Abstract: A novel form of waveform coding is used, designated a "Critical Point Coder" (CPC). It operates by transmitting only those points in a waveform which are significant for defining its overall structure. The receiver reconstructs the missing points in the waveform using some sort of approximating interpolation. The Critical Point Coder uses a new approach to waveform coding. Rather than transmitting information about each sample as other waveform coders, the Critical Point Coder transmits information for only samples deemed critical to high quality reconstruction. The four major functions performed by the Critical Point Coder are (1) detecting which samples are critical, called critical points e.g.