Abstract: A quadrature demodulator for a phase shifted input pulse signal. The demodulator produces a four state digital code word on two output lines dependent upon the phase of the input signal. The input signal may have a phase shift, from the phase of the carrier signal, of zero degrees, +90.degree., -90.degree., or 180.degree.. The demodulator includes a clock-driven counter having an output signal at a fundamental frequency substantially identical to the carrier frequency of the input pulse signal. The counter produces additional output signals at frequencies which are multiples of the carrier frequency. The counter is synchronized with the input signal during a reference interval of zero phase shift, and a strobe circuit combines the various counter outputs to produce strobe signals to detect the phase shifted input signal.