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Communicating over power lines

  • US 3,909,821 A
  • Filed: 10/04/1973
  • Issued: 09/30/1975
  • Est. Priority Date: 10/04/1973
  • Status: Expired due to Term
First Claim
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1. Apparatus for communicating over power lines carrying power at power frequency comprising, a source of an audiofrequency signal within a predetermined frequency range within the frequency range of 1 kHz to 20 kHz, power amplifying means having a low output impedance coupled to said signal source for amplifying said audiofrequency signal, output terminal pair means for connection to a power line, and means for coupling said output terminal pair means to said amplifying means, said means for coupling having an output impedance presented to said output terminal pair means within the range of 0.1 to 4 ohms within said predetermined frequency range and a much higher impedance at said power frequency.

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