Knowledge

The start, stop and feedback of the jet fan and the remote signaling and telemetry of the distribution box outside the tunnel are typical switching and low-speed signals in the tunnel electromechanical system. This article talks about how to use RS485/422 data optical transceivers to reliably move these signals to substations and monitoring rooms, focusing on signal classification, isolation and power supply.

The counting signals of the tunnel vehicle inspection coil and the instructions issued by the variable information board are mostly RS485 bus. This article explains how to use a video optical transceiver with reverse 485 to polish these low-speed control signals together with the image. What should be paid attention to in wiring, baud rate and bus segmentation, and a checkable configuration list for tunnel electromechanical integration.

If the number of cores for monitoring fiber optic cable laying is set too high, it will be expensive, but if it is set too little, you won't be able to add more points. This article explains how to settle accounts based on business core reduction, how to reserve spare fiber core proportions, and in what scenarios single-fiber links should be used to save cores. It also reminds the synchronous planning of down-end wiring capacity.

During the change of seasons from winter to spring, monitoring of optical fiber link alarms is concentrated, mostly related to condensation, dust, and cold shrinkage and bending. This article provides methods for inspection of key parts and retesting of control ledgers according to three types of hidden dangers.

Picture mosaic, smear, and single-point color cast fog correspond to three different reasons. This article provides the order of causes and check items according to the three layers of optical path, bandwidth and camera to help troubleshoot the problem before starting on the right layer.

After the fiber-optic monitoring was completed, the operation and maintenance was chaotic, mostly due to the lack of a link ledger. This article talks about the four elements of the ledger, the method of recording the light receiving power baseline when opening, and the three update actions to keep the ledger alive for a long time.

Replacement of old monitoring copper cables is not a one-time disassembly. This article talks about the construction sequence of the main trunk first and then the branches, the night cutover arrangements in batches by area, the observation items of the two-week parallel retention period, and the two ledgers that must be established before removing the old cable.

Many surveillance fiber optic transformations have been carried out in a superficial survey: problems were discovered only after the materials were ordered. This article provides a six-column record list for each point, explains how to actually measure the distance, how to verify the fiber core, and how to determine the lead position, and condenses the results into two pages of link list and material table.

The outdoor monitoring link occasionally disconnects, and the common cause is rat bites rather than equipment. This article organizes the inspection process based on the three-step process of looking at traces, opening boxes at actual measurement sections, and changing equipment for protection, and provides recommendations for inspection cycles based on the maintenance of safe city peripheral points.

Should we spend double the budget on armored jumpers at the end? This article uses the four quantifiable dimensions of insertion loss, minimum bending radius, tensile strength and unit price weight to compare armored and ordinary jumpers, and gives the usage boundaries based on risk segments.