Oscillator frequency correction in GPS signal acquisition

A method for correcting oscillator frequency error in GPS signal acquisition, comprising the steps of:

• receiving at least one broadcasted GPS signal;
• constructing a code phase estimate from a signal envelope accumulation;
• estimating a plurality of Doppler offsets and centering the plurality of Doppler estimates using the code phase estimate;
• correlating the signal to produce correlation magnitudes that follow a sin(x)/x curve of a Doppler modulation for each of the plurality of Doppler estimates;
• calculating a magnitude separation between the maximum and minimum correlations corresponding to the peak and null states of the curve;
• and
• searching the separations to finding the Doppler estimate producing the largest magnitude separation, the found Doppler estimate defining a frequency error estimate for the at least one broadcasted GPS signal.

A method for correcting oscillator frequency error in GPS signal acquisition, comprising the steps of:

• receiving at least one broadcasted GPS signal;
• constructing a code phase estimate from a signal envelope accumulation;
• estimating a plurality of Doppler offsets and centering the plurality of Doppler estimates using the code phase estimate;
• correlating the signal to produce correlation magnitudes of a Doppler error modulation for each of the plurality of Doppler estimates;
• curve fitting the Doppler error modulation to a sin(Tƒ/2)/(Tƒ/2) curve, where T is the coherent integration interval, and ƒ is the frequency error, using at least two correlation magnitudes;
• and
• using the shift in Doppler value of the curve fit to estimate a Doppler error defining a frequency error for the at least one broadcasted GPS signal.