Systems and methods for selecting atmospheric data of reference nodes for use in computing the altitude of a receiver

Patent metadata

Field	Value
Publication number	US-2016356875-A1
Application number	US-201615238302-A
Country	US
Kind code	A1
Filing date	Aug 16, 2016
Priority date	Sep 4, 2015
Publication date	Dec 8, 2016
Grant date	—

Abstract

Using atmospheric data from one or more reference nodes to estimate an altitude of a receiver. Assistance data associated with a set of reference nodes within a region is identified, and the assistance data is used to identify atmospheric reference data associated with a subset of selected reference nodes. An estimate of the receiver's altitude is generated using the atmospheric reference data from the subset of reference nodes.

First claim

1 . A method for using atmospheric data from one or more reference nodes to estimate an altitude of a receiver, the method comprising:
identifying assistance data associated with a set of reference nodes within a region; selecting, using the assistance data, a subset of reference nodes from the set of reference nodes; identifying atmospheric reference data associated with the subset of reference nodes; and generating an estimate of the receiver's altitude using the atmospheric reference data associated with the subset of reference nodes, wherein the estimate of the receiver's altitude is generated without using atmospheric reference data associated with the reference nodes in the set that are not in the subset.

2 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
identifying, for each of the reference nodes in the set, a parameter associated with that reference node; selecting, as the only members of the subset, the reference nodes within the set that are associated with a parameter that satisfies a threshold criterion.

3 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
generating an initial position estimate of the receiver; determining, for each of the reference nodes in the set, a distance between that reference node and the initial position estimate of the receiver; and selecting, as the only member of the subset, the reference node that is closest to the initial position estimate of the receiver.

4 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
generating an initial position estimate of the receiver; determining, for each of the reference nodes in the set, a distance between that reference node and the initial position estimate of the receiver; and selecting, as the only members of the subset, the reference nodes that are within an identified maximum distance from the initial position estimate of the receiver.

5 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
identifying, from the assistance data, a temperature measured by each of the reference nodes in the set; and selecting, as the only member of the subset, the reference node that measured the lowest temperature.

6 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
identifying, from the assistance data, a temperature measured by each of the reference nodes in the set; and selecting, as the only member of the subset, the reference node that measured the closest temperature to a temperature measured by the receiver.

7 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
selecting, as the only members of the subset, the reference nodes within the set that each measured a temperature below a threshold temperature value, and that are located within a range of vertical distances.

8 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
selecting, as the only members of the subset, the reference nodes within the set that each measured a temperature that is within an identified numerical range.

9 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
selecting, as the only members of the subset, the reference nodes within the set that are each associated with a reference pressure that is within an identified numerical range.

10 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
selecting, as the only members of the subset, the reference nodes within the set that each measured a pressure that is within an identified numerical range.

11 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
measuring a temperature at the receiver; and selecting, as the only members of the subset, the reference nodes within the set that each measured a temperature that is within an identified amount of temperature from the temperature measured at the receiver.

12 . The method of claim 1 , wherein selecting a subset of reference nodes comprises:
measuring a pressure at the receiver; and selecting, as the only members of the subset, the reference nodes within the set that each measured a pressure that is within an identified amount of pressure from the pressure measured at the receiver.

13 . The method of claim 1 , wherein generating the estimate of the receiver's altitude comprises:
identifying reference pressures from the atmospheric reference data associated with the subset of reference nodes; generating an average of the reference pressures; and using the average to generate the estimate of the receiver's altitude.

14 . The method of claim 13 , wherein the average of the reference pressures is a weighted average of the reference pressures, and wherein generating the estimate of the receiver's altitude comprises:
generating, for each of the identified reference pressures, a weight that is inversely proportional to the line-of-sight distance between an initial estimate of the receiver's position and the reference node with which that reference pressure is associated; and using each of the generated weights to generate the weighted average of the reference pressures.

15 . The method of claim 13 , wherein the average of the reference pressures is a weighted average of the reference pressures, wherein generating the estimate of the receiver's altitude comprises:
generating, for each of the identified reference pressures, a weight that is inversely proportional to a temperature difference between a temperature measured at the receiver and a temperature measured at the reference node with which that reference pressure is associated; and using each of the generated weights to generate the average of the reference pressure.

16 . The method of claim 1 , wherein the subset of reference nodes includes each reference node in the set of reference nodes.

17 . One or more non-transitory machine-readable media embodying program instructions adapted to be executed to implement the method of claim 1 .

18 . A system for generating an estimate of a receiver's altitude, the system comprising:
a receiver with one or more atmospheric sensors operable to generate local atmospheric data; a network of a reference nodes operable to generate atmospheric reference data; and one or more modules operable to:
identify a subset of the atmospheric reference data generated by a corresponding subset of reference nodes, and
generate an estimate of the receiver's altitude using the atmospheric data and the subset of atmospheric reference data.

19 . The system of claim 18 , wherein the atmospheric data includes data that specifies a pressure and a temperature measured by the receiver, and the atmospheric reference data includes data that specifies computed reference pressures of the reference nodes.

Assignees

• Nextnav Llc

Inventors

• Wolf Thomas
• Dormody Michael

Classifications

• G01S19/45

  by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement · CPC title

• G01C5/06 Primary

  by using barometric means · CPC title

• G01S5/0236 Primary

  Assistance data, e.g. base station almanac · CPC title