Method, apparatus, and system for determining a position of an object having a global navigation satellite system receiver by processing undifferenced data like carrier-phase measurements and external products like ionosphere data

Patent metadata

Field	Value
Publication number	US-9494693-B2
Application number	US-201114007647-A
Country	US
Kind code	B2
Filing date	Mar 25, 2011
Priority date	Mar 25, 2011
Publication date	Nov 15, 2016
Grant date	Nov 15, 2016

Abstract

A method for determining a position of an object having a Global Navigation Satellite System (GNSS) receiver comprises receiving signals that are transmitted by GNSS transmitters positioned on board satellites positioned in view of the object; updating service data in the object, the service data including satellite clock data, satellite orbit data, satellite delay code bias data relating to delay code biases of the GNSS transmitters, and ionospheric model data indicating a state of an ionosphere; determining, based on the ionospheric model data, ionospheric delay data indicating corrections relating to delays of the signals, the delays of the signals resulting from passage of the signals through the ionosphere, and reception of the signals by the GNSS receiver; and determining a position of the object based on the signals, the satellite clock data, the satellite orbit data, the satellite delay code bias data, and the determined ionospheric delay data.

First claim

The invention claimed is:

1. A method for determining a position of an object having a Global Navigation Satellite System (GNSS) receiver, the method comprising the steps of:
receiving signals by the GNSS receiver that are transmitted by GNSS transmitters (GNSS E1 to GNSS En ) positioned on board satellites (SAT 1 to SAT n ) that are positioned in view of the object;
updating service data in the object, the service data being provided by a GNSS service provider and including:
satellite clock data indicating internal clocks of the satellites (SAT 1 to SAT n );
satellite orbit data indicating positions of the satellites (SAT 1 to SAT n );
satellite delay code bias data relating to delay code biases of the GNSS transmitters (GNSS E1 to GNSS En ); and
ionospheric model data indicating a state of an ionosphere;

determining, based on the ionospheric model data, ionospheric delay data indicating corrections relating to delays of the signals, the delays of the signals resulting from a passage of the signals through the ionosphere between transmission of the signals from the GNSS transmitters (GNSS E1 to GNSS En ), and reception of the signals by the GNSS receiver (SUR GNSS );
obtaining code observation data from the signals, the code observation data relating to data transmitted with the signals and comprising code observables relating to data transmitted with the signals;
obtaining carrier-phase observation data from the signals, the carrier-phase observation data relating to carrier phases of the signals and comprising carrier-phase observables relating to the carrier phase of the signals; and
determining a position of the object based on the satellite clock data, the satellite orbit data, the satellite delay code bias data, the determined ionospheric delay data, the code observation data obtained from the signals, and the carrier-phase observation data obtained from the signals,
wherein all code observables and all carrier-phase observables involved in the step of determining the position of the object are processed in an undifferenced mode, and
wherein, in the step of determining the position of the object, at least one linear combination of observables that is not ionospheric free and additionally a linear combination of observables that is ionospheric free are processed.

2. The method according to claim 1 , further comprising at least one of the steps of:
determining an ionospheric delay of a code observable;
determining an ionospheric delay of a carrier-phase observable;
determining an ionospheric delay of a geometric-free combination of code observables; and
determining an ionospheric delay of a geometric-free combination of carrier-phase observables.

3. The method according to claim 1 , wherein the service data further comprises satellite-phase bias data relating to carrier-phase biases of the GNSS transmitters (GNSS E1 to GNSS En ), and
wherein the step of determining the position of the object further comprises a step of determining carrier-phase ambiguity data indicating for at least one signal a count of full cycles comprised in a phase difference between a carrier phase of the signal at a transmission timing and a carrier phase of the signal at a reception timing based on the carrier-phase observation data and the satellite-phase bias data.

4. The method according to claim 1 , wherein in the step of determining the position of the object, at least one recursive estimation process is executed.

5. The method according to claim 4 , wherein at each step of the at least one recursive estimation process state data, comprising at least one of the position of the object and carrier-phase ambiguity data, is estimated based on the signals, the satellite clock data, the satellite orbit data, the ionospheric delay data, and an estimate of the state data estimated at the previous step.

6. The method according to claim 1 , wherein the ionospheric model data comprises ionospheric model reliability data relating to a position-dependent reliability of the ionospheric model data, and wherein the step of determining the position of the object is further based on the ionospheric model reliability data.

7. The method according to claim 1 , wherein:
at least one fixed ground station serves as a central processing facility;
a plurality of fixed ground stations that each have a GNSS receiver serve as network stations;
the at least one central processing facility and the plurality of network stations form a network;
the service data is obtained by the network and transmitted to the object; and
obtaining the ionospheric model data comprises the steps of:
receiving at the network stations signals of at least two different frequencies transmitted by GNSS transmitters positioned aboard a plurality of satellites arranged in view of at least one of the network stations;
determining network ionospheric delay data indicating corrections relating to delays of the signals received at the network stations, the delays of the signals received at the network stations resulting from a passage of the signals received at the network stations through the ionosphere; and
determining the ionospheric model data from the network ionospheric delay data.

8. The method according to claim 7 , wherein determining the ionospheric model data further comprises the steps of:
expanding the number density of free electrons in the ionosphere into a plurality of functions; and
estimating electron content data indicating coefficients of the plurality of functions based on the network ionospheric delay data.

9. The method according to claim 7 , wherein geodetic data relating to at least one of internal clocks of the plurality of satellites, positions of the plurality of satellites, delay code biases of the GNSS transmitters aboard the plurality of satellites, and carrier-phase biases of the GNSS transmitters aboard the plurality of satellites, and ionospheric data relating to a state of the ionosphere are processed simultaneously by a first estimation process and a second estimation process, the first and second estimation processes having different processing speeds and interacting with each other.

10. The method according to claim 1 , wherein a satellite clock refresh rate, a satellite orbit data refresh rate, and an ionospheric model refresh rate, respectively, indicating a rate with which the satellite clock data is continuously updated at the object, a rate with which the satellite orbit data is continuously updated at the object, and a rate with which the ionospheric model data is continuously updated at the object, are chosen such that the satellite clock data refresh rate is larger than the satellite orbit data refresh rate and the satellite clock data refresh is larger than the ionospheric model data refresh rate.

11. An apparatus for determining a position, the apparatus comprising:
means for receiving signals which are transmitted by GNSS transmitters (GNSSE 1 to GNSSEn) on board a given number of satellites (SAT 1 to SATn) positioned in view of the apparatus;
means for updating service data, the service data being provided by a GNSS service provider and including:
satellite clock data indicating internal clocks of the satellites (SAT 1 to SAT n );
satellite orbit data indicating positions of the satellites (SAT 1 to SAT n );
satellite delay code bias data relating to delay code biases of the GNSS transmitters (GNSS E1 to GNSS En ); and
ionospheric model data indicating a state of an ionosphere;

means for determining, based on the ionospheric model data, ionospheric delay data indicating corrections relating to delays of the signals, the delays of the signals resulting from a passage of t

Assignees

• Hernández-Pajares Manuel
• JUAN ZORNOZA José Miguel
• Sanz Subirana Jaume
• Samson Jaron
• Tossaint Michel Mathias Maria
• ESA

Inventors

• Hernández-Pajares Manuel
• JUAN ZORNOZA José Miguel
• Sanz Subirana Jaume
• Samson Jaron
• Tossaint Michel Mathias Maria

Classifications

• G01S19/44 Primary

  Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method · CPC title

• G01S19/02

  Details of the space or ground control segments · CPC title

• G01S19/29 Primary

  carrier {including Doppler,} related {(G01S19/246 takes precedence)} · CPC title