US 11,740,364 B1
System and method to reduce PPP filter convergence time using LEO frequency band signals
James Kilfeather, Covington, LA (US); and Samuel Phillip Pullen, Stanford, CA (US)
Assigned to Globalstar, Inc., Covington, LA (US)
Filed by Globalstar, Inc., Covington, LA (US)
Filed on Jan. 7, 2022, as Appl. No. 17/570,471.
Application 17/570,471 is a continuation of application No. 16/582,040, filed on Sep. 25, 2019, granted, now 11,226,416.
Claims priority of provisional application 62/904,243, filed on Sep. 23, 2019.
Claims priority of provisional application 62/752,701, filed on Oct. 30, 2018.
Claims priority of provisional application 62/736,269, filed on Sep. 25, 2018.
This patent is subject to a terminal disclaimer.
Int. Cl. G01S 19/31 (2010.01); G01S 19/32 (2010.01); G01S 19/42 (2010.01); G01S 19/25 (2010.01)
CPC G01S 19/31 (2013.01) [G01S 19/258 (2013.01); G01S 19/42 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A method of enhancing accuracy of a navigation system including a GNSS receiver, the method comprising the steps of:
(a) receiving navigation signals from at least (i) a first GNSS constellation, and (ii) a first LEO constellation;
(b) receiving augmentation data signals from at least one of (i) the first LEO constellation, (ii) a GEO constellation, or (iii) a terrestrial source, wherein the augmentation data includes at least one of (i) wide-area differential GNSS (WADGNSS) data, (ii) Precise Point Positioning (PPP) data, (iii) local-area differential GNSS (LADGNSS) data, or (iv) Real Time Kinematic (RTK) data;
(c) utilizing (1) WADGNSS and/or PPP data to confirm the integrity of (2) the LADGNSS data and/or RTK data, and if the integrity is confirmed, utilizing the LADGNSS data and/or RTK data to correct navigation signals and generate protection levels;
(d) creating at least one position estimate through implementation of a filter using as filter inputs successive readings of at least (i) pseudoranges and carrier-phase measurements from the GNSS constellation, and (ii) carrier-phase measurements from the LEO constellation;
(e) performing Receiver Autonomous Integrity Monitoring (RAIM) by:
(i) using as filter inputs satellite measurements from all satellites within a first set of satellites in order to produce a first filter output,
(ii) iteratively removing as filter inputs satellite measurements from a subset of satellites in the first set in order to produce parallel filter outputs, and
(iii) excluding satellite measurements whose inclusion in the filter inputs creates a parallel output significantly differing from the first filter output.