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Land vehicle navigation device comprising a filter unit for determining an optimum heading from presented orientation signals, and filter unit to be used in said navigation device

  • US 4,791,574 A
  • Filed: 08/25/1986
  • Issued: 12/13/1988
  • Est. Priority Date: 08/28/1985
  • Status: Expired due to Term
First Claim
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1. A navigation device for a land vehicle comprising:

  • an electronic compass for measuring the orientation of the vehicle and adapted to produce a first orientation signal by regular sampling of the measured orientation, a measuring unit operating independently of said compass for determining variations in the orientation of the vehicle and adapted to produce second orientation signals from regularly measured samples of the variations in the orientation, and a digital filter unit adapted to filter received first and second orientation signals, wherein the filter unit comprises a first low-pass filter for filtering first orientation signals received from the electronic compass, a high-pass filter for filtering the second orientation signals received from the measuring unit, a control unit which receives the first and second orientation signals and generates and supplies a first filter parameter control signal to the first low-pass filter and to the high-pass filter to control the filter characteristics thereof, and an output unit responsive to filtered orientation output signals of the first low-pass filter and the high-pass filter to produce from said received filtered orientation signals a weighted vehicle orientation signal which indicates the direction of movement of the vehicle.

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