Pulse or digital communications – Repeaters – Testing
Patent
1985-09-10
1987-06-23
Griffin, Robert L.
Pulse or digital communications
Repeaters
Testing
329 50, 329112, H04L 2716
Patent
active
046758828
ABSTRACT:
A digital FM demodulator is described. According to the principles of the present invention, a digital FM signal is demodulated by processing sampled input vectors of a quadrature FM digital signal centered approximately zero frequency. The sampled quadrature input vectors are quantized to lie within a predetermined magnitude range. The quantized vectors are coupled to a phase accumulator which generates a current coarse phase value related to input vectors of the quadrature FM signal. The output of the phase accumulator is also coupled to a vector rotation means which rotates the input vector to a predetermined quadrant to determine a fine phase value based on said rotated input signal vector. The fine and coarse values are then summed and output as a composite phase value, and digitally filtered by subtracting the value of the previous composite phase angle sample from the value of the current composite phase angle sample to produce a demodulated message sample.
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"Communications Receivers of the Future", Frank P. Chiffy and Bjorn E. Bjerede, Signal, Nov./Dec. 1985, pp. 16-21.
Jasper Steven C.
Lillie Ross J.
Chin Stephen
Downey Joseph T.
Griffin Robert L.
Jacobson James E.
Motorola Inc.
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