Automatic dependant surveillance systems and methods

  • US 8,072,374 B2
  • Filed: 11/25/2008
  • Issued: 12/06/2011
  • Est. Priority Date: 11/27/2007
  • Status: Expired due to Fees
First Claim
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1. A communications system including an automated dependent surveillance-broadcast system and a global positioning system integrated into a single unit comprising:

  • a radio frequency receiver for receiving analog automated dependent surveillance-broadcast information at a selected transmission frequency and converting said information into digitized automatic dependent surveillance-broadcast information;

    a global positioning system receiver for receiving global positioning information including timing information; and

    a processing subsystem for decoding the digitized automated dependent surveillance-broadcast information in response to the timing information provided by the global positioning system receiver, wherein the radio frequency receiver comprises;

    analog processing circuitry for receiving the analog automated dependent surveillance-broadcast information at a selected transmission frequency and down-converting said analog information to an intermediate center frequency;

    circuitry for splitting the analog information into first and second sub-channels;

    circuitry for up-shifting the first sub-channel from the intermediate center frequency by a selected amount and for down-shifting the second sub-channel from the intermediate frequency by the selected amount;

    a first filter tuned to the frequency of the first sub-channel for generating a logic one output; and

    a second filter tuned to the frequency of the second sub-channel for generating a logic zero output.

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