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Position determination and message transfer system employing satellites and stored terrain map

  • US 4,839,656 A
  • Filed: 08/16/1984
  • Issued: 06/13/1989
  • Est. Priority Date: 08/16/1984
  • Status: Expired due to Term
First Claim
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1. A method for generating terrain map information representing local terrain elevations at a plurality of points on the earth'"'"'s surface, comprising:

  • placing a transceiver at a position of known latitude and longitude on the earth'"'"'s surface, said transceiver being operable to transmit a reply signal in response to a received interrogation signal;

    transmitting an interrogation signal to said transceiver;

    receiving a reply signal from said transceiver through a relay satellite at a known orbital location above the earth;

    calculating the terrain elevation at the transceiver location based on the transmission time of the interrogation signal and the arrival time of the reply signal from the satellite;

    entering said terrain elevation into a terrain map memory as a function of said latitude and longitude; and

    moving the transceiver to a different position and repeating the foregoing method steps.

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