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Methods and apparatus for detecting cellular digital packet data (CDPD)

  • US 5,719,902 A
  • Filed: 04/18/1995
  • Issued: 02/17/1998
  • Est. Priority Date: 09/14/1993
  • Status: Expired due to Term
First Claim
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1. A spectral estimation method for detecting an overlay signal in a channel of a primary system, wherein the primary system has a plurality of channels in which the overlay signal might be present at any given time, and wherein the overlay signal is characterized by a clock frequency, the method comprising the steps of:

  • (a) determining which of the plurality of channel of said primary system are occupied by a signal by computing a ratio of spectral components within a prescribed spectral band to spectral components outside the prescribed spectral band for each of the plurality of channels;

    (b) asychronously enhancing a spectral component at said clock frequency by performing a non-linear operation on each of the plurality of channels determined to be occupied by a signal in step (a); and

    (c) deciding whether each of the plurality of channels is occupied by an overlay signal as a function of the enhanced spectral component.

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