Patent ID: 6384774
Filing Date: 2002-05-07
Classification: G01S,H03J

Abstract:
A GPS receiver for receiving GPS signals transmitted from a GPS satellite comprising:clock generator means for generating a reference clock signal; radio frequency means operable in synchronism with the clock signal for receiving a GPS signal of a radio frequency transmitted from the GPS satellite and generating a GPS signal of an intermediate frequency; and data extraction means for scanning signal-to-noise ratios of the generated GPS signal over a search frequency band and detecting a frequency at which a signal-to-noise ratio of the generated GPS signal is higher than a threshold ratio in the searched frequency band to extract GPS data from the generated GPS signal, wherein the data extraction means sets the search frequency band to a first frequency band in a normal mode and to a second frequency band in a band correction mode, the first frequency band having a first center frequency determined based on an estimated Doppler shift of the GPS satellite and a band width determined based on a generally maximum temperature-dependent change in a frequency of the reference clock signal, and the second frequency band having a band width determined based on a generally maximum aging-dependent change in the frequency of the reference clock signal.