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Digital block processor for processing a plurality of transmission channels in a wireless radiotelephony system

  • US 5,367,539 A
  • Filed: 12/31/1991
  • Issued: 11/22/1994
  • Est. Priority Date: 12/31/1991
  • Status: Expired due to Term
First Claim
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1. In a Frequency Division Multiple Access (FDMA) wireless radiotelephone system using FM modulated signals, a method for processing a plurality of FM information signals occurring in substantially adjacent frequency defined channels;

  • comprising the steps of;

    receiving a block of receive channels as a plurality of analog RF signals to be processed;

    converting the plurality of analog RF signals into a digitized time series;

    windowing the digitized time series into a plurality of defined frequency ranges equal to the number of defined channels;

    including;

    defining a window time span having an effective time duration less than a time duration of 1/4 cycle of a present baseband modulating frequency, andrestricting frequency domain sidelobes produced by windowing to a value less than a minimum acceptable post detection signal to noise ratio,generating Fourier coefficients with fast Fourier transforms in response to the windowing in order to identify the information signals of the individual channels of the digitized time series by recovering from the Fourier coefficients instantaneous frequencies from each FM carrier in each individual frequency defined channel;

    including;

    performing at least a first moment calculation that incorporates power spectra offset from a channel center frequency by an amount at least equal to a sum of a peak frequency deviation of FM modulation and a highest value of a modulating frequency, andexcluding from the first moment calculation power spectra offset from a channel center frequency by an amount that exceeds a sum of a peak frequency, deviation of FM modulation and a highest value of a modulating frequency,recovering the individual voice channels from the instantaneous frequencies of each FM carrier.

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