Patent ID: 8593342

Claim:
A method of reducing a satellite frequency search range in a satellite code division multiple access (CDMA) signal receiver, comprising: identifying a frequency uncertainty for non-geostationary satellite signals, the frequency uncertainty including a receiver crystal oscillator frequency bias; searching for a signal from a geostationary satellite; acquiring said geostationary satellite signal; estimating the receiver crystal oscillator frequency bias using the acquired geostationary satellite signal, wherein estimating the receiver crystal oscillator frequency bias includes estimating Doppler frequency uncertainty due to movement of the CDMA signal receiver relative to the geostationary satellite; reducing the frequency uncertainty using the estimated receiver crystal oscillator frequency bias; and calculating a frequency search range for subsequent non-geostationary satellite signals to be acquired based on the reduced frequency uncertainty, wherein calculating the frequency search range includes adding together only (1) a Doppler frequency uncertainty caused by movement of said CDMA signal receiver relative to the Earth's surface and (2) a Doppler frequency uncertainty caused by movement of the orbit of the non-geostationary satellite relative to the Earth's surface.