Test word for conference digital exchange - uses digital test word to test storage for constituent PCM time-multiplexed parts of conference call

摘要

The telephone exchange is a PCM TDM type, with stores which are used for writting in the incoming words on the various TDM branches and for reading out the words to the conference connections. The method involves sending PCM code words into the various switching modules of the exchange being used to connect the conference parties, and reading out the words for comparison with a standard to ensure that all branches and modules being used are storing and allocating signals to the correct time slots satisfactorily. Incoming lines (Z1) are multiplexed (MUX) onto a data highway (SMLi) and converted to linear code (NL). After conference connection the linear codes are converted (LN) to PCM data highway code (SMLe) and output from the demultiplexer (DEM) (Z1). During conference setting-up, the speech stores (SK1, SK2) of each switching module are tested using test code words from the exchange common control. (MP1, MP2 of fig 1). The test words do not carry any all routing information. The test words can be used for fault localisation should a store (SK1, SK2) prove faulty.