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Range estimation using floating reference points

  • US 4,817,113 A
  • Filed: 05/01/1987
  • Issued: 03/28/1989
  • Est. Priority Date: 05/01/1987
  • Status: Expired due to Term
First Claim
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1. A method of reacquiring a pseudonoise (PN) spread spectrum coded signal transmitted from one moving platform to another moving platform after a outage, comprising the steps of:

  • calculating the distance X and the direction of movement at the new location from the last outage for each moving platform,calculating the included angle φ

    between the antenna pointing direction at the last outage and the direction to the new location for each moving platform,assuming a new pointing direction for the directional antenna which will include the circle of uncertainty of the other platform whose PN code signal is to be acquired during a sweep operation for each moving platform,calculating the angle θ

    between the new antenna pointing direction and the direction to the new location from the point of outage for each moving platform,calculating the length of the sides of the triangle Z and Y which are opposite the angles φ and

    θ and

    adjacent to side X for each moving platform,advancing or retarding the PN generators in each moving platform by range factor equal to Z minus Y,sweeping the directional antennas of each moving platform toward each other, andadjusting the PN generators and said moving platform through a predetermined window of uncertainty to rapidly acquire the PN coded signals being transmitted from the other moving platform.

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