Geopositioning method using assistance data

• US 9,519,064 B2
• Filed: 03/11/2010
• Issued: 12/13/2016
• Est. Priority Date: 03/13/2009
• Status: Active Grant

• Current Assignee: Centre National D'Etudes Spatiales
• Original Assignee: Centre National D'Etudes Spatiales
• Inventors: Laurichesse, Denis, Mercier, Flavien
• Primary Examiner(s): Adams, Tashiana
• Assistant Examiner(s): Mull, Fred H
• Application Number:
  US13/256,260
• Publication Number:
  US 20120001799A1
• Time in Patent Office: 2,469 Days
• Field of Search: 342/357.26, 342/357.27, 342/357.41, 342/357.42
• US Class Current: 1/1
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

In order to enable a geopositioning receiver of a user to resolve phase ambiguities without necessarily using multi-frequency observations, assistance data is developed thanks to measurements made at a reference network (10, 12, 14) and sent to the receiver of the user. The assistance data used preferably consist of transmitter clock values associated with the carrier code sliding combination (Θ_eme) or with data sufficient for reconstructing said values. The transmitter clock values associated with the carrier code sliding combination (Θ_eme) can be reconstructed from iono-free transmitter clock values (h_eme) and clock biases (C′_eme), for example.

Claims

1. A method for performing geopositioning, by at least one radio navigation signal receiver of a reference network, using radio-navigation signals from a set of satellites of the reference network, each satellite of the set broadcasting at least a first radio-navigation signal on a first frequency and a second navigation signal on a second frequency distinct from the first frequency, the method of performing the geopositioning enabling the at least one radio navigation signal receiver to remove phase ambiguities, the method comprising:

receiving, by the at least one radio navigation signal receiver, for each satellite of the set that is visible from the said receiver, at least the said first radio-navigation signal;

performing, by the at least one radio navigation signal receiver, for each visible satellite, code measurements and phase measurements of the first radio-navigation signal received, said phase measurements presenting the phase ambiguities, the phase ambiguities including an ambiguity of an a priori unknown integer number of cycles;

receiving, by the at least one radio navigation signal receiver, a set of assistance data, wherein the set of assistance data comprises, for each satellite of the set of satellites, data sufficient for reconstructing a transmitter clock value associated with a carrier code shift combination, derived in a same manner across all the satellites and receivers of the reference network;

determining, by the at least one radio navigation signal receiver, for each satellite, a carrier code shift combination value from the code measurement and the phase measurement of the first radio-navigation signal, the phase ambiguities being removed as a result of the determining of the carrier code shift combination value;

determining, by the at least one radio navigation signal receiver, from said carrier code shift combination value the transmitter clock value associated with the carrier code shift combination, to obtain an unambiguous carrier code shift observable;

utilizing, by the at least one radio navigation signal receiver, the unambiguous carrier code shift observables to determine a precise position of the at least one radio navigation signal receiver.

2. The method according to claim 1, wherein the data sufficient for reconstructing the transmitter clock value associated with the carrier code shift combination comprise a satellite clock value associated with the carrier code shift combination.

3. The method according to claim 1, wherein the data sufficient for reconstructing the transmitter clock value associated with the carrier code combination shift value comprise iono-free transmitter phase clock values associated with a resolution of the ambiguities as well as smoothed transmitter parts of measurement residues obtained by:

receiving the code measurements and the phase measurements from the said radio-navigation signals recorded by the receivers in the reference network, said phase measurements having each an ambiguity that is an a priori unknown integer number of cycles;

resolving the ambiguities in the phase measurements on the first frequency in a same manner across all the satellites and reference receivers;

deducing a set of iono-free transmitter phase clock values arising from the resolution of said ambiguities and a set of iono-free receiver phase clock values arising from the resolution of said ambiguities;

calculating, for each satellite-reference receiver pair, a carrier code shift combination value from the code measurement and the phase measurement performed by the respective reference receiver for the respective satellite on the first frequency, and subtracting from this value a geometric contribution, a contribution of the iono-free receiver phase clock value and an iono-free transmitter phase clock value as well as a contribution of the resolved ambiguity of the phase measurement, so as to obtain a measurement residue;

separating, in a same manner across all the satellites and receivers of the network, each of the obtained measurement residues into a transmitter part and a receiver part; and

smoothing the transmitter part of the said measurement residues.

4. The method according to claim 3, comprising, for each satellite of said set of satellites, the action of calculating a transmitter clock value associated with the carrier code shift combination as the sum of the iono-free transmitter clock value and the smoothed measurement residue.

5. The method according to claim 3, wherein the smoothing of the transmission parts of the said measurement residues is performed each time by fitting a sine function with a period of 12 hours.

6. The method according to claim 1, wherein the first frequency is selected from a list comprising 1575.42 MHz, 1227.6 MHz, 1176.45 MHz, 1207.14 MHz, 1278.75 MHz, 1561.098 MHz, 1589.742 MHz, 1207.14 MHz, and 1268.52 MHz.

7. The method according to claim 1, wherein an accuracy of said precise position being on a range of 20 to 50 centimeters.

8. The method according to claim 7, further comprising:

increasing the accuracy of said precise position by storing a plurality of precise positions accumulated over a time period.

9. The method according to claim 8, wherein the accuracy of said precise position is increased to 10 centimeters.

10. The method according to claim 9, wherein the time period is a quarter of an hour.

11. The method according to claim 8, wherein the accuracy of said precise position is increased to 2 centimeters.

12. The method according to claim 11, wherein the time period is a half an hour.

13. The method according to claim 1, wherein the code measurements include code measurement noises, at a scale of one pass, of an order of tens of cycles.

14. The method according to claim 1, wherein, with respect to the phase ambiguities being removed during the determining of the carrier code shift combination value, the code measurements are utilized to determine a widelane ambiguity.

15. The method according to claim 14, wherein, with respect to the phase ambiguities being removed during the determining of the carrier code shift combination value, the widelane ambiguity is utilized to solve the narrowlane ambiguity.

16. A computer program product comprising non-transitory computer readable medium containing a computer program code for implementing geopositioning operations, by at least one radio navigation signal receiver of a reference network, using radio-navigation signals from a set of satellites of the reference network, each satellite of the set broadcasting at least a first radio-navigation signal on a first frequency and a second navigation signal on a second frequency distinct from the first frequency, the computer program code for implementing the geopositioning operations enabling the at least one radio navigation signal receiver to remove phase ambiguities, the computer program code executable by a processing unit to cause the processing unit to perform:

receiving, by the at least one radio navigation signal receiver, for each satellite of the set that is visible from a receiver, at least the said first radio-navigation signal;

performing, by the at least one radio navigation signal receiver, for each visible satellite, code measurements and phase measurements of the first radio-navigation signal received, said phase measurements presenting the phase ambiguities, the phase ambiguities including an ambiguity of an a priori unknown integer number of cycles;

receiving, by the at least one radio navigation signal receiver, a set of assistance data, wherein the set of assistance data comprises, for each satellite of the set of satellites, data sufficient for reconstructing a transmitter clock value associated with a carrier code shift combination, derived in a same manner across all the satellites and receivers of the reference network;

determining, by the at least one radio navigation signal receiver, for each satellite, a carrier code shift combination value from the code measurement and the phase measurement of the first radio-navigation signal, the phase ambiguities being removed as a result of the determining of the carrier code shift combination value;

determining, by the at least one radio navigation signal receiver, from said carrier code shift combination value the transmitter clock value associated with the carrier code shift combination, to obtain an unambiguous carrier code shift observable; and

utilizing, by the at least one radio navigation signal receiver, the unambiguous carrier code shift observables to determine a precise receiver position of the at least one radio navigation signal receiver.

17. A global navigation satellite system receiver configured to implement geopositioning operations using radio-navigation signals from a set of satellites of a reference network, each satellite of the set broadcasting at least a first radio-navigation signal on a first frequency and a second navigation signal on a second frequency distinct from the first frequency, the geopositioning operations enabling the global navigation satellite system receiver to remove phase ambiguities, the operations comprising:

receiving, by the global navigation satellite system receiver, for each satellite of the set that is visible from the global navigation satellite system receiver, at least the said first radio-navigation signal;

performing, by the global navigation satellite system receiver, for each visible satellite, the code measurements and the phase measurements of the first radio-navigation signal received, said phase measurements presenting the phase ambiguities, the phase ambiguities including an ambiguity of an a priori unknown integer number of cycles;

receiving, by the global navigation satellite system receiver, a set of assistance data, wherein the set of assistance data comprises, for each satellite of the set of satellites, data sufficient for reconstructing a transmitter clock value associated with a carrier code shift combination, derived in a same manner across for all the satellites and receivers of the reference network;

determining, by the global navigation satellite system receiver, for each satellite, a carrier code shift combination value from the code measurement and the phase measurement of the first radio-navigation signal, the phase ambiguities being removed as a result of the determining of the carrier code shift combination value;

determining, by the at least one radio navigation signal receiver, from said carrier code shift combination value the transmitter clock value associated with the carrier code shift combination, to obtain an unambiguous carrier code shift observable; and

utilizing, by the global navigation satellite system receiver, the unambiguous carrier code shift observables to determine a precise global navigation satellite system receiver position.