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FM television telephone system

  • US 3,974,337 A
  • Filed: 05/23/1974
  • Issued: 08/10/1976
  • Est. Priority Date: 10/24/1967
  • Status: Expired due to Term
First Claim
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1. A television-telephone system, comprising, in combination:

  • a conventional telephone transmission line having a narrow band transmission characteristic;

    means for generating a video signal;

    means for generating a carrier wave signal having a frequency higher than and close to the maximum frequency of said video signal;

    means for frequency modulating said carrier wave by said video signal with a low index of modulation, such that the upper sideband portion of the modulated carrier is substantially the only portion of said modulated carrier wave which is not transmittable through said transmission line;

    means for transmitting said modulated carrier wave through said transmission line, except for said upper side-band portion; and

    frequency demodulating means, including non-linear amplitude limiting means for reproducing said upper side-band and for compensating for irregularities in the frequency characteristics of said transmission line and means for demodulating said transmitted modulated carrier wave with said reproduced upper side-band, whereby said video signal is transmitted through and reproduced from said conventional narrow band telephone transmission line.

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