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Apparatus for transmission and reception of frequency modulated digital communication signals

  • US 4,304,004 A
  • Filed: 01/30/1980
  • Issued: 12/01/1981
  • Est. Priority Date: 02/13/1979
  • Status: Expired due to Term
First Claim
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1. A system for reception of digital communication signals which are impressed onto a carrier in the form of binary frequency modulation and radiated through a propagation medium which is subject to reflection, particularly, for reception in mobile stations wherein unsatisfactory reception which occurs as a result of phase and amplitude distortions is automatically detected to determine their origins with two supplemental arrangements, comprising receiving means including an IF stage receiving incoming signals, an FM demodulator receiving an input from said IF stage, an AM demodulator receiving an input from said IF stage, a dynamic distortion corrector receiving the output of said FM demodulator, a polarity integrator receiving an output of said dynamic distortion corrector and an input from said AM demodulator, an AM limiter receiving an output of said AM demodulator, an inverter receiving an output of said polarity integrator and an output of said AM limiter, a data analysis circuit receiving the output of said dynamic distortion corrector and outputs from said AM limiter, said inverter, and said AM demodulator, said data analysis circuit including an FM regenerator which receives the output of said dynamic distortion corrector, a phase follow-up device including a phase comparator (Ph) which receives the output of said FM regenerator and an output from said inverter, an AM decision device including a time evaluation circuit (ZB) which receives outputs from said inverter and said AM demodulator, a bistable trigger stage (BK2) which receives the output of said time evaluation circuit ZB, a change-over switch which receives the output of said bistable trigger stage BK2, the output of said phase follow-up device, the output of said AM limiter and the output of said inverter, said change-over switch controlled by the output of said bistable trigger stage, and a data regenerator receiving the output of said change-over switch.

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