US 9,810,788 B2
Wide area positioning system
Arun Raghupathy, Bangalore (IN); Subramanian S. Meiyappan, San Jose, CA (US); and Thomas Wolf, Mountain View, CA (US)
Assigned to NextNav, LLC, Sunnyvale, CA (US)
Filed by NextNav, LLC, Sunnyvale, CA (US)
Filed on Apr. 26, 2015, as Appl. No. 14/696,457.
Application 14/696,457 is a continuation of application No. 13/296,067, filed on Nov. 14, 2011, granted, now 9,057,606.
Claims priority of provisional application 61/413,170, filed on Nov. 12, 2010.
Prior Publication US 2015/0226854 A1, Aug. 13, 2015
This patent is subject to a terminal disclaimer.
Int. Cl. G01S 19/06 (2010.01); G01S 5/02 (2010.01); G01S 5/14 (2006.01); G01S 19/10 (2010.01); G01S 19/46 (2010.01); G01C 5/06 (2006.01)
CPC G01S 19/06 (2013.01) [G01C 5/06 (2013.01); G01S 5/021 (2013.01); G01S 5/14 (2013.01); G01S 5/145 (2013.01); G01S 19/10 (2013.01); G01S 19/46 (2013.01)] 27 Claims
OG exemplary drawing
 
1. A method for estimating an altitude of a receiver, the method comprising:
identifying
(a) a measurement of pressure measured by a pressure sensor of the receiver at a location of the receiver,
(b) a measurement of temperature not measured at the location of the receiver,
(c) a first reference pressure determined for a reference altitude using (i) a first pressure measurement measured by a first atmospheric reference sensor at a first known reference location and (ii) a first altitude of the first known reference location, and
(d) a second reference pressure determined for the reference altitude using (i) a second pressure measurement measured by a second atmospheric reference sensor at a second known reference location and (ii) a second altitude of the second known reference location;
determining, using one or more processors, a reference pressure estimate by: (i) combining two or more reference pressures that include the first reference pressure and the second reference pressure using a weighted average approach in which the weighting for the first reference pressure is a function of distance between the first known reference location and a point of interest, and the weighting for the second reference pressure is a function of distance between the second known reference location and the point of interest, or (ii) generating a second order surface that best fits at least two reference pressures that include the first reference pressure and the second reference pressure, and using the second order surface to determine the reference pressure estimate; and
determining, using the one or more processors, an estimated altitude of the receiver using the measurement of pressure, the measurement of temperature, and the reference pressure estimate.