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  • What does Alarm Indication Signal (AIS) mean in a telecoms system?

    Posted by admin on February 26th, 2010 and filed under telecoms |

    Can someone please explain this — i’m having problems understanding it.

    If a system I am looking at is alarming with AIS, is it broke or is it receiving that from a remote part of the system?

    Thanks

    In the telephone system if there is a break in a cable or other service affecting problem, the two devices that are at the ends of the connection will send out an AIS signal to indicate to devices farther down stream in both directions that there is a problem with the link.
    The two end points of the circuit when they receive the AIS signal, will send out a RDI or Remote Defect Indication on their transmit. This will continue until the defect is fixed.
    When the circuit is working then there is framing information that is sent to indicate that the connection is good. When the connection is repaired the framing is sent, and the AIS and RDI signals will be stopped and the framing will be then sent again.

    One Response

    1. jivepacketrat Says:

      In the telephone system if there is a break in a cable or other service affecting problem, the two devices that are at the ends of the connection will send out an AIS signal to indicate to devices farther down stream in both directions that there is a problem with the link.
      The two end points of the circuit when they receive the AIS signal, will send out a RDI or Remote Defect Indication on their transmit. This will continue until the defect is fixed.
      When the circuit is working then there is framing information that is sent to indicate that the connection is good. When the connection is repaired the framing is sent, and the AIS and RDI signals will be stopped and the framing will be then sent again.
      References :
      Telco engineer and technician since 1971

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