When reception of satellite signals is lost, for example, one minute, satellite signals are searched firstly in accordance with a narrow-band search mode by varying a search frequency within a range of Doppler frequency shift estimated by a moving speed of a GPS receiver, for example, .+-.600 Hz for...http://www.google.co.uk/patents/US5036329?utm_source=gb-gplus-sharePatent US5036329 - GPS satellite signal tracking method for GPS receivers
