Specification of A/D and D/A converters for FDM telephone signals

Communication equipment requirements are generally established from the set of recommendations issued by the International Telephone and Telegraph Consultative Committee (CCITT). Those recommendations which influence the choice of the parameters of A/D and D/A converters for FDM signals are reviewed. Then a procedure for specifying such converters in terms of signal to total noise ratio is presented for two important applications, the 12-channel group codec and the 60-channel supergroup codec. The encoders and decoders can be synchronized and the advantage of time-sharing a single high-precision D/A module is stressed. A figure is also given for power consumption objectives.