Method and apparatus for geolocating a wireless communications device
First Claim
1. A method for determining the location of a transmitting unit transmitting a signal, comprising:
- (a) transforming the signal received at a first site to a frequency domain representation comprising first component signals each having a frequency and a phase angle parameter and transforming the signal received at a second site to a frequency domain representation comprising second component signals each having a frequency and a phase angle parameter;
(b) operating in the frequency domain, determining a Hermitian product of first and second component signals having a same frequency parameter;
(c) operating in the frequency domain, determining a phase angle parameter of each Hermitian product determined at the step (b);
(d) determining a relationship between the phase angle parameter and the frequency parameter for a plurality of Hermitian products;
(e) determining a time difference of arrival of the signal from the relationship.(f) selecting a location estimate for the transmitting unit;
(g) determining a distance difference of arrival from the location estimate to the first and the second sites, the distance difference of arrival responsive to the time difference of arrival;
(h) determining an error in the location estimate in response to the distance difference of arrival value; and
(i) updating the location estimate in response to the error.
0 Assignments
0 Petitions
Accused Products
Abstract
The time difference of arrival for a signal received at two or more receiving sites as transmitted from a wireless communications device, is determined by a frequency domain technique. The constituent frequencies of the signals received at the two or more receiving sites are determined, including the phase, or a value representative of the phase, of each frequency component. The phase values for the same frequency are subtracted to yield a phase difference values as a function of frequency. The slope of the function represents the time difference of arrival for the wireless communications device signal as received at the two receiving sites. To determine the mobile location based on the determined time difference of arrival values, a seed or initial location is first assumed for the wireless communications device and the distance difference of arrival (the time difference of arrival multiplied by the speed of light) is calculated. The calculated time difference of arrival is then used to adjust the distance difference of arrival by continuously iterating the position of the wireless communications device until the calculated distance of arrival and the calculated time difference of arrival (as multiplied by the speed of light) are within a predetermined margin.
-
Citations
8 Claims
-
1. A method for determining the location of a transmitting unit transmitting a signal, comprising:
-
(a) transforming the signal received at a first site to a frequency domain representation comprising first component signals each having a frequency and a phase angle parameter and transforming the signal received at a second site to a frequency domain representation comprising second component signals each having a frequency and a phase angle parameter; (b) operating in the frequency domain, determining a Hermitian product of first and second component signals having a same frequency parameter; (c) operating in the frequency domain, determining a phase angle parameter of each Hermitian product determined at the step (b); (d) determining a relationship between the phase angle parameter and the frequency parameter for a plurality of Hermitian products; (e) determining a time difference of arrival of the signal from the relationship. (f) selecting a location estimate for the transmitting unit; (g) determining a distance difference of arrival from the location estimate to the first and the second sites, the distance difference of arrival responsive to the time difference of arrival; (h) determining an error in the location estimate in response to the distance difference of arrival value; and (i) updating the location estimate in response to the error. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
Specification