Pulse code modulation. A lossless encoding technique widely used for working with audio, invented by Alec H. Reeves in 1937. Sometimes called LPCM for linear pulse-code modulation, which distinguishes the process from ADPCM. In pulse-code modulation, an analogue signal is linearly encoded to a series of binary numbers by sampling an analogue signal at regular intervals. See also encoding, linear, quantization.