Performance and Cost Global Navigation Satellite System Architecture

• US 20160011318A1
• Filed: 02/26/2015
• Published: 01/14/2016
• Est. Priority Date: 02/26/2014
• Status: Active Grant

• Current Assignee: PNT Holdings, Inc.
• Original Assignee: PNT Holdings, Inc.
• Inventors: Cohen, Clark Emerson
• Granted Patent: US 11,073,622 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 19/425 by combining or switching between signals derived from different satellite radio beacon positioning systems
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
• CPC Class Codes: G01S 19/45 by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system

Abstract

Significant, cost-effective improvement is introduced for Position, Navigation, and Timing (PNT) on a global basis, particularly enhancing the performance of Global Navigation Satellite Systems (GNSS), an example of which is the Global Positioning System (GPS). The solution significantly improves performance metrics including the accuracy, integrity, time to acquire, interference rejection, and spoofing protection. A constellation of small satellites employing a low-cost architecture combined with improved signal processing yields an affordable enabler for spectrum-efficient transportation mobility. As air traffic management modernization transitions to a greater dependence on satellite positioning, the solution provides aviation users new protections from both intentional and unintentional interference to navigation and surveillance. And in response to an era in which intelligent transportation is under development for automobiles, reliable where-in-lane positioning enables new applications in connected and autonomous vehicles. New military capability increases PNT availability.

Claims

1. A method for supporting resilient carrier phase positioning of at least one user device utilizing a service data processor, measurements received from Global Navigation Satellite System (GNSS) satellites, and measurements received from low Earth orbit (LEO) satellites, said measurements including carrier phase pseudoranges, comprising the steps of:

(a) the at least one service data processor accepting said measurements received from (i) at least one of said GNSS satellites by at least one LEO satellite, (ii) at least one of said GNSS satellites and the at least one LEO satellite by at least one ground reference station, and/or (iii) at least one other LEO satellite by the at least one LEO satellite via a LEO-to-LEO crosslink transmission;

(b) the at least one service data processor generating precise orbit and clock predictions for the at least one LEO satellite from available said pseudoranges; and

(c) the at least one service data processor disseminating said predictions to the at least one user device to enable the at least one user device to take into account the precise orbit and clock predictions when computing its position upon receiving signals and measuring additional carrier phase pseudoranges from GNSS and LEO satellites.

2. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 1, wherein

(a) the at least one service data processor accepts said measurements received from (i) at least one of said GNSS satellites by the at least one LEO satellite and (ii) at least one of said GNSS satellites and the at least one LEO satellite by the at least one ground reference station and

(b) the at least one service data processor (i) generates the orbit predictions from said pseudoranges received from at least one of said GNSS satellites by the at least one LEO satellite and (ii) generates the clock predictions from said pseudoranges received from at least one of said GNSS satellites and the at least one LEO satellite by the at least one ground reference station.

3. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 1, wherein said measurements received from the at least one other LEO satellite by the at least one ground reference station are from configurations wherein the at least one ground reference station is outside the footprint of the at least one LEO satellite.

4. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 1, wherein measurements received from LEO satellites by ground reference stations are unavailable.

5. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 1, wherein measurements received from GNSS satellites by LEO satellites are unavailable.

6. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 1, wherein (i) said at least one LEO satellite includes an oscillator of known stability coupled coherently to a receiver for use in measuring carrier phase pseudoranges from said GNSS satellites or from other said LEO satellites and a transmitter for use in broadcasting carrier phase to be received by said ground reference stations and (ii) the at least one user device endures loss of one or more clock predictions due to disablement of satellites, ground reference stations, service data processors, or data dissemination means via which the clock predictions are received.

7. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 1, wherein said at least one service data processor is integrated into a WAAS master station or a precise point positioning network operations center.

8. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 1, wherein said disseminating step is accomplished using SBAS satellites, Inmarsat Narrowband, NDGPS data broadcast, VHF aviation radio, 4G LTE, DOT ITS V2I 5.9 GHz standard broadcast, or said LEO satellites.

9. A method for supporting resilient carrier phase positioning of at least one user device utilizing a service data processor, measurements received from GNSS satellites, and measurements received from LEO satellites, said measurements including carrier phase pseudoranges, comprising the steps of:

(a) the at least one user device accepting precise orbit and clock predictions disseminated by at least one service data processor for at least one LEO satellite, said precise orbit and clock predictions being generated from available pseudoranges accepted by the at least one service data processor received from (i) at least one GNSS satellite by at least one LEO satellite, (ii) at least one GNSS satellite and the at least one LEO satellite by at least one ground reference station, and/or (iii) LEO-to-LEO crosslink transmissions between at least one other LEO satellite and the at least one LEO satellite; and

(b) the at least one user device taking into account the precise orbit and clock predictions when computing its position upon receiving signals and measuring additional carrier phase pseudoranges from GNSS and LEO satellites.

10. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, wherein (i) the precise orbit predictions are generated from pseudoranges accepted by the at least one service data processor received from at least one GNSS satellite by the at least one LEO satellite and (ii) the precise clock predictions are generated from pseudoraanges received from at least one GNSS satellite and the at least one LEO satellite by the at least one ground reference station.

11. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, wherein the pseudoranges accepted from the at least one other LEO satellite by the at least one ground reference station are from configurations wherein the at least one ground reference station is outside the footprint of the at least one LEO satellite.

12. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, wherein pseudoranges received from LEO satellites by ground reference stations are unavailable.

13. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, wherein pseudoranges received from GNSS satellites by LEO satellites are unavailable.

14. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, wherein (i) said at least one LEO satellite includes an oscillator of known stability coupled coherently to a receiver for use in measuring carrier phase pseudoranges from said GNSS satellites or from other said LEO satellites and a transmitter for use in broadcasting carrier phase to be received by said ground reference stations and (ii) the at least one user device endures loss of one or more clock predictions due to disablement of satellites, ground reference stations, service data processors, or data dissemination means via which the clock predictions are received.

15. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, further comprising the step of employing Receiver Autonomous Integrity Monitoring (RAIM) to weight a fusion of other sensors selected from at least one camera, lidar receiver, or radar receiver.

16. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, further comprising the step of forming coherent cross-correlations across at least one pair of satellites to combat potential interference.

17. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, wherein said GNSS and LEO satellites have known oscillator stabilities, and further comprising the step of receiving precise clock predictions of the GNSS and LEO satellites from the at least one service data processor and enduring subsequent loss of one or more clock predictions due to disablement of ground reference stations, service data processors, or data dissemination means via which the clock predictions are received.

18. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, wherein the method is carried out despite enduring subsequent loss of one or more clock predictions due to disablement of ground reference stations, service data processors, or data dissemination means therebetween or therefrom.

19. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, wherein said at least one LEO satellite is included in a constellation of said LEO satellites that minimize the number of required PRN codes through PRN code re-use.

20. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, further comprising the steps of:

(a) the user device, at such time as it is moving, receiving broadcasting signals from one or more terrestrial, free-running, pre-surveyed pseudolites of known oscillator stability and measuring carrier phase pseudoranges therefrom, and (b) incorporating the pre-surveyed locations and known oscillator stability of said pseudolites in said position computation.

21. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 20, wherein said pseudolites broadcast in the 5.9 GHz band.

22. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 20, wherein some or all of said pseudolites are mounted at street level.

23. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 20, wherein some or all of said pseudolites are mounted above said vehicles.

24. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 9, further comprising the steps of:

(a) receiving signals and measuring carrier phase pseudoranges from multi-band LEO, single-band LEO, and GNSS satellites;

(b) collecting service data processor precise orbit and clock predictions of both the LEO and GNSS satellites and road-specific ionosphere and troposphere estimates;

(C) applying said road-specific estimates to correct said single-band LEO satellite pseudoranges.

25. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 24, wherein one or more of said single-band LEO satellite signals are broadcast in the band centered at 1,575,420,000 Hz.

26. A method for supporting resilient carrier phase positioning of at least one user device as claimed in claim 24, wherein one or more of said single-band LEO satellite signals are broadcast in the band spanning 1,616,000,000 to 1,626,500,000 Hz.

27. A service data processor for supporting resilient carrier phase positioning of at least one user device utilizing a service data processor, measurements received from GNSS satellites, and measurements received from LEO satellites, said measurements including carrier phase pseudoranges, comprising:

(a) means for accepting said measurements from (i) at least one of said GNSS satellites by at least one LEO satellite (ii) at least one of said GNSS satellites and said at least one LEO satellite by at least one ground reference station and/or (iii) at least one other LEO satellite to the at least one LEO satellite via a LEO-to-LEO crosslink transmission;

(b) means for generating precise orbit and clock predictions for the at least one LEO satellite from available said pseudoranges received by the at least one LEO satellite; and

(c) means for disseminating said predictions to the at least one user device to enable the at least one user device to take into account the precise orbit and clock predictions when computing its position upon receiving signals and measuring additional carrier phase pseudoranges from GNSS and LEO satellites.

28. A service data processor for supporting resilient carrier phase positioning of at least one user device as claimed in claim 27, wherein

(a) the accepted measurements are received from (i) at least one of said GNSS satellites by the at least one LEO satellite and (ii) at least one of said GNSS satellites and the at least one LEO satellite by the at least one ground reference station;

and

(b) the generated orbit predictions are from said pseudoranges received from at least one of said GNSS satellites by the at least one LEO satellite, and the generated clock predictions are from said pseudoranges received from at least one of said GNSS satellites and the at least one LEO satellite by the at least one ground reference station.

29. A service data processor for supporting resilient carrier phase positioning of at least one user device as claimed in claim 27, wherein the measurements received from the at least one other LEO satellite by the at least one ground reference station are from configurations wherein the at least one ground reference station is outside the footprint of the at least one LEO satellite.

30. A service data processor for supporting resilient carrier phase positioning of at least one user device as claimed in claim 27, wherein measurements received from LEO satellites by ground reference stations are unavailable.

31. A service data processor for supporting resilient carrier phase positioning of at least one user device as claimed in claim 27, wherein measurements received from GNSS satellites by LEO satellites are unavailable.

32. A service data processor for supporting resilient carrier phase positioning of at least one user device as claimed in claim 27, wherein (i) said at least one LEO satellite includes an oscillator of known stability coupled coherently to a receiver for use in measuring carrier phase pseudoranges from said GNSS satellites or from other LEO satellites and a transmitter for use in broadcasting carrier phase to be received by said ground reference stations and (ii) the at least one user device endures loss of one or more clock predictions due to disablement of satellites, ground reference stations, service data processors, or data dissemination means via which the clock predictions are channeled.

33. A service data processor for supporting resilient carrier phase positioning of at least one user device as claimed in claim 27, wherein said service data processor is spaceborne.

34. A service data processor for supporting resilient carrier phase positioning of at least one user device as claimed in claim 33, further including coupled transmitters and receivers provided in an integrated circuit chipset hosted by said LEO satellite.

35. A service data processor for supporting resilient carrier phase positioning of at least one user device as claimed in claim 27, wherein said at least one service data processor is integrated into a WAAS master station or a precise point positioning network operations center.

36. A service data processor for supporting resilient carrier phase positioning of at least one user device as claimed in claim 27, wherein said disseminating means utilizes SBAS satellites, Inmarsat Narrowband, NDGPS data broadcast, VHF aviation radio, 4G LTE, DOT ITS V2I 5.9 GHz standard broadcast, or said LEO satellites.

37. A user device supported by a service data processor to utilize measurements received from GNSS satellites and measurements received from LEO satellites in order to compute a position of the user device, said measurements including carrier phase pseudoranges, comprising:

(a) accepting means for accepting precise orbit and clock predictions disseminated by the at least one service data processor for at least one LEO satellite, the precise orbit and clock predictions being generated from available pseudoranges accepted by the at least one service data processor received from (i) at least one GNSS satellite by the at least one LEO satellite, (ii) at least one GNSS satellite and the at least one LEO satellite by at least one ground reference station, and/or (iii) at least one other LEO satellite by the at least one LEO satellite as a LEO-to-LEO crosslink transmission; and

(b) computing means for computing the position of the user device by taking into account the precise orbit and clock predictions when computing the position upon receiving signals and measuring additional carrier phase pseudoranges from GNSS and LEO satellites.

38. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 37, wherein (i) the precise orbit predictions are generated from pseudoranges accepted by the at least one service data processor received from at least one GNSS satellite by the at least one LEO satellite and (ii) the precise clock predictions are generated from pseudoranges accepted by the at least one service data processor received from the at least one LEO satellite by the at least one ground reference station.

39. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 37, wherein the pseudoranges received from the at least one other LEO satellite by the at least one ground reference station are from configurations wherein the at least one ground reference station is outside the footprint of the at least one LEO satellite.

40. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 37, wherein pseudoranges received from LEO satellites by ground reference stations are unavailable.

41. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 37, wherein pseudoranges received from GNSS satellites by LEO satellites are unavailable.

42. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 37, said at least one LEO satellite includes an oscillator of known stability coupled coherently to a receiver for use in measuring carrier phase pseudoranges from said GNSS satellites or from other LEO satellites and a transmitter for use in broadcasting carrier phase to be received by said ground reference stations and (ii) the at least one user device endures loss of one or more clock predictions due to disablement of satellites, ground reference stations, service data processors, or data dissemination means via which the clock predictions are received.

43. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 37, wherein said computing means is coupled to a Receiver Autonomous Integrity Monitoring (RAIM) device.

44. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 37, wherein said computing means is coupled to means for employing said RAIM device to weight the fusion of other sensors.

45. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 44, wherein said other sensors include at least one of a camera and a lidar or radar receiver.

46. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 37, wherein LEO signals broadcast from each said LEO satellite to each said ground reference station and said user device use frequency bands that are the same as those used by GNSS satellites.

47. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 46, wherein said LEO signals are consistent with legacy or modern GNSS PRN codes.

48. A user device supported by a service data processor to utilize measurements received from GNSS and satellites as claimed in claim 47, wherein said GNSS PRN codes are selected from the following GNSS PRN codes:

GPS C/A, GPS P(Y), GPS M, GPS M′

, GPS L5, GPS L2C, GPS L1C, Galileo E1, Galileo E5a, Galileo E5b, Galileo E5, and Galileo E6.

49. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 46, wherein said LEO satellite signals are codes generated by a 128-bit AES counter producing a chipping rate of an integer multiple of 1,023,000 chips per second.

50. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 37, further comprising means for:

(a) the user device in motion receiving signals broadcast by one or more terrestrial, free-running, pre-surveyed pseudolites of known oscillator stability, the signals from the pseudolites including carrier phase pseudoranges, and (b) incorporating the pre-surveyed locations and oscillator stabilities of said pseudolites in said position calculation.

51. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 50, wherein said pseudolites broadcast in the 5.9 GHz band.

52. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 50, wherein some or all of said pseudolites are mounted at street level.

53. A user device supported by a service data processor to utilize measurements received from GNSS and LEO satellites as claimed in claim 50, wherein some or all of said pseudolites are mounted above where street vehicles operate.

54. A method for carrier phase positioning of a user device comprising:

(a) the user device receiving signals and measuring, over a measuring interval, carrier phase pseudoranges from a plurality of LEO satellites, each with a known orbit and an oscillator of known stability, with a user device;

(b) confirming that an observation geometry provides acceptable position accuracy over the measurement interval; and

(c) estimating a position of said user device.

55. A method for carrier phase positioning of at least one moving user device comprising the steps of:

(a) said at least one moving user device receiving and measuring carrier phase pseudoranges from one or more terrestrial, free-running, pre-surveyed pseudolites, each with an oscillator of known stability, and

(b) said at least one moving user device computing a position of said at least one user device from said pseudolite pseudoranges and pre-surveyed locations of said pseudolites.

56. A method of for carrier phase positioning of at least one user device as claimed in claim 55, further comprising the step of generating timely RAIM alerts.

57. A method for localizing one or more emitters comprising the steps of:

(a) collecting in a service data processor pseudoranges from GNSS or LEO satellite broadcasts measured by LEO satellites and/or ground reference stations;

(b) generating precise orbit and clock estimates of the LEO satellites and precise clock estimates of the ground reference stations;

(c) collecting in said service data processor wideband radio frequency (RF) sample streams of emitter signals measured by the LEO satellites;

(d) time and space registering of said samples streams according to said LEO satellite precise orbit and clock estimates; and

(e) cross correlating sample streams across pairs of LEO satellites to localize each emitter.

58. A method as claimed in claim 57, wherein:

said sample stream collecting step includes sampling of wideband RF sample streams of emitter signals measured by terrestrial receivers collocated with the ground reference stations,

said registering step includes time registering said terrestrial samples according to said precise clock estimates of the ground reference stations, and

said cross correlating step includes cross correlating both satellite-terrestrial and terrestrial-terrestrial sample stream pairs.

59. A method for supporting the resilient carrier phase positioning of one or more subscriber vehicles, comprising the steps of:

(a) collecting in a service data processor measurements from multi-band LEO satellites, said measurements from the multi-band LEO satellites including carrier phase pseudoranges from GNSS satellite;

(b) collecting in said service data processor measurements from ground reference stations, said measurements from the ground reference stations including carrier phase pseudoranges from multi-band LEO, single-band LEO, and GNSS satellites;

(c) collecting in said service data processor measurements from probe vehicles, said measurements from the probe vehicles including carrier phase pseudoranges from multi-band LEO, single-band LEO, and GNSS satellites;

(d) said service data processor generating precise orbit and clock predictions of LEO and GNSS satellites and road-specific ionosphere and troposphere estimates from said pseudoranges; and

(e) disseminating said predictions and estimates from said service data processor for at least one subscriber vehicle to enable the at least one subscriber vehicle to receive signals and measure carrier phase pseudoranges from multi-band LEO, single-band LEO, and GNSS satellites and estimate positions of the at least one subscriber vehicle.

60. A method for GNSS signal authentication, comprising the steps of:

(a) generating a watermark PRN waveform based on a watermark key that is initially secret, wherein said watermark key is arranged to enable a user device to perform watermark power checks on LEO satellite signals and perform a power solution and RAIM check employing all received signals;

(b) summing said watermark waveform with an open waveform; and

(c) broadcasting the LEO satellite signals including said summed waveform signals from one or more LEO satellites for receipt and access of said watermark key by the user device.

61. A method for GNSS signal authentication, comprising the steps of

(a) a user device receiving GNSS signals and LEO satellite signals, the LEO satellite signals including summed waveform signals, the summed waveform signals including a sum of a watermark PRN waveform and an open waveform, the watermark PRN waveform being based on a watermark key that is initially secret;

(b) accessing said watermark key by said user device;

(c) performing a watermark power check on each said LEO satellite signal; and

(d) performing a position solution and RAIM check employing all said received signals.

62. A GNSS signal authentication method as claimed in claim 61, wherein said LEO satellite signals include open waveform signals and the step of accessing the watermark key by the user device is enabled by disseminating said watermark key via one or more of said open waveform signals.

63. A method for GNSS signal authentication, comprising the steps of

(a) collecting in an authentication server from user devices signals stored as data received from GNSS satellites and one or more LEO satellites, wherein each signal from the one or more LEO satellites includes an encrypted waveform based on a traffic key that is secret;

(b) measuring pseudoranges for said stored signals using said traffic key to decrypt said LEO satellite signals and performing a position solution and RAIM check employing all said received signals, or

64. A GNSS signal authentication method as claimed in claim 63, further comprising the step of performing power checks on said LEO satellite signals.

65. A method for user position authentication, comprising the steps of:

(a) receiving a signal broadcast from one or more LEO satellites, wherein said signal from the one or more LEO satellites includes an encrypted waveform based on a traffic key that is secret;

(b) measuring pseudoranges from signals received from GNSS satellites;

(c) performing a position solution from said GNSS pseudoranges;

(d) accessing said traffic key;

(e) performing power checks on said LEO satellite signals; and

(f) using the position solution and the traffic key to decrypt the LEO satellite signals.

66. A user position authentication method as claimed in claim 65, wherein the step of accessing the traffic key includes the step of a user device receiving the traffic key from an authentication server, and wherein the steps of performing power checks and using the position solution and the traffic key to decrypt the LEO satellite signals are carried out by the user device.

67. A user position authentication method as claimed in claim 65, wherein said GNSS position solution and power checks are collected by an authentication server and said step of using the position solution and the traffic key to decrypt the LEO satellite signals is carried out by the authentication server.

68. A method for user position authentication, comprising the steps of:

(a) a user device receiving signals broadcast from one or more LEO satellites, wherein said signals from the one or more LEO satellites includes an encrypted waveform based on a traffic key that is secret;

(b) the user device receiving signals from GNSS satellites;

(c) the user device accessing the traffic key;

(d) the user device using the traffic key to decrypt the signals from the one or more LEO satellites;

(e) the user device measuring pseudoranges for the signals from the GNSS satellites and decrypted LEO satellite signals; and

(f) the user device performing a position solution and RAIM check employing all of said pseudoranges.

69. A method user position authentication method as claimed in claim 68, further comprising the step of performing power checks on said LEO satellite signals.

70. A method user position authentication method as claimed in claim 69, further comprising the steps of:

(a) digitally signing said position solution, RAIM check, and power checks;

(b) disseminating said position solution, RAIM check, power checks, and digital signature to an authentication server; and

(c) checking said disseminated data against said digital signature.

71. A method for fielding a positioning service for one or more users, comprising the steps of:

(a) broadcasting signals from one or more LEO satellites, wherein each said signal comprises an encrypted waveform based on a traffic key that is secret;

(b) receiving signals and measuring carrier phase pseudoranges from GNSS satellites with said LEO satellites;

(c) accessing said traffic key by one or more ground reference stations;

(d) receiving signals and measuring carrier phase pseudoranges from said GNSS and LEO satellites with said ground reference stations using said traffic key to decrypt said LEO satellite signals;

(e) collecting in one or more service data processors said pseudoranges;

(f) generating, encrypting, and disseminating from said pseudoranges precise orbit and clock predictions of said GNSS and LEO satellites to one or more user devices;

(g) accessing said traffic key and predictions by one of said user devices operated by an authorized user in return for said user paying an access fee to the service provider;

(h) receiving signals and measuring carrier phase pseudoranges from said GNSS and LEO satellites; and

(i) computing said user device position and performing a RAIM check employing all said pseudoranges.

72. A method for generating regional, high-power navigation signals, comprising the steps of:

(a) broadcasting a signal at a nominal power level from a network of LEO satellites;

(b) receiving signals and measuring pseudoranges from GNSS satellites with said LEO satellites in said network to an extent permitted by conditions;

(c) receiving signals and measuring pseudoranges from said GNSS satellites with said LEO satellites in said network to the extent permitted by conditions;

(d) receiving signals and measuring pseudoranges from said GNSS and LEO satellites with ground reference stations to the extent permitted by conditions;

(e) collecting in one or more service data processors said pseudoranges;

(f) generating from said pseudoranges orbit and clock predictions for said LEO satellites;

(g) disseminating to one or more user devices said predictions;

(h) broadcasting signals at a high power level from a subset of said LEO satellites over an area of operation;

(i) receiving signals and measuring carrier phase pseudoranges from said high-power LEO satellites with one of said user devices; and

(j) computing said user device position from said pseudoranges and predictions.

73. A method for generating regional, high-power navigation signals as claimed in claim 72, wherein said computing step includes computing said user device time.

74. A method for generating regional, high-power navigation signals as claimed in claim 72, wherein said pseudoranges are carrier phase pseudoranges.

75. A method for generating regional, high-power navigation signals as claimed in claim 72, wherein when said clock prediction is stale or otherwise unavailable to said user device, said computing step includes estimating said LEO satellite clock bias rate.

76. A method for generating regional, high-power navigation signals as claimed in claim 72, further comprising the steps of storing waste heat on each said LEO satellite during said high-power broadcasting and dissipating said waste heat during all other times.

77. A method for generating regional, high-power navigation signals as claimed in claim 72, wherein said storing and dissipating steps employ a phase change material therefore.

78. A system for the thermal control of a high-power regional navigation satellite system comprising a low earth orbit (LEO) spacecraft configurable to operate at high broadcast power for the duration of an orbital pass over an area of operation, the LEO spacecraft containing a device for generating navigation signals electrically coupled to one or more high-power amplifiers, the high-power amplifiers being electrically coupled to radiating antenna elements configured to broadcast over said area of operation, the high-power amplifiers being thermally coupled to a thermal storage element, and the thermal storage element being thermally coupled to a radiative thermal dissipation element.

79. The system of claim 78, wherein said thermal storage and radiative thermal dissipation elements include a phase change material that serves as a means for thermal storage and dissipation.

80. The system of claim 78, wherein said antenna elements are thermally conductive.

81. The system of claim 78, wherein said antenna elements are optically transparent to dissipating thermal radiation.

82. A method for providing agile, robust, and cost-effective services, comprising the steps of synthesizing various system-level functions for a global constellation of satellites by sequencing said satellites individually into various broadcast and receive modes depending on their orbital position, where said functions by region include at least one of the following functions:

(i) positioning, navigation, and timing using code and/or carrier;

(ii) rapid acquisition of accuracy and integrity;

(iii) emitter localization; and

(iv) radio occultation including ionospheric total electron content and atmospheric temperature, pressure, density, and humidity,

across various military, civil, and commercial domains.

83. A method of beamforming a space-borne distributed aperture, comprising the steps of:

(a) placing a finite number of randomly or quasi-randomly situated aperture elements free-flying in space;

(b) precisely spatially and temporally registering said aperture elements;

(c) synthesizing one or more high-resolution focal points; and

(d) containing said focal points within the Fresnel region of said distributed aperture.

84. The method of claim 83, further comprising broadcasting from said distributed aperture, in the region of one or more of said focal points, signals that are backwards compatible with existing GNSS signals.

85. The method of claim 83, further comprising the steps of electronically emulating within a focal region using said distributed aperture the broadcast of one or more virtual satellites, receiving said broadcast signals with a user device, and computing a position of the user device.

86. The method of claim 85, where said virtual satellites also emulate rapid angle motion.

87. The method of claim 83, further comprising the steps of:

(a) stationkeeping and attitude control of individual spacecraft associated with each said aperture element;

(b) maneuvering said spacecraft relative to a reference orbit; and

(c) commanding an ellipsoidal, Gaussian density configuration for said aperture elements.

88. The method of claim 87, further comprising the step of employing means for said stationkeeping and attitude control that require no onboard consumables.

89. The method of claim 87, further comprising the steps of launching and deploying said spacecraft, wherein said spacecraft have a flat, stackable form factor.

90. The method of claim 83, further comprising the step of centralizing a digital computation required for said beamforming.

91. The method of claim 90, further comprising the step of distributing the digital computation required for said beamforming among individual spacecraft carrying said aperture elements.

92. The method of claim 83, further comprising the steps of erasing via destructive interference all existing GNSS signals from within a focal region and adding back to said focal region one or more new and possibly false or misleading spoofing signals.

93. The method of claim 83, further comprising the step of emulating a Wi-Fi hot spot, mobile phone cell, or femtocell within a focal region.

94. The method of claim 83, further comprising the steps of concurrently carrying out one or more of the following signal intelligence steps:

(a) tracking a position of a specific cellular telephone within a focal region;

(b) monitoring signals of a specific cellular telephone within said focal region; and

(c) attenuating signals of all other cellular telephones outside said focal region.

95. The method of claim 83, further comprising the step of creating both a bi-static and multi-static radar for a target contained within a focal region usable for transmission and receiving across the entire visible sky.