Combined cycle slip indicators for regionally augmented GNSS

Patent metadata

Field	Value
Publication number	US-9651667-B2
Application number	US-201213536912-A
Country	US
Kind code	B2
Filing date	Jun 28, 2012
Priority date	Jun 22, 2007
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

Methods and apparatus for determining a precise position of a rover located within a region are presented using rover observations comprising code observations and carrier-phase observations of GNSS signals on at least two carrier frequencies over multiple epochs. Correction data is received for each of the epochs at least one code bias per satellite. Synthetic reference data is generated for each of the epochs from the correction data for a synthetic station location. A determination is made for each epoch whether a cycle slip has occurred. Upon determining that a cycle slip has occurred, values of any variables of a set of state variables which are affected by the cycle slip are reset. Each epoch of rover observations and correction data is used to estimate updated values for the set of state variables including a set of ambiguities and coordinates of a precise rover position.

First claim

What is claimed is:

1. A method of determining, using a processor, a position of a rover, the method comprising:
obtaining rover observations comprising code observations and carrier-phase observations of GNSS signals on at least two carrier frequencies over multiple epochs;
receiving correction data comprising for each of the epochs at least one code bias per satellite, the code bias comprising at least one of: (i) a fixed-nature MW bias per satellite or (ii) values from which a fixed-nature MW bias per satellite is derivable, the correction data further comprising at least one of: (iii) an ionospheric delay per satellite for each of multiple regional network stations, (iv) non-ionospheric corrections, or (v) information on the corrections continuity for one or more correction components;
applying the correction data to the rover observations using one of (i) creating synthetic reference data for each of the epochs from the correction data for a synthetic station location or (ii) directly correcting the rover observations;
determining for each epoch whether an ionospheric cycle slip has occurred in at least one of (i) the rover observations or (ii) observations at the regional network stations used to prepare the correction data;
upon determining that an ionospheric cycle slip has occurred, resetting values of state variables affected by the ionospheric cycle slip and retaining values of state variables not affected by the ionospheric cycle slip; and
estimating updated values for a set of state variables using each epoch of the rover observations and the correction data, the set of state variables including the state variables affected by the ionospheric cycle slip and the state variables not affected by the ionospheric cycle slip.

2. The method of claim 1 , wherein the correction data comprises at least one ionospheric cycle slip indicator per satellite per regional network station, and wherein determining whether an ionospheric cycle slip has occurred comprises monitoring the ionospheric cycle slip indicators to determine an identity of at least one satellite-station pair for which an ionospheric cycle slip has occurred.

3. The method of claim 1 , wherein estimating updated values for the set of state variables comprises applying a factorized array of recursive filters, the factorized array of recursive filters comprising a code-carrier filter bank using a Melbourne-Wuebbena code-carrier combination, an ionospheric filter bank using an ionospheric carrier combination, and a geometry filter using an ionospheric-free carrier combination.

4. The method of claim 3 , wherein the correction data comprises at least one ionospheric cycle slip indicator per satellite, wherein determining that an ionospheric cycle slip has occurred comprises monitoring the ionospheric cycle slip indicators to identify an ionospheric cycle slip as to a specific satellite, and wherein resetting values of the state variables affected by the ionospheric cycle slip comprises resetting a value of an ionospheric ambiguity state for the specific satellite in the ionospheric filter bank.

5. The method of claim 1 , wherein estimating updated values for the set of state variables comprises applying a filter.

6. The method of claim 5 , wherein the correction data comprises at least one ionospheric cycle slip indicator per satellite, wherein determining that an ionospheric cycle slip has occurred comprises monitoring the ionospheric cycle slip indicators to identify an ionospheric cycle slip as to a specific satellite, and wherein resetting values of the state variables affected by the ionospheric cycle slip comprises resetting a value of an ionospheric ambiguity state for the specific satellite in the filter.

7. An apparatus for determining a position of a rover using rover observations and correction data, the rover observations comprising code observations and carrier-phase observations of GNSS signals on at least two carrier frequencies over multiple epochs, the correction data comprising for each of the epochs at least one code bias per satellite, the code bias comprising at least one of: (i) a fixed-nature MW bias per satellite or (ii) values from which a fixed-nature MW bias per satellite is derivable, the correction data further comprising at least one of: (iii) an ionospheric delay per satellite for each of multiple regional network stations, or (iv) non-ionospheric corrections, the apparatus comprising:
a synthetic reference station (SRS) module operative to create synthetic reference data for each of the epochs from the correction data for a synthetic station location;
a cycle slip determination module operative to determine for each epoch whether an ionospheric cycle slip has occurred in at least one of (i) the rover observations or (ii) observations at the regional network stations used to prepare the correction data;
a resetting module operative upon determining that an ionospheric cycle slip has occurred to reset values of state variables affected by the ionospheric cycle slip and retaining values of state variables not affected by the ionospheric cycle slip; and
an estimator module operative to estimate updated values for a set of state variables using each epoch of the rover observations and the correction data, the set of state variables including the state variables affected by the ionospheric cycle slip and the state variables not affected by the ionospheric cycle slip.

8. The apparatus of claim 7 , wherein the correction data comprises at least one ionospheric cycle slip indicator per satellite per regional network station, and wherein the cycle slip determination module is operative to monitor the ionospheric cycle slip indicators to determine an identity of at least one satellite-station pair for which an ionospheric cycle slip has occurred.

9. The apparatus of claim 7 , wherein the estimator module comprises a factorized array of recursive filters, the factorized array of recursive filters comprising a code-carrier filter bank using a Melbourne-Wuebbena code-carrier combination, an ionospheric filter bank using an ionospheric carrier combination, and a geometry filter using an ionospheric-free carrier combination.

10. The apparatus of claim 9 , wherein resetting values of the state variables affected by the ionospheric cycle slip comprises resetting a value of an ionospheric ambiguity state for the specific satellite in the ionospheric filter bank.

11. The apparatus of claim 7 , wherein the estimator module comprises a filter.

12. The apparatus of claim 11 , wherein resetting values of the state variables affected by the ionospheric cycle slip comprises resetting a value of an ionospheric ambiguity state for the specific satellite in the filter.

13. A method of determining, using a processor, a position of a rover, the method comprising:
obtaining rover observations comprising code observations and carrier-phase observations of GNSS signals on at least two carrier frequencies over multiple epochs;
receiving correction data comprising for each of the epochs at least one code bias per satellite, the code bias comprising at least one of: (i) a fixed-nature MW bias per satellite or (ii) values from which a fixed-nature MW bias per satellite is derivable, the correction data further comprising at least one of: (iii) an ionospheric delay per satellite for each of multiple regional network stations or (iv) non-ionospheric corrections;
applying the correction data to the rover observations using one of (i) creating synthetic reference data for each of the epochs from the correction data for a synthetic station location, or (ii) directly correcting the rover observations;
determinin

Assignees

• Leandro Rodrigo
• Talbot Nicholas Charles
• Trimble Inc

Inventors

• Leandro Rodrigo
• Talbot Nicholas Charles

Classifications

• G01S19/11 Primary

  wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters · CPC title

• G01S19/04

  providing carrier phase data · CPC title

• G01S19/20

  Integrity monitoring, fault detection or fault isolation of space segment · CPC title

• G01S19/43

  using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry · CPC title

• G01S19/44

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