Demodulator for combined digital amplitude and phase keyed modulation signals

a digital carrier signal demodulation circuit comprising

• (A) a carrier recovery circuit comprising
• (a) a four-phase signal detection circuit means for detecting a received input signal with a reference carrier,
• (b) a regeneration circuit responsive to the detected received input signal for regenerating base band pulses of a first path signal in said received input signal,
• (c) a reverse-modulation circuit means for reversely modulating said received input signal with the base band pulses of said first path signal, thereby reproducing the carrier;
• (d) a phase comparator means for comparing the phase of said reference carrier with the phase of the signal provided by said reverse-modulation circuit, thereby providing a phase difference signal, and
• (e) a voltage-controlled oscillator means for providing said reference carrier phase locked to the phase difference signal from said phase comparator;
• and
• (B) a demodulation circuit means for regenerating base band pulses of a second path signal from said first path signal and said received input signal.