A compact multifunction signalling subsystem

Signalling subsystems are an indispensable part of a communication switching system. Compact, reliable, flexible and cost effective signalling subsystems are needed in the present day digital switching systems (DSS). This paper describes a single board versatile signalling subsystem based on digital signal processing (DSP)/digital techniques. Specifically, the design implements all the functions required in a DSS to implement dual tone multifrequency (DTMF, also known as multifrequency push button) signalling and signalling system R2 (SS R2). The complete DTMF subsystem and part of SS R2 are implemented using an ADSP-2105 DSP microcomputer; the remaining part of SS R2 is implemented using hardwired logic (random logic). The paper describes the algorithms used, their implementations and testing of this versatile signalling subsystem