Rapid acquisition methods and apparatus for gps signals background

The transmitted signal containing the characteristic sequence repeated periodically is used, and the method and equipment for deciding the position of a receiver are indicated. This equipment and method are a communications system, and effective in a system like A*GPS especially used by GSM and a UMTS cellular phone system desynchronized. The received signal is memorized by a receiver only repeatedly [of the sequence repeated periodically / at least 2]. FFT computation is performed, and pruning of the consequential data frequency sample is answered and carried out to the remains frequency by which the hypothesis was carried out. This decreases the subsequent number of calculations and processing time which are needed. Correlation series is determined from the sample by which pruning was carried out and reference frequency sample corresponding to the transmitter by which the hypothesis was carried out. If coincidence is discovered, code phase offset is determined, and if not discovered, a process will be repeated on another remains frequency by which the hypothesis was carried out. Before this inspection, the correlation series of a large number obtained by being similar is also un-coherent, and can be put together. [Selection figure] Fig. 3