the optical power, which is not feasible for the relay segment with a small optical power surplus;

When the rack alarm signal is used, the monitoring system will respond to all the alarm signals of the rack, including power alarms and device alarms, to easily generate false alarms;

Because the relay discs of different manufacturers have different data formats, this method is difficult to implement and costly.

(2) attenuation of System Intervention

Because the system needs to be involved in WDM, FILTER and other passive optical devices, it will affect the optical power of the in-use system.

(3) Lack of fast optical path switching function

Currently, the monitoring system only provides the test, analysis, and alarm functions. After the optical fiber cable is blocked, maintenance personnel are still waiting for emergency repair at the site. There is no fundamental solution for instant optical path switching and communication restoration.

8 oams system development prospects

The optical fiber in the optical fiber cable may have physical defects, such as impurities and bubbles. In addition, the change of filling oil paste will affect the optical and mechanical properties of the optical fiber. In the external environment and external forces, the optical fiber is damaged due to the decrease of the optical fiber strength and the service life of the optical fiber is shortened. If we can understand the status of optical fiber cables, that is, we can change the passive mode to active mode and discover potential faults as soon as possible. However, it is difficult to implement these problems only through the OTDR test. To this end, you can introduce the B-OTDRBrillouinOpticalTimeDomain Reflectmeter) test device in the system. The B-OTDR is the use of the principle of fiber optic cable to accurately test the force and strain of optical fiber cables, even a very small bending can be accurate test. Previously, this product was only used to monitor minor movements of the earth's crust, small vibrations of large bridges, and other special requirements. Currently, this product is expensive. If conditions permit, you can add this device to the system to monitor the force-strain distribution of optical fiber cables on the optical fiber cables to predict potential faults.

In addition, the existing OAMS system has formed a computer network. This network is capable of carrying more information processing work in both computer processing capability and network structure. The existing system can communicate and share relevant information with inspection systems, report systems, office automation systems, optical cable geographic information systems, and other application systems, this greatly avoids repeated hardware investments. You can build a comprehensive management network for long-distance optical fiber lines, and incorporate daily maintenance of optical fiber cables into the management track, so that long-term maintenance can shift from manual management to computer management, it also provides a reliable guarantee for the maintenance of optical cables for the national backbone network, backbone network, and access network.

At the same time, the optical fiber communication network and the optical fiber line automatic monitoring system will continue to develop and develop in technology, especially with the implementation of the all-optical network in the future, A unified optical fiber communication network monitoring system may be formed by combining equipment monitoring management and line monitoring management.

1. Maintenance Method of Metro optical cable lines
2. Single-disk inspection should be paid attention to during Optical Cable Construction