System and method to estimate the location of a receiver

Abstract

System and method to determine the location of a receiver are provided. The received signal is decomposed into signal chunks that are then correlated with the reference signals of the transmitting sources. In some embodiments, the signal chunks may be shorter than the period of the reference signals. For each signal source, a grid of correlation values is constructed containing one column of correlation values for each signal chunk. Each column contains correlation values for several code-phases. Probes are executed in the grid to acquire the location-determining signals. In some embodiments, a probe includes calculating the fourier transform of a row in the grid, yielding correlation values associated with a refined set of frequency values. Potential acquisitions are verified by processing increasing portions of the received signal. Confirmed acquisition may be used to aid further acquisitions. Some embodiments eventually compress the received signal down to a one period duration by means of an ultra-stacking method. Additional verification, comprising multi-peak test and multi-path tests, may be performed on the correlation magnitude curve obtained from the ultra-stacked signal. Finally, refined code-phase values are extracted from these correlation magnitude curves.