Sirf Technology, Inc.

Motorola Corporation

Xiang Yuan

Gang Xie

Ravikiran Nory

Thomas Michael King

George Jeffrey Geier

James Stephen

Qutub Salman Syed

Rahul Vohra

A system and method for providing code tracking in a CDMA based communications receiver. In example systems and methods, a CDMA receiver, such as a GPS receiver, receives a signal and demodulates the signal to yield a digital IF signal. The digital IF signal is down-converted to a received code signal. Early, prompt and late correlation results are determined by correlating the received code signal with early, prompt and late duplicates of the received code signal. The early, prompt and late correlation results are used to calculate a code phase error using a noise-floor independent function of all three correlation results.

Noise floor independent delay-locked loop discriminator

An improved time-to-first-fix (TTFF) for GPS systems is provided through a comparison of the time-of-week (TOW) to the sub-frame identification (ID). In one embodiment, this comparison comprises dividing the TOW to form a ratio and performing a modulus operation on the ratio to form a remainder, which is then incremented. If the incremented remainder equals the sub-frame ID, the TOW is assumed to be valid, thereby providing a time of transmission. The time of transmission may then be used to calculate pseudoranges and determine a receiver's location.

Time-to-first-fix for position determination

An embodiment and method of the present invention includes a frequency lock loop (FLL) having an improved frequency error estimation and a low bit error rate (BER) in data demodulation by calculating and using an improved averaged phase rotation using 'valid' phase rotation samples.

Method and apparatus for frequency discriminator and data demodulation in frequency lock loop of digital code division multiple access (CDMA) receivers

In a Global Positioning System (GPS) receiver, rather than storing both GPS satellite ephemeredes and almanacs to the GPS receiver's on-chip non-volatile memory, storing into the non-volatile memory only the more recent ephemeris or almanac data for each satellite. When an ephemeris expires, the parameters in the ephemeris are converted into corresponding parameters of an almanac. The ephemeris or almanac is used to determine whether a given satellite is visible to the GPS receiver. A method of the present invention allows efficient use of the memory space in the non-volatile memory. A study by the inventors shows that differences in positions and velocities of satellites estimated using aged ephemeris and almanac data associated with the same week number are insignificant.

Method for a space-efficient GPS receiver

A method in a satellite positioning system (SPS) receiverincluding acquiring a plurality of at least two SPS signals, estimating frequency error for each of the plurality of SPS signals, and compensating for the frequency error of each of the plurality of SPS signal based on the estimated frequency errors for all of the plurality of SPS signals.

Growing community of inventors

Chandler, AZ, United States of America

Xiang Yuan