A receiver terminal receives a frequency from an external reference
oscillator portion, which is more accurate than that of a frequency
generated within the receiver in a local oscillator portion. The
frequency from the local oscillator portion is measured using the
external frequency as the reference, which determines the error in the
local oscillator frequency relative to the external reference and permits
the local oscillator frequency to be corrected to within the error of the
external oscillator frequency. A plurality of candidate values for the
remaining local frequency error are selected within a predetermined
frequency range to include any remaining error of the local oscillator
frequency. The received signal from a satellite is correlated with a
matching pseudorandom code to detect the signal and measure the signal
delay and Doppler shift of the signal relative to the corrected local
oscillator frequency. The delay value is used to obtain a pseudorange
measurement and the measured Doppler shift permits further correction to
the local oscillator frequency, thus reducing the frequency search range
for the remaining satellites.