Patent ID: 8208939
Filing Date: 2012-06-26
Classification: G01S

Abstract:
1. A wireless location system comprising: at least one wireless transmitter unit to be located by said wireless location system, wherein the at least one wireless transmitter unit transmits two wireless signals having a known time relationship and having different bandwidths, wherein the two wireless signals comprise an ultra wide band (UWB) signal and a narrower band signal, and wherein the UWB signal and the narrower band signal are both transmitted with a known time relationship between the UWB signal and the narrower band signal; a plurality of receivers, wherein a first receiver receives and processes a first of the two wireless signals and estimates a time to arrive (TOA) of the first wireless signal, and a second receiver receives and processes a second of the two wireless signals and estimates a TOA of the second wireless signal at the second receiver, said second receiver selecting an earliest TOA of said received signals, wherein the plurality of receivers is time synchronized based on a common timing signal, and wherein at least one receiver of the plurality of receivers comprises: a location server coupled to each of the plurality of receivers, the location server receiving the TOA of the first wireless signal from the first receiver and the selected TOA of the second wireless signal from the second receiver, the location server calculating a time difference of arrival (TDOA) of the two wireless signals and estimating a position of the at least one wireless transmitter unit based on the TDOA.