Ground Location Inertial Navigation Geopositioning System (Groundlings)

• US 20140002302A1
• Filed: 06/28/2012
• Published: 01/02/2014
• Est. Priority Date: 06/28/2012
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Robinson, Ian S.
• Granted Patent: US 9,075,126 B2
• Time in Patent Office: Days
• US Class Current: 342/357.32
• CPC Class Codes: G01S 11/08 using synchronised clocks
• CPC Class Codes: G01S 19/02 Details of the space or ground control segments
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H04B 7/1855 using a telephonic control signal, e.g. propagation delay variation, Doppler frequency variation, power variation, beam identification

Abstract

A ground location inertial navigation geopositioning system (GROUNDLINGS) end receiver (GER) can include a GROUNDLINGS module. The GROUNDLINGS module can be configured to generate a GER position using a time of flight (TOF) of a downlink pseudo-random noise (PRN) signal and a Doppler shift of at least one of the downlink PRN signal and a downlink tone signal on a common frequency carrier. The downlink PRN signal sent from a GROUNDLINGS satellite (GRS) to the GER can include a copy of an uplink PRN signal from a ground located transceiver (GLT) to the GRS. When used, the downlink tone signal can be received from the GRS.

Claims

1. A ground location inertial navigation geopositioning system (GROUNDLINGS) end receiver (GER), comprising:

a GROUNDLINGS module configured to generate a GER position using a time of flight (TOF) of a downlink pseudo-random noise (PRN) signal and a Doppler shift of at least one of the downlink PRN signal and a downlink tone signal on a common frequency carrier, wherein the downlink PRN signal sent from a GROUNDLINGS satellite (GRS) to the GER comprises a copy of an uplink PRN signal from a ground located transceiver (GLT) to the GRS, and the downlink tone signal is received from the GRS.

2. The GER of claim 1, wherein the GROUNDLINGS module is further configured to generate the GER position using the TOF of the downlink PRN signal and the Doppler shift of the downlink tone signal.

3. The GER of claim 1, wherein the GROUNDLINGS module further comprises:

a Doppler shift module configured to measure a Doppler shift in at least one of the downlink PRN signal and the downlink tone signal;

a range estimator configured to calculate a GLT range from the GLT to the GRS using GRS ephemeris information and a GLT location included in the downlink PRN signal and calculate a super-range measurement from a timing of the downlink PRN signal, wherein the super-range measurement represents a distance from the GLT to the GER via the GRS; and

a receiver location estimator configured to estimate a GER position using the ephemeris of the GRS, the GLT range, the super-range measurement, and the measured the Doppler shift in at least one of the downlink PRN signal and the downlink tone signal.

4. The GER of claim 3, wherein the receiver location estimator is further configured to determine an initial GER position from a GER range between the GRS and the GER and from a Doppler shift magnitude and a Doppler slope of at least one of the downlink PRN signal and the downlink tone signal.

5. The GER of claim 3, wherein the receiver location estimator is further configured to trend a range in a plurality of the downlink PRN signals and trends a Doppler shift in a plurality of the downlink PRN signals or downlink tone signals to generate the GER position.

6. The GER of claim 3, wherein the receiver location estimator further comprises at least one of an altimeter, a barometer sensor, and an altitude sensor for determining an altitude of the GER.

7. The GER of claim 3, wherein the receiver location estimator further comprises a sensor device selected from the group consisting of an inertial measurement unit (IMU), an inertial navigation system (INS), a motion sensor, a velocity sensor, an accelerometer, a magnetometer, a barometer, a rotation sensor, a gyroscope, a wheel counter, an odometer, a pedometer and combinations thereof for determining movement of the GER.

8. The GER of claim 1, wherein the GROUNDLINGS module is further configured to receive a second downlink PRN signal on a second frequency carrier and correct for ionospheric errors in the GER position using the downlink PRN signal and second downlink PRN signal.

9. The GER of claim 1, wherein the GROUNDLINGS module is further configured to decode the downlink PRN signal to generate a super-range measurement, wherein the super-range measurement represents a distance from the GPS to the GDER via the GSAT.

10. The GER of claim 1, wherein the GROUNDLINGS module is further configured to reset the clock bias by comparing the GLT range generated from the ephemeris of the GRS and the location of the GLT and the GLT range generated from the super-range or the Doppler shift in at least one of the downlink PRN signal and the downlink tone signal.

11. The GER of claim 1, further comprising:

a downlink signal receiver configured to receive at least one of the downlink PRN signal and the downlink tone signal;

a signal despreader configured to demodulate the downlink PRN signal, wherein the signal despreader is further configured for extracting at least one of a time at the GLT, a GLT location, and ephemeris information of a plurality of GRS.

12. A method for positioning using a ground location inertial navigation geopositioning system (GROUNDLINGS) end receiver (GER), comprising:

generating a position using a time of flight (TOF) of a downlink pseudo-random noise (PRN) signal and a Doppler shift of at least one of the downlink PRN signal and a downlink tone signal on a common frequency carrier, wherein the downlink PRN signal sent from a GROUNDLINGS satellite (GRS) to the GER comprises a copy of an uplink PRN signal from a ground located transceiver (GLT) to the GRS, and the downlink tone signal is received from the GRS.

13. The method of claim 12, wherein the downlink PRN signal is a frequency shifted copy of the uplink PRN signal using a different frequency carrier from the common frequency carrier.

14. The method of claim 12, wherein the downlink PRN signal and the downlink tone signal are sequentially transmitted on the common frequency carrier.

15. The method of claim 12, wherein generating the GER position further comprises:

extracting GRS ephemeris information and a GLT location from the downlink PRN signal;

determining a GLT range from the GLT to the GRS using the ephemeris of the GRS and the location of the GLT;

calculating a super-range measurement from a timing of the downlink PRN signal, wherein the super-range measurement represents a distance from the GLT to the GER via the GRS;

measuring a Doppler shift of at least one of the downlink PRN signal and a downlink tone signal; and

estimating a GER position using the ephemeris of the GRS, the GLT range, the super-range measurement, and the measured the Doppler shift in at least one of the downlink PRN signal and the downlink tone signal.

16. The method of claim 15, wherein measuring the Doppler shift further comprises:

receiving a second downlink PRN signal or a second downlink tone signal on a second frequency carrier; and

correcting a Doppler shift for ionospheric errors using the downlink PRN signal and second downlink PRN signal or the downlink tone signal and second downlink tone signal.

17. The method of claim 12, wherein the common frequency carrier operate in a frequency band greater than an ultra high frequency (UHF) band.

18. The method of claim 12, wherein the GRS is selected from the group consisting of a CUBESAT, a low Earth orbit (LEO) satellite, and combinations thereof, wherein the CUBESAT weighs less than 5 kilograms.

19. A computer program product, comprising a non-transitory computer readable storage medium having a computer readable program code embodied therein, the computer readable program code adapted to be executed to implement the method of claim 12.

20. A ground location inertial navigation geopositioning system (GROUNDLINGS) end receiver (GER), comprising:

a GROUNDLINGS module configured to generate a global position using a time of flight (TOF) of a broadcast signal from a known transmitter (KT) and a TOF and a Doppler shift of a copy of the broadcast signal relayed through a GROUNDLINGS satellite (GRS).

21. The GER of claim 20, wherein the GROUNDLINGS module further comprises:

a Doppler shift module configured to measure a Doppler shift in the copy of the broadcast signal;

a range estimator configured to calculate a KT range from the KT to the GRS using an ephemeris of the GRS and a location of the KT and calculate a super-range measurement from a timing of the copy of the broadcast signal, wherein the super-range measurement represents a distance from the KT to the GER via the GRS; and

a receiver location estimator configured to estimate a GER position using the ephemeris of the GRS, the KT range, the super-range measurement, a TOF the broadcast signal, and the measured the Doppler shift in the copy of the broadcast signal.

22. The GER of claim 21, wherein the GROUNDLINGS module further comprises:

a KT module configured to store a KT location and at least one modulation frequency transmitted by the KT; and

a GRS ephemeris module configured to store ephemeris information from at least one GRS.

23. The GER of claim 22, wherein the KT module and the GRS ephemeris are configured to update information from a GRS signal or a ground station signal including at least one of a KT location, a modulation frequency transmitted by the KT, and GRS ephemeris information, wherein the GRS signal is transmitted by the GRS and the ground station signal is transmitted by a ground station.