US Patent 7474261 Radiolocalization receiver and signal processor

Pseudo-range processor (20) for a satellite radiolocalization receiver (100) having access to an auxiliary clock (38) used to clock an auxiliary reference timer (40). The auxiliary reference timer (40) is periodically sampled (170) during tracking, in relation to the GPS time kept by the main clock. The processor allows intermittent operations, between periods in a low-power sleep mode during which correlators (25) and main clock (37) are inactive. On wake-up a new sample is taken of the auxiliary reference timer (40), which allows an estimation of the most likely position of the correlation peaks (123a-c). The correlation engine can therefore directly start to search for peaks in appropriate code phase windows, with a high probability of immediate reacquisition.