A Global Navigation Satellite System (GNSS) receiver and associated method
capable of acquiring weak GNSS signals from a plurality of GNSS
satellites produces a GNSS signal's code time, carrier frequency, and
data bit transition parameters for subsequent signal tracking and
position fixing. The GNSS receiver includes a baseband signal processor
with special functionalities for acquiring weak signals. In a preferred
embodiment, the time and frequency uncertainty space is reduced using
available information and then special techniques are used to rapidly
search the remaining uncertainty space. Successive reversal of
short-length correlations within a data bit interval (a block) enables
data bit transition detection and data bit sign correction prior to
coherent integration. Fast Fourier Transform (FFT) is applied as a bank
of bandpass filters to coherently accumulate blocks of short-length
correlations over extended coherent integration intervals to boost the
signal power while averaging noise out despite unknown data bit
transitions.