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DSP implementation of a cellular base station receiver

  • US 5,764,704 A
  • Filed: 06/17/1996
  • Issued: 06/09/1998
  • Est. Priority Date: 06/17/1996
  • Status: Expired due to Fees
First Claim
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1. A method of digitally demodulating an FM signal at one of an IF and base band frequency created by frequency modulating a carrier signal with a modulating signal, the FM signal having in-phase and quadrature components, wherein the in-phase component has the carrier signal and the quadrature component has the modulating signal, the method comprising the steps of:

  • sampling the FM signal at an appropriate sample rate to produce a digital channel signal;

    digitally filtering the digital channel signal to extract the carrier signal using a narrow frequency bandpass algorithm;

    digitally multiplying the carrier signal with the digital channel signal to form a mixed signal which comprises the modulating signal and the carrier signal shifted to a different frequency; and

    digitally filtering the mixed signal to recover the modulating signal.

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