Abstract:

A noncoherent unambiguous tracking method based on the S curve shaping technique is proposed to solve the ambiguous tracking problem of Alternative Binary Offset Carrier (AltBOC) modulated signal used in global navigation satellite systems. In the proposed method, the cross correlation functions between two linear combined codes and the received signal are used to generate the noncoherent S curve. The principle for setting asymmetrical unambiguous objective curve with outstanding multipath mitigation performance is discussed. An S curve shaping technique based on the least square solution of linear equations is proposed. The resulting weights for tracking the pilot signal of AltBOC(15,10) and an tracking loop structure easy to implement are given. Simulation results reveal that the proposed method can make the S curve close to the objective curve in the sense of the least square criterion. The proposed tracking loop has better performance in tracking accuracy and multipath mitigation than traditional AltBOC unambiguous tracking loops.

Key words: Global navigation satellite systems(GNSS), Alternative binary offset carrier (AltBOC), Unambiguous tracking, S curve shaping method