# US 10,871,578 B2 · Differential correction map for GNSS

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- Number: US 10,871,578 B2
- Document ID: US10871578B2
- Status: Granted
- Kind: B2
- Application number: 16/184,440
- Filed: 2018-11-08
- Published: 2020-01-23
- Granted: 2020-12-22
- Earliest claimed: 2018-06-21
- Assignees: iBiquity Digital Corporation
- Applicants: iBiquity Digital Corporation
- Inventors: Brian Kroeger; Paul J. Peyla; Steven L. Teig
- Web page: https://patentgrep.com/patent/US10871578B2

## CPC

- G01S 19/41: Differential correction, e.g. DGPS [differential GPS]
- G01S 19/07: providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
- G01S 19/071: {DGPS corrections}
- G01S 19/073: {involving a network of fixed stations}
- 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 method comprises generating for a Global Navigation Satellite System (GNSS) a differential correction map (DCM) representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM, the differential corrections being based on a reference station constellation of GNSS reference stations having respective locations spanning the geographical area, the GNSS reference stations including physical or virtual reference stations.

## Claims

### Claim 1

A method comprising:
accessing aggregated differential correction information from a database; and
generating, from the aggregated differential correction information, for a Global Navigation Satellite System (GNSS) a differential correction map (DCM) representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM, the differential corrections being based on a reference station constellation of GNSS reference stations having respective locations spanning the geographical area, the GNSS reference stations including physical or virtual reference stations.

### Claim 2 (depends on 1)

The method of claim 1, wherein the reference station constellation includes a virtual reference station constellation (VRSC) including virtual reference stations approximately uniformly spaced across the geographical area represented by the DCM.

### Claim 3 (depends on 2)

The method of claim 2, further comprising:
selecting the VRSC from a set of predetermined VRSCs,
wherein the generating includes generating the DCM for the selected predetermined VRSC.

### Claim 4 (depends on 3)

The method of claim 3, wherein the DCM includes:
GNSS time; and
a location of only one of the reference stations;
an identifier of the VRSC;
an identifier of each GNSS satellite in view of the geographical area represented by the DCM; and
the differential correction for each reference station for each frequency of each GNSS satellite in view.

### Claim 5 (depends on 1)

The method of claim 1, wherein the reference stations are non-uniformly spaced across the geographical area represented by the DCM.

### Claim 6 (depends on 1)

The method of claim 1, wherein the DCM includes an identifier of the DCM, GNSS time, the locations of one or more of the reference stations, and differential corrections for each reference station.

### Claim 7 (depends on 1)

The method of claim 1, wherein the DCM includes:
GNSS time;
locations of the reference stations;
an identifier of each GNSS satellite in view of the geographical area represented by the DCM; and
the differential correction for each reference station for each frequency of each GNSS satellite in view.

### Claim 8 (depends on 7)

The method of claim 7, wherein the DCM further includes a drift rate of the differential correction for each reference station for each frequency of each GNSS satellite in view.

### Claim 9 (depends on 1)

The method of claim 1, wherein the DCM includes an identifier of the DCM, GNSS time, the locations of one or more of the reference stations, and polynomial coefficients of a polynomial fit for the differential corrections for the reference stations.

### Claim 10 (depends on 1)

The method of claim 1, wherein the generating includes generating the DCM from a two-dimensional polynomial surface fit to the differential correction associated with each frequency and each GNSS satellite in view of the geographical area represented by the DCM.

### Claim 11 (depends on 10)

The method of claim 10, wherein the DCM includes:
GNSS time;
an origin of the two-dimensional polynomial surface;
an identifier of each of the GNSS satellites in view of the geographical area represented by the DCM; and
polynomial coefficients associated with the two-dimensional polynomial surface.

### Claim 12 (depends on 11)

The method of claim 11, wherein the DCM further includes a drift rate of each polynomial coefficient for each frequency of each GNSS satellite in view.

### Claim 13 (depends on 1)

The method of claim 1, further comprising transmitting the DCM over a broadcast coverage area via a radio signal.

### Claim 14 (depends on 1)

The method of claim 1, further comprising storing the DCM in a computer database accessible over a communication network.

### Claim 15 (depends on 1)

The method of claim 1, further comprising:
generating multiple DCMs based on multiple reference station constellations, and alternately transmitting the multiple DCMs.

### Claim 16 (depends on 1)

The method of claim 1, further comprising:
encrypting the DCM; and
transmitting the encrypted DCM via broadcast radio signal or over a communication network.

### Claim 17

A method comprising:
determining a virtual reference station constellation (VRSC) of virtual reference stations having respective locations spanning a geographical area;
accessing aggregated differential correction information from a database;
generating, from the aggregated differential correction information, for a Global Navigation Satellite System (GNSS) a differential correction map (DCM) based on the VRSC, the DCM representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM; and
transmitting a radio signal that conveys the DCM across the geographical area.

### Claim 18 (depends on 17)

The method of claim 17, wherein the VRSC includes four or more of the virtual reference stations.

### Claim 19 (depends on 18)

The method of claim 18, wherein the virtual reference stations are approximately uniformly spaced across the geographical area represented by the DCM.

### Claim 20 (depends on 18)

The method of claim 18, wherein the virtual reference stations are non-uniformly spaced across the geographical area represented by the DCM.

### Claim 21

An apparatus comprising:
memory; and
a processor coupled to the memory and configured to:
access aggregated differential correction information from a database; and
generate, from the aggregated differential correction information, for a Global Navigation Satellite System (GNSS) a differential correction map (DCM) representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM, the differential corrections being based on a reference station constellation of GNSS reference stations having respective locations spanning the geographical area, the GNSS reference stations including physical or virtual reference stations.

### Claim 22 (depends on 21)

The apparatus of claim 21, wherein the reference station constellation includes a virtual reference station constellation (VRSC) including virtual reference stations approximately uniformly spaced across the geographical area represented by the DCM.

### Claim 23 (depends on 22)

The apparatus of claim 22, wherein the processor is further configured to:
select the VRSC from a set of predetermined VRSCs,
wherein the processor is configured to generate by generating the DCM for the selected predetermined VRSC.

### Claim 24 (depends on 23)

The apparatus of claim 23, wherein the DCM includes:
GNSS time; and
a location of only one of the reference stations;
an identifier of the VRSC;
an identifier of each GNSS satellite in view of the geographical area represented by the DCM; and
the differential correction for each reference station for each frequency of each GNSS satellite in view.

### Claim 25 (depends on 21)

The apparatus of claim 21, wherein the reference stations are non-uniformly spaced across the geographical area represented by the DCM.

### Claim 26 (depends on 21)

The apparatus of claim 21, wherein the DCM includes:
GNSS time;
locations of the reference stations;
an identifier of each GNSS satellite in view within the geographical area represented by the DCM; and
the differential correction for each reference station for each frequency of each GNSS satellite in view.

### Claim 27 (depends on 21)

The apparatus of claim 21, wherein the processor is configured to generate by generating the DCM from a two-dimensional polynomial surface fit to the differential correction associated with each frequency and each GNSS satellite in view of the geographical area represented by the DCM.

### Claim 28 (depends on 27)

The apparatus of claim 27, wherein the DCM includes:
GNSS time;
an origin of the two-dimensional polynomial surface;
an identifier of each of the GNSS satellites in view of the geographical area represented by the DCM; and
polynomial coefficients associated with the two-dimensional polynomial surface.

### Claim 29 (depends on 21)

The apparatus of claim 21, wherein the processor is further configured to provide the DCM to a transmitter configured to transmit the DCM over a broadcast coverage area via a radio signal.

### Claim 30 (depends on 21)

The apparatus of claim 21, further comprising a network interface unit coupled to the memory and the processor and configured to communicate with a communication network, such that the DCM is accessible over the communication network.

### Claim 31 (depends on 21)

The apparatus of claim 21, further comprising:
a transmitter, wherein the processor is further configured to generate multiple DCMs based on multiple reference station constellations, and the transmitter is configured to alternately transmit the multiple DCMs.