Quasi-synchronous detection and demodulation circuit and frequency discriminator used for the same

A quasi-synchronous detection and demodulation device, comprising:

• quadrature detection means for performing a quasi-synchronous detection of a quadrature amplitude modulation signal and for issuing two series of quadrature detection signals;
• phase rotating means for rotating in phase said quadrature detection signals from said quadrature detection means to issue two series of demodulation signals with no rotation;
• carrier generating means for providing an output carrier signal having phase rotation information to said phase rotating means;
• frame-pattern detecting means for detecting a frame-pattern with two series of demodulation signals from said phase rotating means;
• and
• carrier phase compensating means for compensating an output carrier phase from said carrier generating means added to said phase rotating means to detect a normal frame pattern by means of said frame pattern detecting means.