About: Tandem signaling

Tandem signaling is the two-step conversion of a digital signal into an analog signal, followed by the reverse conversion. While there is a universal standard for analog signal transmission, digital signals may employ a variety of sampling rates and encoding methods (codecs). Any differences in sampling rate or encoding between transmitter and receiver introduce errors or artifacts in the resulting signal. When speech is being transmitted, as in audio telephone calls, tandem signaling may produce unintelligible results. Tandem signaling is an important evaluation criterion in the evaluation of speech coders.