Patent ID: 7920620

Claim:
A method for reducing a number of calculations required to correlate an incoming spread spectrum signal received by a GPS receiver and encoded with a pseudorandom code, comprising: determining, for the spread spectrum signal, partial accumulations that are repeated in a correlation process of the spread spectrum signal using a data slice of the spread spectrum signal made up of in phase (I) signal data and quadrature phase (Q) signal data correlated with pseudorandom codes, wherein the data slice of the spread spectrum signal includes a plurality of data bytes and a plurality of pseudorandom code bytes; removing at least a portion of the partial accumulations that are repeated in the correlation process of the I signal and the Q signal data with the pseudorandom codes and results in remaining partial accumulations in the correlation process; storing the remaining partial accumulations in at least one table that is accessible by the GPS receiver; and using, by the GPS receiver, the data slice to look up a corresponding accumulation value in the at least one table during the correlation process to determine when a locally generated pseudorandom code and the incoming pseudorandom code received at the GPS receiver are correlated, wherein the at least one table is constructed for one of the terms of the spread spectrum signal.