Abstract: An adaptive threshold decision device for multistate modulation produces, at a symbol frequency, symbols dependent on the levels of a received demodulated baseband signal. It comprises a voltage divider, an adder for adding the baseband signal to a midpoint voltage which is substantially the mean of lower and upper voltages applied to the terminals of the voltage divider to produce a transposed signal, plural comparators for comparing the transposed signal with plural voltages at terminals of the voltage divider thereby producing comparison result signals, an encoder for deriving control words according to the comparison result signals, and control circuits for respectively and independently controlling at least the lower and upper voltages according to the control words.