A Second Order BPSK-like (SOB) Method for the Acquisition of BOC(1,1)

The envelope of Autocorrelation Function (ACF) of BOC signal has a narrower main lobe that enables higher resolution of acquisition and tracking. However, the existence of multiple secondary peaks and multiple zero crossings can cause signal detection missing and false lock. In order to get rid of this ambiguity, several methods are proposed, such as oversampling, sub-carrier phase cancellation (SCPC), BPSK-like, Autocorrelation SidePeak Correlation Technique (ASPeCT) and Teager-Kaiser (TK) operator. In this paper, these unambiguous methods are briefly summarized and compared, e.g. the BPSK-like method is elaborated. The BOC signal is modeled as the sum of a series BPSK signals with different amplitudes, which is equivalent to multi-carrier modulated signal. An improved BPSK-like method is presented, in which the maximum ratio combination (MRC) is used to receive signal modulated by the first and second carriers. Compared with traditional BPSK-like method, the proposed method can increase the detection probability and reduce the energy loss. FFT based parallel searching strategy is applied in estimating the received signal’s Doppler shift and code delay.