文档介绍：sdh&pdh维护问题集锦(Sdh&pdh maintenance highlights)
Is the remote alarm of E1 sent by the remote or detected by the end? What causes the remote alarm?
In fact, the remote alarm of E1 is sent by the remote end and then detected by the end, so that the remote alarm can be seen at the end. The cause of remote alarm has several reasons: 1. lines, namely when the line breaker occurs, there will be an alarm; 2. frame structure problems lead to alarm; 3. line error rate exceeds the allowable minimum bit error rate of the line such as 10 - 6, will cause the alarm.
Remote alarm is also called on the end to end equipment alarm alarm. That is, RAI.
The role is to inform the end of the device: the end of the end is not good, may be the end of the transmission is not good, or may be received at the end is not good, or may be, the intermediate transmission link is not good.
LOF alarm in transmission
LOF E1 is the input signal corresponding to the step. At this point, the road will be all E1 business interruption, is due to the work or the end of the clock setting error caused. Check the work and the terminal equipment to set the clock, the clock is set to avoid conflicts or errors
LOF is frame out of step alarm.
The alarm occurs when the two devices are docked, and the
following problems should be examined:
1, check the clock of two sets of systems:
2, check the input jitter tolerance and output jitter;
3, check the grounding of the two sets of equipment (because the grounding is not good, resulting in the two devices butt joint phenomenon);
What is the bell flow in the switch?
The bell current source, also called the bell flow signal generator, is a special form of power supply. In munication exchange equipment, provide for the user telephone bell ringing signal source. The standard of bell source technology developed by the former Ministry of Posts and munications Standardization is as follows: sine wave, frequency 25Hz + 3Hz, output voltage 75V + 15V, distortion <1%.