Phase displacement modulator having four quadrant phases

Claim 1

A phase displacement modulator using four phases, said modulator comprising carrier signal source means having a predetermined carrier frequency, numerical signal generator means having four outputs which respectively deliver four signals each having the carrier frequency, means coupled to the four outputs of said generator means for adjusting a dephasing between the signals appearing thereat, the respective phases of said four outputs being 0, π/2, π, and 3π/2, encoder means having four inputs which are respectively connected to the four outputs of said numerical signal generator means, said encoder means having two governing inputs, means for respectively applying a modulating signal to the two governing inputs, said modulating signals being two successions of impulses, band pass filter means, said encoder means having four outputs which are connected to the input of said band pass filter means having an output which delivers a four state phase displacement modulated signal, and monostable multivibrator means driven responsive to a clock pulse stream having the same frequency as the binary modulating signal, said encoder means having a validation input which is connected to the output of said monostable multivibrator, the monostable multivibrator means having its output activated only during a fraction of the clock signal period.