The cost of the same tunnel optical cable is very different whether it strings the monitoring points into a chain, a loop, or a star point by point back to the management office. If you choose the wrong topology, there will either be insufficient fiber core, or a broken link will cause the picture and signal of half the tunnel to be lost.

Topology selected based on tolerance

• Point-to-point: Each point returns to the center independently, troubleshooting is straightforward, but it consumes fiber core. It is suitable for key points that cannot share the same fate, such as information boards and emergency calls.
• Chain cascade: string stations along the cave body to save fiber cores, and use intermediate stations8-channel video + 1-channel reverse 485 data video optical transceiverIf data is distributed and aggregated, a power outage at one location will affect the downstream.
• Ring shape: It forms a ring at both ends and can be bypassed if the link is broken at a single point. It requires equipment to support self-healing and has high operation and maintenance requirements. It is more commonly used in key sections of long tunnels.

Loss budget is determined in three steps

First look at the luminous power and receiving sensitivity range of the equipment, then add up the optical cable length according to the attenuation per kilometer, add the splice point and connector insertion loss, and finally leave about 3 dB margin at the receiving end to deal with temperature drift and aging. After calculating that the margin is less than one gear, change to a longer-range model or add a relay instead of letting the receiving end run close to the sensitivity threshold. This section a few kilometers outside the tunnel is especially easy to get close to the edge.

The spare fiber core must be lit during acceptance

The spare cores of ring and key links must be tested for light and the attenuation value must be registered upon completion, and a dust cap must be worn on the patch panel to mark the date. Otherwise, it will not be discovered until the day of switching that a certain core has been damaged by subsequent construction, leaving a false spare in vain. Wolf Light can be stocked in pairs according to the tunnel point list and tested one by one before shipment. The topology and gear calculation can be compared.Optical fiber project for vehicle monitoring system in highway tunnel in a provinceOr call 0755-83179002 to communicate.