GNSS signal processing methods and apparatus

• US 9,274,230 B2
• Filed: 09/12/2012
• Issued: 03/01/2016
• Est. Priority Date: 09/16/2011
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Artushkin, Igor, Boriskin, Alexey, Ivanov, Dmitry, Kozlov, Dmitry, Sunitsky, Evgeny, Zyryanov, Gleb
• Primary Examiner(s): Issing, Gregory C
• Application Number:
  US13/611,361
• Publication Number:
  US 20130141276A1
• Time in Patent Office: 1,266 Days
• US Class Current: 1/1
• CPC Class Codes: G01S 19/33 Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• 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

Abstract

Methods and apparatus are presented for determining position a GNSS rover antenna from single-frequency observations of GNSS signals collected at the antenna over multiple epochs and from correction data for at least one of the epochs. Coded raw data prepared from the single-frequency observations in a binary format are obtained and decoded to obtain decoded raw data. The decoded raw data are used to construct multiple epochs of measurement data of time, range and phase. Correction data are obtained for at least one of the epochs. The measurement data are processed with the correction data in a realtime kinematic positioning engine to obtain a position estimate for each of a plurality of epochs.

Claims

1. A method of determining a position of an antenna of a global navigation satellite system (GNSS) rover from single-frequency observations of GNSS signals collected at the antenna and from correction data, comprising:

obtaining, from a GNSS chipset associated with the antenna, coded raw data in a binary format, the coded raw data obtained from the single-frequency observations,

decoding, external to the GNSS chipset, the coded raw data to obtain decoded raw data, the decoded raw data including receiver clock offset data, measurement time data, pseudorange data, and Doppler data, wherein the measurement time data, the pseudorange data, and the Doppler data are not corrected to account for receiver clock offsets,

using the decoded raw data to construct a plurality of epochs of measurement data of time, range, and phase, the measurement data constructed by determining the receiver clock offsets using the receiver clock offset data, correcting the measurement time data, the pseudorange data, and the Doppler data to account for the receiver clock offsets, and using the corrected Doppler data to construct the phase,

obtaining correction data for at least one of the epochs from a source external to the GNSS chipset,

processing the measurement data with the correction data in a realtime kinematic positioning engine to obtain an estimate of the position of the antenna for each of the plurality of epochs.

2. The method of claim 1, wherein the single-frequency observations are at a GNSS L1 frequency.

3. The method of claim 1, wherein the GNSS chipset is part of a consumer-quality GNSS receiver.

4. The method of claim 3, wherein the consumer-quality GNSS receiver comprises at least one of:

a MobileMapper 10 GNSS receiver, a SiRF GNSS receiver chip, a Trimble Juno41 handheld having a Ublox chip, and a Ublox chip.

5. The method of claim 3, wherein the consumer-quality GNSS receiver has at least one of the following characteristics:

(a) narrow band RF front end filter, (b) L1 only, (c) raw data output, and (d) approximately 1 Hz data update rate.

6. The method of claim 1, wherein the correction data comprise one of:

RTK base station data, L-Band correction data, and SBAS correction data.

7. The method of claim 1, wherein decoding comprises correcting the pseudorange data to obtain the range.

8. The method of claim 1, wherein decoding comprises correcting the measurement time data to obtain the time.

9. The method of claim 1, wherein obtaining the estimate of the position for each of the plurality of epochs comprises determining a float ambiguity for each of the plurality of epochs.

10. The method of claim 1, wherein using the decoded raw data to construct the phase comprises restoring carrier phase for a time sample k as:

PHI(k)=PHI(k−

1)+D(k)

wherein PHI(k) is a carrier phase observable for a time sample k, PHI(k−

1) is a carrier phase observable for the previous time sample k−

1, and D(k) is a Doppler observable for the time sample k.

11. The method of claim 1, wherein processing the measurement data with the correction data in the realtime kinematic positioning engine to obtain the estimate of the position for each of the plurality of epochs occurs immediately following construction of the measurement data.

12. A computer program product comprising:

a non-transitory computer usable medium having computer readable instructions physically embodied therein, the computer readable instructions comprising the method of claim 1.

13. Apparatus for determining a position of an antenna of a global navigation satellite system (GNSS) rover from single-frequency observations of GNSS signals collected at the antenna and from correction data, comprising at least one processor with instructions enabling the at least one processor to:

a. obtain, from a GNSS chipset associated with the antenna, coded raw data in a binary format, the coded raw data obtained from the single-frequency observations,

b. decode the coded raw data to obtain decoded raw data, the decoded raw data including receiver clock offset data, measurement time data, pseudorange data, and Doppler data, wherein the measurement time data, the pseudorange data, and the Doppler data are not corrected to account for receiver clock offsets,

c. use the decoded data to construct a plurality of epochs of measurement data of time, range and phase, the measurement data constructed by determining the receiver clock offsets using the receiver clock offset data, correcting the measurement time data, the pseudorange data, and the Doppler data to account for the receiver clock offsets, and using the corrected Doppler data to construct the phase,

d. obtain correction data for at least one of the epochs from an external source,

e. process the measurement data with the correction data in a realtime kinematic positioning engine to obtain an estimate of the position of the antenna for each of the plurality of epochs.

14. The apparatus of claim 13, wherein the single-frequency observations are at a GNSS L-1 frequency.

15. The apparatus of claim 13, wherein the GNSS chipset is part of a consumer-quality GNSS receiver.

16. The apparatus of claim 15, wherein the consumer-quality GNSS receiver comprises at least one of:

a MobileMapper 10 GNSS receiver, a SiRF GNSS receiver chip, a Trimble Juno41 handheld having a Ublox chip, and a Ublox chip.

17. The apparatus of claim 15, wherein the consumer-quality GNSS receiver has at least one of the following characteristics:

(a) narrow band RF front end filter, (b) L1 only, (c) raw data output, and (d) approximately 1 Hz data update rate.

18. The apparatus of claim 13, wherein the correction data comprise one of:

RTK base station data, L-Band correction data, and SBAS correction data.

19. The apparatus of claim 13, wherein decoding comprises correcting the pseudorange data to obtain the range.

20. The apparatus of claim 13, wherein decoding comprises correcting the measurement time data to obtain the time.

21. The apparatus of claim 13, wherein obtaining the estimate of the position for each of the plurality of epochs comprises determining a float ambiguity for each of the plurality of epochs.

22. The apparatus of claim 13, wherein using the decoded raw data to construct the phase comprises restoring carrier phase for a time sample k as:

PHI(k)=PHI(k−

1)+D(k)

wherein PHI(k) is a carrier phase observable for a time sample k, PHI(k−

1) is a carrier phase observable for the previous time sample k−

1, and D(k) is a Doppler observable for the time sample k.