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Land vehicle navigation system

  • US 4,949,268 A
  • Filed: 09/22/1988
  • Issued: 08/14/1990
  • Est. Priority Date: 09/22/1987
  • Status: Expired due to Fees
First Claim
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1. A land vehicle navigation system comprising:

  • a global positioning system (GPS) for receiving and demodulating signals from a plurality of satellites to fixedly determine the present travelling position of a vehicle;

    a satellite position computing means for determining the position of each of said satellites, based on almanac data supplied from said global positioning system;

    a heading detector for continuously detecting the heading of said vehicle;

    a geographical information means for storing a map indicated on an area in which the vehicle is to run and data representative of the distribution of the building height at said area;

    a visibility computing means for determining the visibility for signals from each of the satellites, based on signals indicative of the position of each satellite from said satellite position computing means, data representative of the heading of the vehicle from said heading detector and data indicative of the distribution of the building height from said geographical information means;

    a satellite selecting means for selecting a combination of satellites providing the maximum visibility at said area, based on signals indicative of the visibility from said visibility computing means; and

    a map and present position displaying means for displaying data representative of the map from said geographical information means and the present position of the vehicle,whereby a combination of satellites providing the maximum visibility for signals to be received by said global positioning system can be selected depending on the distribution of the building height in the area in which the vehicle is running.

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