Abstract: A method for selecting a local C/A code for GPS signal processing includes performing an autocorrelation of a received GPS C/A code with a plurality of versions of a local coarse acquisition (C/A) code. In such an autocorrelation, each local C/A code version is autocorrelated with the received GPS C/A code over a plurality of autocorrelation periods, and an autocorrelation result is generated for each autocorrelation period. A maximum autocorrelation result and a minimum autocorrelation result are determined from among the autocorrelation results of each C/A code version. Next, one of the local C/A code versions is selected based upon that version's maximum autocorrelation result and the minimum autocorrelation result.

Abstract: A method for acquiring a GPS signal includes receiving a GPS signal portion over a coarse acquisition (C/A) frame period. The received GPS signal portion is stored and correlated to each of a plurality of versions of a reference coarse acquisition code to obtain a respective plurality of autocorrelation values. A peak value is selected among the autocorrelation values, the peak value corresponding to a version of the reference coarse acquisition code which is most aligned with the received GPS signal.

Abstract: A method for acquiring a GPS signal includes receiving a GPS signal portion over a coarse acquisition (C/A) frame period. The received GPS signal portion is stored and correlated to each of a plurality of versions of a reference coarse acquisition code to obtain a respective plurality of autocorrelation values. A peak value is selected among the autocorrelation values, the peak value corresponding to a version of the reference coarse acquisition code which is most aligned with the received GPS signal.

Abstract: A variable rate correlation circuit for conserving power includes a variable clock source, a local PN source, and a correlator. The local PN source further includes a local generator and a resampler. The variable clock source provides a normal clock rate and a lower clock rate. The local generator supplies the local PN sequence at the normal clock rate. The resampler receives the local PN sequence sampled at the normal clock rate and outputs the local PN sequence sampled at the lower clock rate. The correlator receives the lower sampled local PN sequence, the received PN sequence, and the lower clock rate signal, correlating the received and local PN sequences at the lower clock rate to produce a. correlated result.

Abstract: The present invention provides a CDMA receiver which uses less expensive, more manufacturable digital filters in combination with noise cancellation circuitry to attenuate highly correlated signals. In addition, the CDMA receiver employs digital IF sampling in the baseband conversion process to remove superimposed DC voltages from the baseband data, obviating the need for DC offset voltage generators.

Abstract: The present invention provides for an improved transceiver architecture using fewer frequency synthesizers. The number of frequency synthesizers is reduced by utilizing an existing frequency source having a frequency slightly offset from the ideal sampling frequency. In one embodiment, an improved transceiver capable of communicating CDMA encoded signals is presented. The transceiver includes a first frequency synthesizer producing a first mixing tone, a second frequency synthesizer producing a second mixing tone, a first sampling source producing a first sampling signal, and a receiving channel. The receiving channel includes a first mixer, a second mixer, and an analog to digital converter (ADC). The first mixer receives the incoming CDMA signal and the first mixing tone, producing a first IF signal. The second mixer receives the first IF signal and the second mixing tone, producing a second IF signal in response.