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The eliminating of the bit error fault in one-way

Publication Date:  2012-09-24 Views:  184 Downloads:  0
Issue Description
There is a problem in the associated debugging before the conference in police bureau of Jiangxi Province that the branch conference site of Nanchang can see the figure of other sites normally, but in opposite, other sites can’t see its figures, especially when the camera moves. Observing in the control table, and it is found that the local end and far end of the FAPU synchronize and the bit error of the CRC check code is “0”.
Alarm Information
Handling Process
For the E1 was used in the conference, and there are two optical transceivers without multiple teeing devices and V35 interfaces in the link. It is the first time to have such problems. Test in the field with following steps:
1. Operate digital local loopback in the “Diagnose” in the control board of the terminal, and it shows that the figure in local and far end are normal and it work well too when we move the camera which indicates that there is nothing wrong with the terminal.
2. Take off the two BNC ports in the switch box between the optical transceivers and the terminals. Operate the physical loopback from the head of the local loopback to the terminal. The figures are normal when the camera is static or moving which indicates that there is nothing wrong with the link of the switch box.
3. For the fault is the bit error in one-way and is in the uploading link, exchange the two output 2M wires and the fault still exist. It indicates that there should be some problem in the transfer link.
4. Switch two links in the optical transceivers of both the province bureau and the city bureau for observing, and the fault still exists. With the connection between the optical transceivers and other devices is normal, we conclude that the optical transceivers works well.
5. Owing to the sending tower beside the city bureau, we consider that it is the strong signal interfering that leads to the fault. But we deny the possibility after analyzing.
At last, the FC was replaced by the city bureau and problems solved. And it proves that it is the fault of FC.
Root Cause
The network method of the conference television network is V35 interface. There are too many devices as well as too many problems. As what has been said before that we can only identify the fault in single step and overcome the influence brought by the default values. For instance, in this situation, the default value is “There should not be any problem in the FC”.