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Adaptive identifying signal detector

  • US 5,020,141 A
  • Filed: 11/03/1989
  • Issued: 05/28/1991
  • Est. Priority Date: 10/02/1987
  • Status: Expired due to Term
First Claim
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1. In a radio receiver having:

  • receiver means for receiving, on any of a plurality of channels, radio frequency signals including an information signal, wherein some of said radio frequency signals also include squelch control signal;

    channel selection means for selecting which of said plurality of channels will be received;

    first detector means for detecting presence of a particular one of said squelch control signals within a first period of time;

    squelch means for selectively rendering said information signal audible and inaudible; and

    channel scanning means for causing;

    said channel selector means to select a particular channel;

    said channel selection means to retain said particular channel when saidfirst detector means detects said particular one of saidsquelch control signals; and

    said squelch means to render said information signal audible, an improvement comprising;

    second detector means for detecting presence of said particular one of said squelch control signals within a second period of time, wherein said second period of time is less than said first period of time; and

    control means for controlling which of said detector means is used to detect said particular one of said squelch control signals, such that said channel scanning means will cause said channel selection means to retain said particular channel and will cause said squelch means to render said information signal audible when either of said first and second detector means, as controlled by said control means, detects said particular one of said squelch control signals.

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