Multipath processing for GPS receivers
AssigneeSiRF Technology, Inc.
InventorsSanjai Kohli, Charles R. Cahn
Life of this patent
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Abstract
A GPS receiver system determines the presence of trackable signals at code delays less than the prompt delay being tracked for a particular signal and changes the prompt delay to correspond to the smallest code delay having a trackable signal. Trackable signals at large code delays are multipath signals and may be separately tracked to aid in dead reckoning. The trackable signals at code delays not adjacent to the current tracked prompt delay may be tracked in the same channel as the prompt delay so that all satellite channels are continuously evaluated for multipath signals being tracked or a non-satellite specific channel may be used to sequentially step through the satellite signals to evaluate multipath on a satellite by satellite basis.
Claims12
A method of operating a spread spectrum receiver comprising:
- tracking a first signal as a direct signal;
- tracking a second signal as a multipath signal;
- monitoring the delay between the direct signal and the multipath signal;
- when the delay is within 1.5 chips, modeling the correlation products for the multipath signal;
- and
- compensating for the modeled correlation product.
A spread spectrum receiver comprising:
- means for tracking a first signal as a direct signal;
- means for tracking a second signal as a multipath signal;
- means for monitoring the delay between the direct signal and the multipath signal;
- means for modeling the correlation products for the multipath signal when the delay is within 1.5 chips;
- and
- means for compensating for the modeled correlation product.
Dependencies are inferred from the claim text.