Multi-pass frequency hop-acquisition correlator

Abstract

A multi-pass frequency hop timing acquisition correlator that produces a more accurate time estimate from the fast acquisition frequency hop signal is disclosed. The time estimate produced by the multi-pass acquisition correlator is more accurate than the ¼ hop estimate produced by single-pass fast acquisition correlators. The multi-pass frequency hop timing acquisition correlator uses a time estimate generated by a previous pass through the multi-pass frequency hop timing acquisition correlator as a starting point for computing a new, more accurate, time estimate. Thus, the second pass through the multi-pass frequency hop timing acquisition correlator produces a time estimate that is relatively more accurate than the time estimate produced by the first pass. The more accurate time estimate produced by the multi-pass acquisition correlator reduces the hardware and time needed by the direct acquisition process to acquire the M-code. In one embodiment, the multiple-pass frequency-hop correlator on the second or third pass provides microsecond-level timing from a GPS M-code fast acquisition frequency hop signal in a jamming environment.