• US 3,798,559 A
  • Filed: 04/17/1972
  • Issued: 03/19/1974
  • Est. Priority Date: 04/20/1971
  • Status: Expired due to Term
First Claim
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1. A noise reduction sYstem comprising:

  • an input terminal;

    an output terminal;

    variable gain means comprising a resistor, a capacitor and a variable resistance means operatively coupled together, said variable gain means connected between said input terminal and said output terminal; and

    a control means coupled at one end thereof to said input terminal and coupled at another end thereof to said variable resistance means, said control means comprising a series connection of an amplifier means, a rectifier means, a switching means comprising a constant voltage source and a switching circuit which is switched in accordance with a signal generated by said rectifier means, and a charge-and-discharge means comprising a capacitor, at least one resistor and at least one diode operatively coupled together and having different time constants for the charging operation and discharging operation thereof respectively, and being switched from one state to the other state by said switching means, whereby the gain of said variable gain means is controlled in accordance with the output signal of said from said charge-anddischarge means.

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