Systems and methods for high-integrity satellite positioning

1. A system for determining a position of a global navigation satellite system (GNSS) receiver, the system comprising:

a corrections generator comprising:

an observation monitor configured to receive a first set of satellite observations associated with a first set of satellites; and

a modelling engine configured to generate corrections based on the first set of satellite observations;

a validation engine configured to validate the corrections; and

a positioning engine comprising:

a second observation monitor configured to receive a second set of satellite observations, associated with a second set of satellites, measured by the GNSS receiver;

an ambiguity module configured to determine a carrier phase ambiguity associated with the second set of satellite observations based on the validated corrections;

an ambiguity validator configured to validate the carrier phase ambiguity; and

a positioning module configured to estimate the position of the GNSS receiver based on the second set of satellite observations and the carrier phase ambiguity.

2. The system of claim 1 , wherein the corrections engine is implemented on a cloud computing server.

3. The system of claim 1 , wherein the positioning engine runs on a computing system collocated with the GNSS receiver.

4. The system of claim 1 , wherein the ambiguity module comprises:

a float filter configured to determine a real-valued carrier phase ambiguity estimate; and

an integer fixing module configured to determine an integer-valued carrier phase ambiguity estimate based on the real-valued carrier phase ambiguity estimate.

5. The system of claim 1 , wherein the ambiguity validator is configured to validate the carrier phase ambiguity using a multi-step validation, wherein an integrity of the estimated position depends on which step of the multi-step validation the carrier phase ambiguity is validated to.

6. The system of claim 1 , wherein the observation monitor is further configured to receive a third set of satellite observations, wherein the validation engine validates the corrections based on a comparison between a residual determined by correcting the third set of satellite observations using the corrections and a threshold.

7. The system of claim 1 , wherein the positioning engine further comprises a velocity module configured to determine a velocity of the GNSS receiver using differenced carrier phase measurements from the second set of satellite observations.

8. The system of claim 1 , further comprising:

an inertial measurement sensor, collocated with the GNSS receiver, configured to measure at least one of accelerometer or gyroscope data; and

a fusion filter configured to fuse the position estimated by the positioning module and the at least one of accelerometer or gyroscope data to determine a fused position estimate for the GNSS receiver.

9. A method comprising:

receiving a first set of satellite observations associated with at least one satellite constellation, wherein each satellite observation of the first set of satellite observations is measured at a reference station;

determining corrections based on the first set of satellite observations, wherein determining the corrections comprises:

estimating an atmospheric delay at each reference station;

generating a global model of an atmosphere based on the atmospheric delay at each reference station; and

generating the corrections based on the global model;

receiving a second set of satellite observations associated with at least one satellite constellation;

determining residuals between the second set of satellite observations and the corrections; and

validating the corrections when the residuals are less than an integrity bounded threshold;

wherein a positioning engine is configured to determine a receiver position from a third set of satellite observations using the validated corrections, wherein the receiver position comprises an integrity risk of at most 10 −4 per hour.

10. The method of claim 9 , wherein the atmospheric delay at each reference station is determined using a precise point positioning filter.

11. The method of claim 9 , wherein the global model is updated using a gaussian process.

12. The method of claim 9 , wherein the corrections are further generated based on a orbit, bias, and clock information associated with satellites of the at least one satellite constellation.

13. The method of claim 9 , further comprising comparing residuals and thresholds for a plurality of linear combinations of satellite frequencies or satellite signals to determine whether a failure to validate the corrections is associated with a satellite correction or an atmospheric correction.

14. The method of claim 9 , wherein the first set of satellite observations are received by and the corrections are determined by a cloud computing server.

15. The method of claim 9 , further comprising detecting drift over time in the corrections that impacts a receiver velocity estimate.

16. The method of claim 15 , wherein detecting the drift comprises differencing the residuals with residuals determined from a different time window to determine a differenced residual.

17. The method of claim 9 , further comprising:

monitoring at least one of the first or second set of satellite observations for a predetermined event; and

when the predetermined event is detected, mitigating the effect of the predetermined event.

18. The method of claim 9 , wherein the positioning engine performs a CRC check on the validated corrections, wherein the positioning engine uses the validated corrections when the validated corrections pass the CRC check.

19. A system for determining a position of a global navigation satellite system (GNSS) receiver, the system comprising:

a corrections generator comprising:

an observation monitor configured to receive a first set of satellite observations associated with a first set of satellites and to receive a second set of satellite observations associated with a second set of satellites; and

a modelling engine configured to generate corrections based on the first set of satellite observations;

a validation engine configured to validate the corrections based on a comparison between a residual determined by correcting the second set of satellite observations using the corrections and a threshold; and

a positioning engine comprising:

a second observation monitor configured to receive a third set of satellite observations, associated with a third set of satellites, measured by the GNSS receiver;

an ambiguity module configured to determine a carrier phase ambiguity associated with the third set of satellite observations based on the validated corrections; and

a positioning module configured to estimate the position of the GNSS receiver based on the third set of satellite observations and the carrier phase ambiguity.

20. The system of claim 19 , wherein the corrections engine is implemented on a cloud computing server.

21. The system of claim 19 , wherein the positioning engine further comprises a velocity module configured to determine a velocity of the GNSS receiver using differenced carrier phase measurements from the second set of satellite observations.

22. The system of claim 19 , wherein the positioning engine further comprises an ambiguity validator configured to validate the carrier phase ambiguity using a multi-step validation, wherein an integrity of the estimated position depends on which step of the multi-step validation the carrier phase ambiguity is validated to.

23. The system of claim 19 , wherein the ambiguity module comprises:

a float filter configured to determine a real-valued carrier phase ambiguity estimate; and

an integer fixing module configured to determine an integer-valued carrier phase ambiguity estimate based on the real-valued carrier phase ambiguity estimate.