Abstract: A demodulator for biphase, suppressed-carrier PSK signals, in particular useful for the demodulation of digital information transmitted as an auxiliary information in radio transmission channels, in particular of the "radiodata" kind comprising a filter for the extraction of the portion of the base band spectrum carrying said PSK signals, an amplitude limiter connected to the output of said filter for standardizing the amplitude of said PSK signals, a double-loop circuit receiving the limiter signal comprising a first loop associated with a data transition tracking loop decoder; a second loop constituted by a digital phase-locked loop. The double loop circuit cooperates with a stable oscillator for providing a frequency at a predetermined multiple of the frequency of the suppressed carrier of said PSK signal from the limiter signal.