Design and Implementation of a Real Time BDS Scalar-Vector Tracking Receiver

The advantage of GNSS vector tracking (VT) has been thoroughly analyzed. Different from scalar tracking in which each channel works independently, vector tracking combines all channels through a Kalman filter and drives all numerically controlled oscillators (NCO) simultaneously. This feature enables vector tracking based receiver to be more robust against signal interference and blockage. Most current studies have already tested the performance of vector tracking on post processing software receivers. For the purpose of improving the applicability of vector tracking in real-world situation, this paper presents a scheme of vector delay lock loop (VDLL) based real time scalar-vector tracking receiver. The proposed receiver has the ability to switch into vector tracking from scalar tracking swiftly as soon as the signal loss is detected. An extended Kalman filter (EKF) is used to calculate navigation solution. In this paper the theory of vector tracking is first reviewed briefly. Then the system architecture of developed receiver is described in detail. Finally, in the experiment section an analog front end was used to collect live BDS signal, and static position experiment was conducted to verify the superiority of scalar-vector tracking to conventional scalar tracking in the scenario with signal blockage. Results show that the developed real time scalar-vector tracking receiver is able to obtain correct navigation solution constantly during signal loss while scalar receiver cannot. In conclusion, the superiority of vector tracking loop to conventional scalar tracking loop in the environment with signal blockage is verified.