Universal selector receiver for telephone exchanges - has processor and control for multifrequency code and dial-pulse signals

摘要

The universal selector receiver comprises a central processor (22), ROM (23), clock generator (29), input gate (21), output gate (24) and analogue/digital converter (28). A shared data bus connects the gates, CPU and ROM. The system can be in the form of a microprocessor. The A/D converter is fed from a crosspoint matrix (KF) with multi-frequency code and dial pulse signals. The ROM contains a program with which to check which of these signals is present. Multi-frequency code signals are sampled at a frequency of 8 KHz which is employed in many telephone exchange installations. The processing of the signals is done using quadrature correlation methods. If dial pulse signals are detected, the processor switches the clock generator to a lower rate.