Patent ID: 7852905

Claim:
A method for measuring time related to satellite data messages for use with a satellite positioning system (SPS), the method comprising: receiving in a mobile SPS receiver at least a portion of a satellite data message; determining a first record of the at least a portion of the satellite data message by despreading a PN code from the satellite data message, wherein the satellite data message comprises a plurality of signal samples, each signal sample having an in-phase portion and a quadrature-phase portion, and wherein the PN code comprises a plurality of chips, the despreading step comprising: selecting one of the in-phase portion and the quadrature-phase portion of a first signal sample of the plurality of signal samples; multiplying the selected portion of the first signal sample with one of the plurality of PN code chips to obtain a first product, wherein the selected portion is either an odd portion or an even portion of the selected portion of the first signal sample as selected by an odd-even switch; multiplying the selected portion of a second signal sample of the plurality of signal samples with the first PN code chip to obtain a second product, wherein the second signal sample succeeds the first signal sample, wherein the selected portion is either an odd portion or an even portion of the selected portion of the second signal sample as selected by the odd-even switch; and grouping the first product with the second product to obtain a first sum; and transmitting from the mobile SPS receiver the first record to a remote basestation for the purpose of determining a time indicating when the first record was received at the mobile SPS receiver.