Patent ID: 6683569
Filing Date: 2004-01-27
Classification: G01S

Abstract:
A method of determining the time of arrival of an incident signal transmitted utilizing a code word, wherein the transmitted incident signal is interspersed with noise and diffracted and reflected signals of said incident signal, which are collectively defined as a combined signal, said method comprising:generating an autocorrelation of the incident signal; approximating the autocorrelation; receiving said combined signal; using the code word to apply a correlation function to the received combined signal to produce a correlation; creating a model of the correlation by superimposing a plurality of autocorrelation approximations, each of said approximations having a shape similar to that of the others but having variable amplitude and phase characteristics; using a multipath mitigation algorithm to compare the difference between the model of the correlation and the correlation to determine whether the model of the correlation and the correlation are similar with respect to amplitude and phase within a predetermined error bound; modifying the model of the correlation with respect to amplitude and phase if it is not similar to the correlation within the predetermined error bound; selecting from the plurality of superimposed autocorrelation approximations the approximation that corresponds to the incident signal if the resultant of the comparison between the model of the correlation and the correlation is within the predetermined error bound; and providing the time of arrival corresponding to the incident signal based on the selected autocorrelation approximation.