Optical Transmission Equipment Maintenance Strategy
System-level and whole-unit maintenance: Fault causes should be analyzed and determined from the perspective of the entire optical transmission system. When the system is interrupted, we need to analyze, based on the symptoms and necessary operations, which part of the system or which equipment caused the problem, and perform preliminary fault location. For example, if a carrier circuit is interrupted, is it caused by a high-frequency channel problem or a carrier machine problem? Within the high-frequency channel problem, is it the high-frequency cable, the line trap, or other issues? Within the carrier machine problem, is it the local unit or the remote unit, etc.?
The determination of these fault locations requires measurement and testing with instruments and meters. Whether the signal level in the transmission path is normal, how large the frequency deviation is, and whether the waveform is correct — these are all bases for judgment.
To carry out this stage of work, one must first have a clear understanding and complete mastery of the composition of the entire system, its working principles, the functions and roles of each part, and the signal processing flow through the equipment. Otherwise, correct judgments cannot be made.
Board-level and component-level maintenance: After the analysis and judgment in the first stage, the faulty equipment can be identified, followed by second-level maintenance, i.e., board-level and component-level maintenance. In fact, there is no clear boundary between these two stages. The second stage is a continuation of the first, further identifying the faulty board and even the faulty component within the faulty equipment.
When the fault point is concentrated in a specific piece of equipment, that equipment must be tested. Follow the signal flow through the equipment step by step for tracking and testing, identify the interruption point, and determine the faulty board. For example, when a signal enters a certain board, under normal conditions the signal is processed within the board and output at a fixed value or within a value range. If measurement shows that this board has no output or the output deviates significantly from the nominal value, it can basically be concluded that this board is faulty. Once the faulty board is identified, locate the faulty component. Generally, a multimeter is used to measure whether the operating voltage and current of the component are normal, and with power off, measure its resistance value and check for open (short) circuits. The breakpoint can also be located by following the signal flow, depending on the specific situation.
Board-level and component-level maintenance requires familiarity with the working principles and composition of the specific equipment, the circuit principles of each circuit unit, and even the functions and characteristics of components, as well as the ability to correctly determine the signal characteristics of each part.
Optical Transmission Equipment Maintenance Measures
Just as with maintaining analog traditional communication equipment and systems, familiarity with the composition, working principles, and signal flow of the equipment and the entire system is the foundation of maintenance and repair. In addition, the following issues should be noted in actual maintenance work.
First, maintain a good equipment operating environment: including the quality of equipment power supply, ambient temperature, humidity, dust prevention, etc., in the equipment room, and whether these meet requirements. These are important prerequisites for ensuring equipment service life and reducing failure rates. Generally speaking, modern communication equipment has more stringent environmental requirements.
Second, modern communication equipment often no longer requires those routine and tedious adjustment and testing tasks, such as daily tests, monthly tests, and quarterly tests. It is only necessary to periodically use monitoring means for preventive surveillance. When there is no fault or no obvious signs of fault, random handling of the equipment is not advocated, and human-induced obstacles should be minimized as much as possible.
Third, when inspecting equipment and handling faults, special attention must be paid to not hot-swapping boards and to electrostatic protection. Always power off before inserting or removing boards, and develop the habit of wearing an anti-static wrist strap during work.
Fourth, the main method for handling equipment circuit faults is to replace the faulty plug-in unit/board. Where possible, keep spare plug-in units/boards that are prone to damage. Due to the high integration density, compact assembly, and fine wiring of boards, in most cases we cannot repair them ourselves; otherwise, the entire board may suffer irreparable damage. After identifying the faulty board, contact the manufacturer promptly for factory repair.
Fifth, software technology plays an increasingly important role in communications. Many equipment functions rely on software for implementation. Without mastering the relevant technology, it is impossible to master modern communication technology.
Sixth, fully leverage the role of the network management system. Modern communication systems all have relatively complete network management functions, which can monitor real-time indicators without interrupting services, and can perform fault monitoring, fault type determination, and fault location. It is an effective tool for preventive maintenance and fault handling.