Microprocessor based 9600 bps modem

A 9600 bps voice grade modem is described as a hierarchical connection of industry-volume second-sourced programmable computing elements. A review of 9600 bps modem functions is presented. The apportionment of these functions among processors in the architecture is then discussed. Means of hierarchical enforcement, economic use of discrete hardware, and provision for evolutionary product development are addressed. The application of an NEC 7720 Digital Signal Processor to realize a 60-tap complex adaptive equalizer, second-order phase-locked loop, and CCITT V.29 decision algorithm at 9600, 7200 and 4800 bps is presented in detail.