Reverse-ephemeris method for determining position, attitude, and time

Patent metadata

Field	Value
Publication number	US-10254392-B2
Application number	US-201514848626-A
Country	US
Kind code	B2
Filing date	Sep 9, 2015
Priority date	Sep 9, 2015
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

A method to calculate position of a platform using a detection and ranging system coupled to the platform to transmit a signal to space object having a known ephemeris. The detection and ranging system receives the reflected signal from the space object. Taking the range of the platform from the space object using a time delay between transmission of the signal and receipt of the reflected signal and the range-rate using a Doppler frequency shift between the transmission of the signal and the receipt of the reflected signal makes it possible to calculate a position fix of the platform using the determined range, the determined range-rate, an altitude of the platform, and the known ephemeris of the space object.

First claim

We claim:

1. A method to calculate position of a platform comprising the steps of:
using a detection and ranging system coupled to the platform to transmit a signal to a space object having a known ephemeris;
receiving, at the detection and ranging system, a reflected signal from the space object, wherein the reflected signal is the transmitted signal reflected off of the space object;
determining a range of the platform from the space object using a time delay between transmission of the signal and receipt of the reflected signal;
determining a range-rate using a Doppler frequency shift between the transmission of the signal and the receipt of the reflected signal;
calculating a position fix of the platform using the determined range, the determined range-rate, an altitude of the platform, and the known ephemeris of the space object.

2. The method of claim 1 , wherein the detection and ranging system is selected from a group consisting of a Radar, Lidar, Ladar, and a Laser Rangefinder.

3. The method of claim 1 , wherein the platform is a ship.

4. The method of claim 3 , wherein the ship exists on the World Geodetic System of 1984 reference ellipsoid representing the approximate shape of the Earth.

5. The method of claim 1 further comprising the step of calculating an orientation and a clock offset of the platform by using the known space object location and the detection and ranging system as well as two angles to the space object and the rate of change of those angles.

6. The method of claim 5 , wherein the two angles to the space object are azimuth from true north and elevation above the horizon.

Assignees

• Us Navy

Inventors

• Reed Phillippe L W
• Mcbeth Michael S

Classifications

• G01S17/50

  Systems of measurement based on relative movement of target · CPC title

• G01S17/06

  Systems determining position data of a target · CPC title

• G01S13/588

  deriving the velocity value from the range measurement · CPC title

• G01S7/4808

  Evaluating distance, position or velocity data · CPC title

• G01S13/06

  Systems determining position data of a target · CPC title