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Circuit for attenuating disturbing noise signals

  • US 4,313,215 A
  • Filed: 03/06/1980
  • Issued: 01/26/1982
  • Est. Priority Date: 03/10/1979
  • Status: Expired due to Term
First Claim
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1. A circuit for attenuating noise signals in an FM receiver, having an FM-demodulator coupled to a variable attenuator having a control input, wherein the output signal from said FM-demodulator is also applied to an absolute value function signal generator having an output signal from which a control signal for said variable attenuator is derived, which controls signal increases the attenuation of said variable attenuator when the absolute value of the demodulator output signal rises above a threshold level, characterized in that said circuit further comprises means coupled to the control input of said variable attenuator for generating a variable control signal dependent on the absolute value of said demodulator output signal when said absolute value exceeds said threshold level, said control signal having a first and a second time constant associated respectively with an increase or a decrease in the the absolute value output signal, said second time constant being considerably larger than said first time constant.

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