Abstract:

Aiming at the tracking ambiguity problem caused by the multi-peak characteristic of the Binary Offset Carrier and its derivative signals autocorrelation function,this paper proposes an unambiguous tracking algorithm based on the characteristics of the signal correlation function.First,the general expression for the cross-correlation function for the BOC reference and derivative modulation signal is obtained by the shape code vector constructed in this paper.The pseudo code of the received signal is used as a local reference signal,and a special local code waveform is designed to perform correlation operations with the corresponding received signal to obtain a signal correlation sub-function.Then,the sub-functions are recombined using the reconstruction rules proposed in this paper,and the edge peaks are completely eliminated and a new correlation function with a single peak is retained.The code tracking loop structure of the improved tracking algorithm,compared with the traditional code tracking loop structure,reduces the filter circuit,the structure is simplified,and the hardware implementation complexity is also reduced.Simulation results show that the secondary peak of the correlation function is eliminated while retaining the sharpness of the main peak.By comparing with the traditional tracking algorithm,it can be seen that the code tracking accuracy of this algorithm is higher under the premise of the same carrier-to-noise ratio.The phase discrimination function does not have any false lock points except the zero crossing point,and will not cause a false lock problem.Compared with the traditional tracking ambiguity elimination algorithm,this method can effectively apply BOCs(m,n) and CBOC(6,1,1/11) signals without ambiguity tracking.

Key words: binary offset carrier, unambiguous tracking, shape code vector, sub-function combination