Patent ID: 9716980
Date: 2017-07-25
CPC Classifications: G01S,H04W

Claim:
1. A method, comprising: initiating transmission of a first radio frequency (RF) pulse and a first acoustic pulse from a first beacon of a plurality of beacons, wherein the first RF pulse includes information about a first location of the first beacon, a first duration of the first RF pulse being shorter than a second duration of the first acoustic pulse, and the first acoustic pulse of the first beacon having a first acoustic cone of propagation, wherein the first acoustic pulse is detectable by a listening device of the system only within the first acoustic cone of propagation, wherein the first RF pulse and the first acoustic pulse are usable by the listening device to at least partially determine a first distance of the listening device from the first beacon; disabling further transmissions by the first beacon until all other beacons from the plurality of beacons have transmitted their respective RF pulses; identifying a second beacon, from the plurality of beacons, that has a second acoustic cone of propagation that does not overlap with the first acoustic cone of propagation; initiating transmission of a second RF pulse and a second acoustic pulse from the second beacon after the first duration of the first RF pulse but partially coinciding with the second duration of the first acoustic pulse, wherein the second RF pulse includes information about a second location of the second beacon, and the first acoustic pulse and the second acoustic pulse have a same acoustic frequency, wherein the second RF pulse and the second acoustic pulse are usable by the listening device to at least partially determine a second distance of the listening device from the second beacon; identifying a third beacon, from the plurality of beacons, that has a third acoustic cone of propagation that at least partially overlaps with the first acoustic cone of propagation; and configuring the third beacon not to transmit a third acoustic pulse until after a maximum time of flight of the first acoustic pulse, wherein the maximum time of flight of the first acoustic pulse is a longest duration that the first acoustic pulse is detectable by the listening device anywhere in the system, wherein the listening device determines its position within a signal propagation area of the plurality of beacons based at least in part on the first distance and the second distance.