Navigation and integrity monitoring

Patent metadata

Field	Value
Publication number	US-2016178752-A1
Application number	US-201414908878-A
Country	US
Kind code	A1
Filing date	Aug 1, 2014
Priority date	Aug 1, 2013
Publication date	Jun 23, 2016
Grant date	—

Abstract

A method and apparatus for signal weighting for satellite navigation systems is described. The method comprises (i) receiving secure and open service signals from at least one satellite navigation system, (ii) for received signals, determining a pseudo-range, and (iii) associating a statistical weighting to each pseudo-range, said weighting comprising a consideration of whether the signal is an open signal or a secure signal.

First claim

1 . A method for signal weighting for satellite navigation systems, comprising (i) receiving secure and open service signals from at least one satellite navigation system, (ii) for received signals, determining a pseudo-range, and (iii) associating a statistical weighting to each pseudo-range, said weighting comprising a consideration of whether the signal is an open signal or a secure signal.

2 . A method according to claim 1 , wherein the statistical weighting applied to a secure service signal is greater than that applied to an open service signal.

3 . A method according to claim 1 , wherein the weighting is further determined according to at least one predetermined rule.

4 . A method according to claim 3 , wherein the predetermined rule comprises a determination of which satellite constellation the signals are originating from.

5 . A method according to claim 3 , wherein the predetermined rule comprises screening the received signals to determine a signal quality to influence the weighting.

6 . A method according to claim 3 , wherein the predetermined rule comprises generating a confidence level from an authentication check to influence the weighting.

7 . A method according to claim 1 , wherein an acquisition step provides correlation between the received signals and candidate signals, which correlation is then compared to a predetermined threshold to influence the weighting.

8 . A method according to claim 1 , further comprising applying integrity monitoring to each pseudo-range in dependence on the associated statistical weighting of that pseudo-range.

9 . A method according to claim 8 , wherein the integrity monitoring comprises a Receiver Autonomous Integrity Monitoring (RAIM) step.

10 . A method according to claim 9 , wherein pseudo-ranges below a predetermined threshold weighting are excluded from the RAIM step.

11 . A method according to claim 9 , wherein the RAIM step is split into at least two tiers, with the first tier RAIM step being applied to previously determined secure pseudo-ranges, the output of which is then input to a second tier RAIM step which also receives the previously determined open pseudo-ranges, the second tier RAIM step then processing the inputs for fault detection and/or inclusion.

12 . Apparatus for satellite navigation systems, comprising a processing unit arranged to receive secure and open service signals from the satellite navigation systems, an analogue to digital converter capable of converting the received signals to digital signals, an acquisition module arranged to perform acquisition of the signals and a weighting module arranged to apply a statistical weighting to the signals received, said weighting comprising a consideration of whether the signal is an open signal or a secure signal.

13 . Apparatus for satellite navigation systems, comprising a processing unit arranged to receive secure and open service signals from the satellite navigation systems, an analogue to digital converter capable of converting the received signals to digital signals, an acquisition module arranged to perform acquisition of the signals and a weighting module arranged to apply a statistical weighting to the signals received, said weighting comprising a consideration of whether the signal is an open signal or a secure signal, wherein the processing unit is adapted to carry out the method of claim 1 .

14 . Apparatus according to claim 12 , further comprising a cryptographic module, arranged to support the acquisition module in acquiring the secure signals received.

15 . Apparatus according to claim 14 , further comprising a screening module adapted to determine the signal strength and quality of the received secure and open signals.

16 . Apparatus according to claim 15 , further comprising an authentication module, arranged to validate the source of the received signal secure and open signals.

17 . Apparatus according to claim 12 , further comprising a Receiver Autonomous Integrity Monitoring (RAIM) module, arranged to carry out RAIM functions.

18 . Apparatus according to claim 17 , further comprising a navigation module, arranged to determine position navigation and time data from the signals received.

19 . (canceled)

20 . A method for signal weighting of satellite navigation systems, the method comprising (i) receiving signals from at least one satellite navigation system, (ii) for received signals, determining a pseudo-range, and (iii) associating a statistical weighting to each pseudo-range, said weighting comprising a consideration of the relative trustworthiness of a source of the received signals.

21 . (canceled)

22 . Apparatus for satellite navigation systems, comprising a processing unit arranged to receive open RF signals, and comprising an analogue to digital converter capable of converting the RF signals to digital signals, an acquisition module, arranged to perform acquisition of the signals and a weighting module arranged to apply a statistical weighting to the signals received, said weighting comprising a consideration of the trustworthiness of a source of the received signals relative to one or more different sources.

23 . (canceled)

Assignees

• Qinetiq Ltd

Inventors

• Davies Nigel Clement
• Evans Thomas Andrew
• Bowden Richard Edward

Classifications

• G01S19/20 Primary

  Integrity monitoring, fault detection or fault isolation of space segment · CPC title

• G01S19/426

  by combining or switching between position solutions or signals derived from different modes of operation in a single system · CPC title

• G01S19/425

  by combining or switching between signals derived from different satellite radio beacon positioning systems · CPC title

• G01S19/24

  Acquisition or tracking {or demodulation} of signals transmitted by the system {(synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073)} · CPC title

• G01S19/42

  Determining position · CPC title