On the Scalar-Vector Fusion Loop for GNSS Signal Tracking

Yiming Deng, Jun Luo, Xiaoguang Zhou, Qi Zhou, Wei Li

Abstract: The vector tracking loop has a dominant feature of utilizing the interaction among all tracking channels to maintain signal tracking in harsh environment. However, one of the most frequently stated issues of vector tracking is that vector loop seems to cause equally bad problem as strong channels will be contaminated by weak channels in turn during navigation filtering stage, thus leading to deteriorative tracking performance. It has been noted that traditional scalar tracking loop based on PLL and DLL usually tends to be relatively more concise and accurate than vector loop when satellite signal is in good condition with no interference or blockage. Previous research concerning cascade vector tracking has shed light on the way to design scalar-vector fusion loop. Therefore, this paper proposes a fusion loop using tracking-tracking (T-T) Kalman filter to combine NCO updating parameters from both scalar and vector loops. In this way, the precision from scalar tracking and the channel coupling from vector tracking are well unified