Range estimation using floating reference points
First Claim
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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Abstract
A method of rapidly reacquiring a pseudonoise spread spectrum coded signal after short outages includes calculating the new positions of the moving stations relative to the old positions of the moving stations and for determining the accurate displacement and the accurate direction the platforms have moved in their new direction after a short time outage. The method includes calculating a triangle which includes the displacement between the moving stations'"'"' old position and the moving stations new position and the included angle between the direction of movement and the line of sight between said moving platforms at the time of outage. A range displacement adjustment is calculated on the basis of the triangle for each moving station and the range factor resulting from this calculation is applied to the PN generators of the receiver and transmitter in each of the moving stations to independently adjust for each station'"'"'s movement. The directional antennas of the moving stations are pointed in new directions toward the area in which the other moving station will be found. The directional antennas are moved simultaneously toward each other and a sweep or reacquisition adjustment of the PN generators of each moving station is made employing a small window of uncertainty which results in reacquisition of the PN coded signal being transmitted from the other station.
32 Citations
8 Claims
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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:
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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, and adjusting 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification