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Direct conversion radio receiver for FM signals

  • US 4,521,892 A
  • Filed: 09/08/1982
  • Issued: 06/04/1985
  • Est. Priority Date: 09/24/1981
  • Status: Expired due to Fees
First Claim
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1. In or for a radio receiver for receiving frequency modulated signals with a varying frequency difference from a carrier frequency, and in which mixing with a local oscillator is used to produce quadrature baseband channels, a demodulator circuit comprising a first channel in which a first baseband signal at the difference frequency will appear, a second channel in which a second baseband signal at the difference frequency will appear in quadrature with respect to the first channel and lagging or leading the first baseband signal in dependence upon the received signal frequency being above or below the local oscillator frequency, respectively;

  • and means for converting the outputs of said channels into an analog signal having an amplitude representative of the difference frequency.

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