POST-PROCESSING GLOBAL NAVIGATION SATELLITE SYSTEM (GNSS) POSITION DATA USING MIRRORED GNSS DATA

• US 20200132860A1
• Filed: 05/01/2019
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Trimble Inc.
• Original Assignee: Trimble Inc.
• Inventors: DMITRIEVICH, BORISKIN ALEKSEY, GENNADIEVICH, KOZLOV DMITRY, VALERIANOVICH, LYOSKIN VICTOR
• Granted Patent: US 11,156,722 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/07 providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/10 providing dedicated supplementary positioning signals
• CPC Class Codes: G01S 19/40 Correcting position, velocity or attitude
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/426 by combining or switching between position solutions or signals derived from different modes of operation in a single system
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
• CPC Class Codes: G01S 19/52 Determining velocity

Abstract

A post-processing system providing forward processing (FP) of original GNSS raw data and alternative forward-backward processing (BP) of modified GNSS raw data and combining results of the FP and modified BP to enhance accuracy of position data derived from GNSS raw data. The post-processing system includes a GNSS processing engine, such as a real-time PVT engine, that processes GNSS raw data files as real time data streams equally for FP and BP. The backward processing is performed on a set of GNSS raw data that is mirrored from the original GNSS raw data. The modified BP uses the same algorithms of the PVT engine in a forward run but with the mirrored GNSS raw data to provide BP including position estimate with associated accuracy estimates for each data epoch. A forward/backward combiner combines results of the FP and the modified BP to provide final position data with enhanced precision.

Claims

1. A system for post-processing global navigation satellite system (GNSS) data to enhance position accuracy, comprising:

a processor;

memory storing a GNSS data file;

a first set of code executed by the processor to provide a position, velocity, and time (PVT) application, wherein the PVT application processes the GNSS data file with a forward run to generate a first forward run position file;

a second set of code executed by the processor to provide a mirror time application modifying the GNSS data file to generate a mirrored GNSS data file, wherein the PVT application processes the mirrored GNSS data file with a forward run to generate a second forward run position file; and

a third set of code executed by the processor to provide a combiner application combining the first and second forward run position files to generate a precise position file including position data with higher accuracy at one or more epochs than in only one of the first and second forward run position files.

2. The system of claim 1, wherein the GNSS data file includes a GNSS file from a base and a GNSS file from a rover.

3. The system of claim 1, wherein the GNSS data file and the mirrored GNSS data file are Receiver Independent Exchange Format (RINEX) files.

4. The system of claim 1, wherein the PVT application is a forward-only PVT application.

5. The system of claim 1, wherein the mirrored GNSS data file comprises measurement epochs of the GNSS data file in reverse order.

6. The system of claim 5, wherein the mirror time application modifies measurements read from the GNSS data file to form mirrored measurements in the mirrored GNSS data file including, for each of the reverse order measurement epochs, modifying range and phase by difference in calculated distance and modifying doppler by difference in calculated velocity.

7. The system of claim 5, wherein residuals in the GNSS data file at each of the measurement epochs match residuals in the mirrored GNSS data file at each of the reverse order measurement epochs.

8. The system of claim 7, wherein the mirror time application mirrors orbit data provided in the mirrored GNSS data file by modifying ephemeris in the GNSS data file such that a satellite associated with data in the GNSS data file is flying backwards based on its satellite positions.

9. A system for post-processing global navigation satellite system (GNSS) data to enhance position accuracy, comprising:

a position, velocity, and time (PVT) engine performing a forward run on a GNSS data file to generate a forward processing (FP) position file;

a mirrored GNSS data generator modifying the GNSS data file to generate a mirrored GNSS data file, wherein the PVT engine further operates to perform a forward run on the mirrored GNSS data file to generate a backward processing (BP) position file; and

a FP/BP combiner combining the FP and BP position files to generate a position file including position data at a plurality of epochs, wherein the mirrored GNSS data file comprises mirror measurements at each of the plurality of epochs in reverse order.

10. The system of claim 9, wherein the GNSS data file and the mirrored GNSS data file are Receiver Independent Exchange Format (RINEX) files and wherein the PVT engine is a real-time and forward-only PVT engine.

11. The system of claim 9, wherein the mirrored GNSS data generator modifies measurements read from the GNSS data file to form the mirror measurements in the mirrored GNSS data file including, for each of the reverse order measurement epochs, modifying range and phase by difference in calculated distance and modifying doppler by difference in calculated velocity.

12. The system of claim 9, wherein residuals in the GNSS data file at each of the measurement epochs correspond to residuals in the mirrored GNSS data file at each of the reverse order measurement epochs.

13. The system of claim 12, wherein the mirror time application mirrors orbit data provided in the mirrored GNSS data file by modifying ephemeris in the GNSS data file such that a satellite associated with data in the GNSS data file is flying backwards based on its satellite positions.

14. A method of post-processing global navigation satellite system (GNSS) data to enhance position accuracy, comprising:

generating a first forward run position file by performing forward processing (FP) of a GNSS data file, wherein the first forward run position file includes first position data at a plurality of epochs;

reading the GNSS data file to obtain measurements at the plurality of epochs;

reversing the plurality of epochs and modifying the GNSS data file including the measurements at the plurality of epochs to generate a mirrored GNSS data file;

generating a second forward run position file by performing the FP of the mirrored GNSS data file, wherein the second forward run position file includes second position data at the plurality of epochs; and

combining the first and second forward run position files to generate a final position file including position data based on the first and second position data at each of the plurality of epochs.

15. The method of claim 14, wherein the GNSS data file includes a GNSS file from a base and a GNSS file from a rover.

16. The method of claim 14, wherein the GNSS data file and the mirrored GNSS data file are Receiver Independent Exchange Format (RINEX) files.

17. The method of claim 14, wherein FP is performed by a computer running a forward-only PVT application.

18. The method of claim 14, wherein the modifying of the measurements includes, for each of the reverse order measurement epochs, modifying range and phase by difference in calculated distance and modifying doppler by difference in calculated velocity.

19. The method of claim 14, further comprising modifying residuals in the GNSS data file at each of the measurement epochs match so that residuals in the mirrored GNSS data file at each of the reverse order measurement epochs is the same as the residuals in the GNSS data file.

20. The method of claim 19, further including mirroring orbit data for inclusion in the mirrored GNSS data file by modifying ephemeris in the GNSS data file such that a satellite associated with data in the GNSS data file is flying backwards based on its satellite positions.