Patent ID: 6535163
Filing Date: 2003-03-18
Classification: G01S

Abstract:
A method for determining a location of a receiver, the method comprising the computer-implemented steps of:calculating a current value range for a delay value and a current value range for a modulation frequency value corresponding to each signal source from a set of signal sources that is overhead the receiver; calculating an estimate for the delay value and an estimate for the modulation frequency value corresponding to each signal source by using segments of increasing length of a sampled data that is associated with a received signal that is received at the receiver; updating the current value range for the delay value and the current value range for the modulation frequency value based on the estimate for the delay value and the estimate for the modulation frequency value; determining a current search range for the delay value and a current search range for the modulation frequency value; corresponding to each signal source from the set of signal sources, using the sampled data to calculate a set of magnitude calculations of I and Q correlation integrals for: a set of delay values from within the current search range for the delay value, wherein the current search range for the delay value includes delay values that surround the estimate of the delay value; and a set of modulation frequency values from within the current search range for the modulation frequency value, wherein the current search range for the modulation frequency value includes modulation frequency values that surround the estimate of the modulation frequency value; corresponding to each signal source from the set of signal sources, determining interpolated calculations of I and Q correlation integrals by interpolating the calculations of I and Q correlation integrals based on the set of magnitude calculations and a magnitude value corresponding to the estimate of the delay value and the estimate of modulation frequency value; and calculating the location of the receiver by using the interpolated calculations of I and Q correlation integrals for each signal source.