DSP microprocessor decodes multifrequency combinations

Telecommunications is a very important field of application for Digital Signal Processing (DSP) techniques. The DSP techniques have important advantages like absence of drift in processing characteristics, reproducibility, flexibility and possibilities of multiplexing etc. This paper describes an important application of DSP techniques in communications switching system. Specifically, the paper describes an efficient DSP algorithm for the detection of MultiFrequency Combinations (MFCs). This function is required in the receiving part of the multifrequency signalling equipment, commonly known as MultiFrequency Receiver (MFR), used in digital central office switches for implementing Signalling System R2 (SS R2)-interregister signalling. This paper also describes a successful implementation of the algorithm in the realisation of multichannel MFR using a second generation fixed point DSP microprocessor viz TMS 320C25