Abstract: A group demodulator for FDMA/PSK input signals comprising a down-converter for the input signals to convert these signals into in-phase and quadrature-related signals which are applied through analog-to-digital converters to a digital transmultiplexer. The digital transmultiplexer converts the signals into a number of channels of PSK modulated data. The output of each analog-to-digital converter is applied to an automatic threshold controller which detects the statistical bias of the input signal amplitude. Each automatic threshold controller provides an analog reference signal which is applied to a reference input of the associated analog-to-digital converter. The reference signal corrects any DC offset error for the analog-to-digital converter and prevents degradation in energy per bit-to-noise density ratio.