Partial-correlation-result reconstruction technique for weak global navigation satellite system long pseudo-noise-code acquisition

In global navigation satellite system (GNSS), the signals are very weak. In particular, when the signals are interfered by other signals or shadowed by heavy vegetation, mountains, buildings etc., they will be significantly attenuated and become much weaker. In the situation, for GNSS pseudo-noise (PN)-code acquisition, detection performance is critical. In the study, to improve the detection performance of the previously published double block zero-padding (DBZP) method for weak GNSS long PN-code signals, the authors propose to reconstruct the correlation results of DBZP. Taking the advantage of utilising the correlation results that correspond to part of received signal aligning with local signal and are discarded by DBZP, the technique expands coherent integration time. The effect of the proposed technique on detection and mean acquisition time performance is analysed. It is shown that after reconstructing correlation results the proposed technique expands coherent integration time to twice, improves detection performance about 1.3 dB and consequently further shortens mean acquisition time, whereas it does not increase the implementation complexity of a GNSS receiver. The technique is also applicable to other GNSS long PN-code acquisition methods such as the previously published direct average method and the overlap average method.