Geolocation leveraging spot beam overlap
A method and system are disclosed for providing an estimate of a location of a user receiver device. The method and system involve emitting from at least one vehicle at least one spot beam on Earth, and receiving with the user receiver device a signal from at least one spot beam. In one or more embodiments, at least one vehicle may be a satellite and/or a pseudolite. The method and system further involve calculating with the user receiver device the estimate of the location of the user receiver device according to the user receiver device's location within at least one spot beam. In some embodiments, when the user receiver device receives signals from at least two spot beams, the user receiver device calculates the estimate of the location of the user receiver device to be located in the center of the intersection of at least two spot beams.
1. A method of providing an estimate of a location of a user receiver device, the method comprising:
emitting, from at least one vehicle with at least one of a known orbit or a known path, at least one spot beam on Earth;
receiving, with the user receiver device, a signal from the at least one spot beam as the at least one spot beam sweeps over the user receiver device as time progresses to obtain an amplitude of the signal from the at least one spot beam; and
calculating, with the user receiver device, the estimate of the location of the user receiver device by using: a known position of the at least one vehicle, a known direction and pattern of the at least one spot beam, and multiple amplitudes of the signal measured over time from within the at least one spot beam, as the at least one spot beam sweeps over the user receiver device over time.
2. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the method further comprises calculating a range from the at least one vehicle to a surface of the Earth.
3. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the method further comprises calculating a range from the at least one vehicle to the user receiver device.
4. The method of providing an estimate of a location of a user receiver device of claim 3 , wherein the calculating of the range from the at least one vehicle to the user receiver device comprises:
measuring a Doppler frequency offset of the at least one vehicle;
calculating a Doppler range estimate and pseudorange measurements using a Kalman filter; and
calculating a running estimate of the range from the at least one vehicle to the user receiver device.
5. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the user receiver device is located within a jammed environment.
6. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the user receiver device is located within an occluded environment.
7. The method of providing an estimate of a location of a user receiver device of claim 6 , wherein the occluded environment is indoors.
8. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the method further comprises using signal to noise (SNR) measurements from the at least one vehicle in order to further refine the estimate of the location of the user receiver device.
9. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the at least one vehicle is a satellite.
10. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the at least one vehicle is a pseudolite.
11. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the at least one vehicle is a space shuttle.
12. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the at least one vehicle is an aircraft.
13. The method of providing an estimate of a location of a user receiver device of claim 12 , wherein the aircraft is an airplane.
14. The method of providing an estimate of a location of a user receiver device of claim 12 , wherein the aircraft is an unmanned aerial vehicle (UAV).
15. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the at least one vehicle is a balloon.
16. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the at least one vehicle is a helicopter.
17. The method of providing an estimate of a location of a user receiver device of claim 9 , wherein the satellite is a low earth orbit (LEO) satellite.
18. The method of providing an estimate of a location of a user receiver device of claim 9 , wherein the satellite is a medium earth orbit (MEO) satellite.
19. The method of providing an estimate of a location of a user receiver device of claim 9 , wherein the satellite is a geostationary earth orbit (GEO) satellite.
20. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the at least one vehicle has a known orbit.
21. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the at least one vehicle has a known path.
22. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the user receiver device is mobile.
23. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the user receiver device is stationary.
24. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the at least one vehicle emits the at least one spot beam with at least one radio frequency (RF) antenna.
25. The method of providing an estimate of a location of a user receiver device of claim 24 , wherein the at least one spot beam is radiated from the at least one RF antenna as a fixed position beam.
26. The method of providing an estimate of a location of a user receiver device of claim 24 , wherein the at least one spot beam is radiated from the at least one RF antenna as a scanning beam.
27. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the user receiver device receives the signal from the at least one spot beam with at least one radio frequency (RF) antenna.
28. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the user receiver device uses a processor to calculate the estimate of the location of the user receiver device.
29. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein when the user receiver device receives a signal from only one spot beam, the user receiver device calculates the estimate of the location of the user receiver device to be located in a center of the one spot beam.
30. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein when the user receiver device receives signals from at least two spot beams, the user receiver device calculates the estimate of the location of the user receiver device to be located in a center of an intersection of the at least two spot beams.
31. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein when the user receiver device receives signals from at least two spot beams, the user receiver device calculates the estimate of the location of the user receiver device to be located at a centroid of centers of the at least two spot beams.
32. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the method further comprises determining a time the at least one spot beam rises (t RISE ) to a time the at least one spot beam sets (t SET ).
33. The method of providing an estimate of a location of a user receiver device of claim 32 , wherein the method further comprises determining, when mask angles are uniform in all directions with respect to the user receiver device, that the user receiver device is located at a center of the at least one spot beam in an in-track direction associated with the at least one spot beam at time=((t SET −t RISE )/2).
34. The method of providing an estimate of a location of a user receiver device of claim 32 , wherein the method further comprises determining, when mask angles are non-uniform in a spot beam rise direction and a spot beam set direction, that the user receiver device is located at a center of the at least one spot beam in an in-track direction associated with the at least one spot beam at time=((Δt True )/2), where (Δt True )/2=(Δt RcverMeasured +Δ βBias )/2.
35. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the user receiver device averages two or more estimates of the location of the user receiver device that were calculated over time in order to further refine the estimate of the location of the user receiver device.
36. The method of providing an estimate of a location of a user receiver device of claim 35 , wherein the user receiver device uses a Kalman filter in order to average the two or more estimates of the location of the user receiver device.
37. The method of providing an estimate of a location of a user receiver device of claim 35 , wherein the user receiver device uses a matched filter in order to average the two or more estimates of the location of the user receiver device.
38. The method of providing an estimate of a location of a user receiver device of claim 1 , wherein the estimate of the location of the user receiver is used by a global positioning system (GPS) in order to assist in rapidly acquiring the GPS signal.
39. A system of providing an estimate of a location of a user receiver device, the system comprising:
at least one vehicle with at least one of a known orbit or a known path, wherein the at least one vehicle emits at least one spot beam on Earth; and
the user receiver device, wherein the user receiver device comprises:
at least one radio frequency (RF) antenna, wherein the at least one RF antenna receives a signal from the at least one spot beam as the at least one spot beam sweeps over the user receiver device as time progresses; and
a processor, wherein the processor calculates the estimate of the location of the user receiver device by using: a known position of the at least one vehicle, a known direction and pattern of the at least one spot beam, and multiple amplitudes of the signal measured over time from within the at least one spot beam, as the at least one spot beam sweeps over the user receiver device over time.
40. The system of providing an estimate of a location of a user receiver device of claim 39 , wherein the user receiver device further comprises:
a local clock; and
a memory, wherein the memory is adapted to store successive spot beam identifying information that is recorded over time.
41. The system of providing an estimate of a location of a user receiver device of claim 39 , wherein the processor is to measure Doppler frequency offset of the at least one vehicle.
42. The system of providing an estimate of a location of a user receiver device of claim 39 , wherein the user receiver device further comprises an internal orbital model.
43. The system of providing an estimate of a location of a user receiver device of claim 42 , wherein the user receiver device receives orbital data information via transmissions from the at least one vehicle.
44. The system of providing an estimate of a location of a user receiver device of claim 42 , wherein the user receiver device receives orbital delta correction information via transmissions from the at least one vehicle.
45. The system of providing an estimate of a location of a user receiver device of claim 42 , wherein the user receiver device receives orbital delta correction information via transmissions from an earth based network.
46. The system of providing an estimate of a location of a user receiver device of claim 45 , wherein the earth based network is a cellular network.