Pulse or digital communications – Receivers – Angle modulation
Patent
1994-12-15
1996-11-19
Chin, Stephen
Pulse or digital communications
Receivers
Angle modulation
375327, 375376, 331 31, H04L 2714, H04L 2716
Patent
active
055770738
ABSTRACT:
For use with a quartz angular rate sensor, a frequency and phase-locked synthesizer recovers a reference signal virtually free of phase noise, and generates a quadrature-phase reference signal for complex demodulation of the angular rate signal. The synthesizer also ensures a precisely adjusted phase shift of approximately zero across the drive tines of the sensor. Moreover, the digital synthesizer provides a precise numerical indication of the drive frequency, which can be used for compensation and automatic tuning of filters, such as a tracking filter, a filter in an automatic gain control, and notch filters in the phase and/or frequency detectors in the digital synthesizer. The tracking filter is used as a pre-filter for the synthesizer, and is responsive to a passband-width control signal generated from the magnitude of the frequency and phase error signal controlling the frequency generated by the synthesizer. Preferably the synthesizer has an oscillator controller for producing a pair of frequency control signals that are the sine and cosine of a frequency control parameter (.phi.), and one of these control signals is generated from the other by a polynomial approximation. To compensate for roundoff error, when one of the in-phase or quadrature-phase outputs has a magnitude less than a limit value, a compensated value for the other output is computed from an even polynomial of the magnitude.
REFERENCES:
patent: 4893316 (1990-01-01), Jane et al.
Chin Stephen
Montanye George A.
Rockwell International Corporation
Silberberg Charles T.
Streeter Tom
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