An unambiguous acquisition algorithm for BOC modulated signals Based on weighting adjustment

Abstract

The Binary Offset Carrier (BOC) modulated signals has been extensive used Global Satellite Navigation System (GNSS), due to the effect of multiple side peaks of the BOC modulated signals in the traditional acquisition algorithm, the result is blurred. This paper proposes a acquisition algorithm for BOC modulated signals by assigning weights to crosscorrelation function (AWCCF), it can eliminate side peaks to achieve the purpose of capturing without ambiguity. It respectively intercepts the start and end of the local sub-carrier square wave which is corresponded to the modulation order every chip which is corresponded to the PRN code, and sets the remaining positions to zero to obtain two new sub-carriers. The new sub-carriers modulated PRN code cross-correlate with the base-band received signals and the results are two sequence values, combine these two sequence values and normalize them, we get the wights. The AWCCF values are obtained by the weights multiplying with the correlation function values which are generated by using traditional acquisition algorithms. The AWCCF can be applied to a variety of BOC modulated signals whose modulation order is an integer and effectively eliminate side peaks. Finally, the simulation results show that the AWCCF has better performance than some other algorithms and can work in low signal to noise rate (SNR) conditions.