Phase detecting method and phase detector and FM receiver using phase detecting method

A phase detector for detecting an instantaneous phase in a complex baseband signal, comprising:

• phase rotation means for rotating a phase of the baseband signal;
• rotation-angle data generation means for generating rotation-angle data indicative of the phase angle to be rotated in the baseband signal and for holding the rotation-angle data until it is renewed;
• and
• phase/rotation-angle equalization means for rotating the phase of the baseband signal so as to equalize with phase of the baseband signal to be obtained,
• wherein an output of the rotation-angle data generation means indicative of a rotation angle made equal by the phase/rotation-angle equalization means is output as a detection signal.

A method of detecting an instantaneous phase in a complex baseband signal, comprising the steps of:

• rotating the phase of the baseband signal;
• generating rotation-angle data indicative of a rotation angle of the baseband signal and holding the rotation-angle data until it is renewed;
• rotating the phase of the baseband signal so as to equalize the phase of the baseband signal with a desired phase of the baseband signal;
• and,
• outputting the rotation-angle data indicative of the rotation angle used to achieve desired phase.

A phase detector for detecting an instantaneous phase in a complex baseband signal, comprising:

• phase rotation means for rotating a phase of the baseband signal;
• rotation-angle data generation means for generating rotation-angle data indicative of the phase angle to be rotated in the baseband signal and for holding the rotation-angle data until it is renewed, said rotation-angle data generating means includes an output outputting a detection signal;
• and,
• phase/rotation-angle equalization means for rotating the phase of the baseband signal so as to equalize the phase of the baseband signal with a desired phase of the baseband signal, and for outputting a rotation angle,
• wherein said detection signal indicates said rotation angle used by the phase/rotation-angle equalization means to achieve the desired phase.

An FM receiver in which an FM signal is subjected to orthogonal demodulation with use of a orthogonal local signal having a frequency equal to a center frequency of the FM signal to obtain a demodulated first complex baseband signal so as to detect an original modulation signal with use of the demodulated first complex baseband signal, the FM receiver comprising:

• second complex baseband signal generation means for generating a second complex baseband signal having cosine and sine components of a phase change of the first complex baseband signal in a predetermined time interval .tau.;
• phase rotation means for rotating a phase of the second complex baseband signal;
• rotation-angle data generation means for generating data indicative of the phase angle to be rotated;
• and
• phase/rotation-angle equalization means for equalizing a rotation angle of the rotated second complex baseband signal to the phase change of the first complex baseband signal during the time interval .tau.,
• wherein an output of the rotation-angle data generation means indicative of the rotation angle equalized by the phase/rotation-angle equalization means is taken as a detection output.

An FM receiver in which an FM signal is subjected to orthogonal demodulation with use of a orthogonal local signal having a frequency equal to a center frequency of the FM signal to obtain a demodulated first complex baseband signal so as to detect an original modulation signal with use of the demodulated first complex baseband signal, the FM receiver comprising:

• second complex baseband signal generation means for generating a second complex baseband signal having cosine and sine components of a phase change of the first complex baseband signal in a predetermined time interval .tau.;
• phase region detection means for detecting one of a plurality of phase regions formed by equally dividing a complex coordinate plane by 2.pi./N radian (N being an integer of 4 or more) to which a phase of the second complex baseband signal belongs and outputting a detected result as a coarse phase value;
• rotation projection means for rotating the phase of the baseband signal by +.pi./N or -.pi./N radian according to a designation signal having a value of 1 or 0 indicative of an increase or decrease tendency in the phase of the baseband signal and outputting a value obtained by projecting the phase-rotated baseband signal onto a straight line which is perpendicular to a center axis bisecting the detected phase region and which has an origin at its intersection point whose positive direction corresponds to phase increasing direction in the detected phase region;
• integration means for integrating an output of the rotation projection means;
• quantization means for converting an output of the integration means to 1-bit binary value;
• delay means for delaying an output of the quantization means to obtain a delayed signal and outputting the delayed signal as the designation signal;
• phase synthesizing means for synthesizing the coarse phase value output of the phase region detection means with the output of the quantization means;
• and
• filter means for filtering an output of the phase synthesizing means,
• wherein the phase of the baseband signal is detected utilizing .SIGMA.-.DELTA. modulation.