Short for Adaptive Differential Pulse Code Modulation, a form of pulse code modulation (PCM) that produces a digital signal with a lower bit rate than standard PCM. ADPCM produces a lower bit rate by recording only the difference between samples and adjusting the coding scale dynamically to accommodate large and small differences. Some applications use ADPCM to digitize a voice signal so voice and datacan be transmitted simultaneously over a digital facility normally used only for one or the other.
