Patent ID: 7453961
Filing Date: 2008-11-18
Classification: G01C,G01S,H04B

Abstract:
1. An apparatus for determining the timing of a received signal, the received signal including one or more time-delayed versions of a reference signal traveling over respective different signal paths, the apparatus comprising: a correlator configured to iteratively correlate the received signal with the reference signal to produce a correlated signal; a chip-level energy extractor configured to emphasize the correlated signal in peak chips containing signal peaks by reducing the amplitude of the correlated signal in other chips, wherein the signal peaks correspond to potential signal paths of the received signal; a sample-level energy extractor configured to emphasize the correlated signal in peak samples in the peak chips by reducing the amplitude of other samples in the peak chips; and a processor configured to iteratively modify the received signal supplied to the correlator until the processor determines that the correlated signal includes a signal peak corresponding to a direct path of the received signal, the direct path providing the timing of the received signal, wherein in each iteration, the processor regenerates the reference signal corresponding to at least a greatest signal peak in the correlated signal and modifies the received signal supplied to the correlator to remove contributions from the regenerated reference signals, such that the correlated signal in successive iterations excludes contributions from signals determined in previous iterations not to correspond to the direct path.