Importance

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Abstract

In digital telecommunication switching systems the switch block includes an alarm monitor unit (AMU) which is used for initiating maintenance related commands in addition to monitoring, persistance checking and filtering alarm outputs. It is particularly useful in relieving the main processing system of routine alarm processing. The AMU collects line and switch block fault indicators from the digital line termination units DLT, applies persistance checks to determine if the alarm is transient or significant and depending on the outcome it identifies the precise location of the alarm and formats an error report to the processor. Each DLT communicates to and from an AMU by way of an alarm interface unit in the time switch serving the DLT using status and command highways respectively over 2048 kb/s balanced lines. The DLT uses 32 time slots to code-up status information in a time related manner (i.e. bit n of 256 has a defined significance such as speech parity error plane 1, channel m). The particular inventive concept is embodied in the arrangement where bit 6 of all channels is a 'flag' per DLT, indicating that the DLT has some error, alarm or other information, to convey to the AMU. The AMU can select status information from 1 of 32 DLTs but in parallel with the reception of such data the AMU continues to receive the bit 6 flag of all 32 DLTs, one DLT flag per channel period. Persistance logic in the AMU on the bit 6 flag is used as an interrupt pointer for the AMU selection of a total status stream from one particular DLT.

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First Claim