Patent ID: 6683923
Filing Date: 2004-01-27
Classification: G01S,H04B

Abstract:
A method for detecting and tracking a coded signal that is correlated in-phase and quadrature over subintervals of time, wherein an in-phase signal component value of the signal is derived and a quadrature signal component value of the signal is derived for each time subinterval, comprising the steps of:(a) retrieving from a memory stored data (PDI) representing path phase displacement indices; (b) forming in-phase correlation sums (SI) of the in-phase signal component values, wherein each in-phase correlation sum has as its first term the in-phase signal component value from a first time subinterval and successive partial sums are determined by iteratively comparing the retrieved data to a preset condition and applying an appropriate in-phase or quadrature signal component value; (c) forming quadrature correlation sums (SQ) of the quadrature signal component values, wherein each quadrature correlation sum has as its first term the quadrature signal component value from the first time subinterval and successive partial sums are determined by iteratively comparing the retrieved data to the preset condition and applying an appropriate in-phase or quadrature signal component value; and (d) estimating a true path of the signal by determining the correlation sums, in-phase or quadrature, having a maximum absolute value, wherein the estimate of the true path of the signal includes an ending phase.