US 12,262,284 B2
Wireless location system
Israel Amir, Princeton, NJ (US)
Assigned to CenTrak, Inc., Newtown, PA (US)
Filed by CenTrak, Inc., Newtown, PA (US)
Filed on Dec. 29, 2022, as Appl. No. 18/090,512.
Application 18/090,512 is a continuation of application No. 17/178,888, filed on Feb. 18, 2021, granted, now 11,570,580.
Application 18/090,512 is a continuation of application No. 16/775,880, filed on Jan. 29, 2020, granted, now 10,966,056, issued on Mar. 30, 2021.
Prior Publication US 2023/0144156 A1, May 11, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H04W 4/029 (2018.01); G01S 5/02 (2010.01); G01S 5/14 (2006.01); H04W 4/02 (2018.01); H04W 4/33 (2018.01); H04W 4/80 (2018.01); H04W 64/00 (2009.01)
CPC H04W 4/029 (2018.02) [G01S 5/0252 (2013.01); G01S 5/14 (2013.01); H04W 4/023 (2013.01); H04W 4/33 (2018.02); H04W 4/80 (2018.02); H04W 64/003 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method comprising:
receiving by a mobile device, at a first time t1, a wireless electromagnetic signal, the wireless electromagnetic signal comprising a first identifier that identifies a first beacon that transmitted the wireless electromagnetic signal;
receiving by the mobile device, at a second time t2, t2>t1, an ultrasound signal lacking an identification of the source of the ultrasound signal;
comparing time difference of arrival (TDOA) t2−t1 to a maximum TDOA; and
estimating a location of the mobile device, wherein the estimating is based on the TDOA only when the TDOA is less than or equal to the maximum TDOA;
wherein the first beacon belongs to a plurality of beacons that transmit wireless electromagnetic signals and ultrasound signals, and wherein the maximum TDOA is based on the transmitted power of one or more of the ultrasound signals.