# US 12,216,211 B2 · System and method for correcting satellite observations

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- Number: US 12,216,211 B2
- Document ID: US12216211B2
- Status: Granted
- Kind: B2
- Application number: 18/514,103
- Filed: 2023-11-20
- Published: 2024-03-14
- Granted: 2025-02-04
- Earliest claimed: 2021-12-10
- Assignees: Swift Navigation, Inc.
- Applicants: Swift Navigation, Inc.
- Inventors: Anthony Mark Cole; Fergus MacPherson Noble; James Tidd; Sébastien Carcanague
- Web page: https://patentgrep.com/patent/US12216211B2

## CPC

- G01S 19/071: {DGPS corrections}
- G01S 19/073: {involving a network of fixed stations}
- G01S 19/04: providing carrier phase data
- G01S 19/41: Differential correction, e.g. DGPS [differential GPS]
- G01S 19/44: Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A system or method for determining a satellite observation for a virtual reference station can include: determining a virtual reference station location, receiving a set of satellite observations at a reference station located at a reference station location, determining a first GNSS correction for the virtual reference station location and a second GNSS correction for the reference station location, and determining the satellite observation for the virtual reference station by combining the set of satellite observations, the first GNSS correction, and the second GNSS correction.

## Claims

### Claim 1

A method for determining a position of a mobile receiver comprising:
determining a virtual reference station location associated with a virtual reference station;
receiving satellite signals from a set of satellites and determining a set of GNSS satellite observations from the satellite signals at a reference station located at a reference station location, wherein each GNSS satellite observation of the set of GNSS satellite observations is associated with a satellite in-view of the reference station;
determining a first GNSS correction for the virtual reference station location and a second GNSS correction for the reference station location;
determining a second set of GNSS satellite observations for the virtual reference station by combining the set of GNSS satellite observations, the first GNSS correction, and the second GNSS correction by, for each GNSS satellite observation of the set of GNSS satellite observations:
computing a first difference between the first GNSS correction and a respective GNSS satellite observation; and
computing a second difference between the second GNSS correction and the first difference, wherein the respective GNSS satellite observation of the second set of GNSS satellite observations for the virtual reference station comprises the second difference;
receiving satellite signals from a second set of satellites and determining a second set of GNSS satellite observations at the mobile receiver; and
correcting the second set of GNSS satellite observations using the GNSS satellite observation for the virtual reference station, wherein the position of the mobile receiver is determined using the corrected second set of GNSS satellite observations.

### Claim 2 (depends on 1)

The method of claim 1, wherein determining the virtual reference station location comprises setting the virtual reference station location to an initial locality of the mobile receiver.

### Claim 3 (depends on 1)

The method of claim 1, further comprising updating the virtual reference station location to a second virtual reference station location when a distance between the virtual reference station and the position of the mobile receiver exceeds a threshold distance.

### Claim 4 (depends on 3)

The method of claim 3, wherein the threshold distance is 10 kilometers.

### Claim 5 (depends on 3)

The method of claim 3, wherein the second virtual reference station location comprises the position of the mobile receiver when the distance exceeds the threshold distance.

### Claim 6 (depends on 1)

The method of claim 1, wherein determining the position of the mobile receiver comprises:
determining a set of carrier phase ambiguity hypothesis for the second set of corrected GNSS satellite observations; and
selecting a carrier phase ambiguity of the set of carrier phase ambiguity hypotheses based on results of a hypothesis test comparing carrier phase ambiguities of the set of carrier phase ambiguity hypotheses.

### Claim 7 (depends on 6)

The method of claim 6, wherein the set of carrier phase ambiguity hypotheses comprises integer-valued carrier phase ambiguity hypotheses.

### Claim 8 (depends on 1)

The method of claim 1, further comprising
receiving satellite signals from a third set of satellites and determining a third set of GNSS satellite observations at a second reference station located at a second reference station location;
determining a third GNSS correction for the second reference station location; and
wherein determining the GNSS satellite observation for the virtual reference station comprises combining the set of GNSS satellite observations, the first GNSS correction, the second GNSS correction, the third set of GNSS satellite observations, and the third GNSS correction.

### Claim 9 (depends on 1)

The method of claim 1, wherein the first GNSS correction and the second GNSS correction comprises state space representation corrections, wherein the GNSS satellite observation for the virtual reference station comprises an observation space representation.