GPS receiver having improved signal acquisition at a low signal to noise ratio

摘要

A GPS receiver having a fast acquisition of a GPS signal having a low signal-to-noise ratio. The GPS receiver uses an adjustable local frequency for iteratively downconvertig raw GPS signal samples to baseband GPS signal code data, combining a plurality of code epochs of the GPS signal code data in chunks and superchunks for providing representative code epochs, and correlates the representative code epochs to a replica code epoch for providing correlation times. Two or more correlation times are used to determine a correlation time difference. The correlation time difference is indicative of a residual frequency error. The error is used for correcting the local frequency. GPS pseudoranges are computed from the correlation times when the residual frequency error from the corrected local frequency is below a threshold.