Optical communication power line carrier communiations, microwave communiations, little by multiple access many communiation increasingly advantage and dominate, has now become the main transmission mode of the power communication network. It is based lightwave as the carrier, the optical fiber as the transmission medium, the signal transmitted from one to another at a means of communication. It has a large amount of information transmitted, distance, frequency bandwidth, high quality, strong anti-interference and radiation, and many other advantages, is a set of voice, images, data communication integrated transmission network. Therefore, how effective do light communication apparatus routine maintenance work, it is very important to ensure its safe and stable operation. Some of the problems in the processing and analysis process and the day-to-day maintenance of the common faults in the day-to-day operation and maintenance of SDH optical end devices, simple and summarized.
>> Master lines, equipment and instrumentation
The SDH system maintenance primarily light lines and equipment maintenance, and operation and maintenance personnel must be familiar with all aspects of the system in order to do the maintenance work, as follows:
a. The case of fiber optic cable lines: including fiber optic cable length, number of cores, connectors, patch cords and fiber attenuation value, prepared fiber.
b. Equipment: The main model of the device, configuration, machine-disk interface situation, all kinds of warining lights and indicator display and networking; the optical various test indicators, such as: transmitting and receiving optical power panel, sensitivity, etc.; equipment power supply situation; application of the ODF, DDF racks, VDF rack and network management system.
c.Instruments, tools circumstances: SDH optical transmission system commonly used instrument: optical power meter, OTDR, BERT, 2M, then the road analyzers, etc.. To master these functions and use of the instrument.
>>The basic idea of the fault location
1. The principle of fault location
Fault location should generally follow the first external, after transmission; first single station, veneers; first line, after the branch; first level, after low-level “principles.
2. Common fault classification
a. Fiber optic cable line fault. Including cable line interruption total attenuation of the optical fiber cable line is too large.
b. The pigtails faults. Including the pigtail off, pigtail bend radius is too small, the flange joint dust pigtail head is dirty.
c. Single disk faults. Inclduing circuit boards, 2M board, clock board, cross-board, control board device damage due to environmental temperature and humidity affect the board work properly.
d. Cable fault. Including 2M cable interrupted DDF frame side the 2M interface input / output port shedding or loose and cause poor contact and VDF rack card line loose.
e. Power system failure. Including Alternating Current power failure, equipment DC power-down and fuse faults.
3. Common method of fault location and troubleshooting
a. Alarm performance analysis
Obtained through network alarms and performance information to locate the fault. Comprehensive, detailed understanding of the whole network equipment or historical alarm information; indicator through the top of the cabinet and the veneer alarm indicator to get alarm information, and fault location. The general warning light is often red, yellow, and green, red emergency alarms and alarm, yellow indicates a minor alarm and general alarm, green indicates normal operation of the system.
b. Loopback method
The loopback method most commonly used SDH transmission equipment to locate the fault, a most effective method. The Loopback have a variety of ways, such as loopback and outer ring back, remote loopback and local loopback, line loopback branch loopback. Loopback operation should be carried out loopback business channel sampling, ie select a site from multiple faults site, select a business channel from selected sites multiple business channels; then draw the path diagram of the sampling business direction, the figure marked the source and sink of the business and through the site, occupied VC4 channel and time slot; Finally, paragraph by paragraph, loopback and locate the fault site and veneer.
c. Replacement Method
The replacement method is to use a working object to replace a object is not working properly, so as to achieve the positioning faults troubleshooting purposes. Where the object can be a piece of cable, a device, a veneer, a module or a chip.
Replacement metohd applies to exclude the transfer of external devices, such as fiber-optic trunk cables, switches, power supply equipment; fault location to a single station, single station within a single board or module is used to exclude.
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