Joint Vector Tracking Loop in a GNSS Receiver

The GNSS signal received by a GNSS receiver consists of many signals transmitted from all visible satellites at single or multiple carrier frequencies. These signals, which are from different satellites at the same frequency, can interfere with each other; while the codes and carriers of all satellite signals are related. In order to mitigate the interference between GNSS signals and to take full advantage of correlation between codes and carriers, we model the received complex baseband signal instead of outputs of correlators as a linear model and propose a joint vector tracking loop based on the linear model to track codes and carriers jointly regardless of whether the RF module and the digital processing module are driven by the same clock or not. The proposed joint vector tracking loop can mitigate the interference between GNSS signals, and it also can improve the tracking sensitivity and the tracking accuracy. Although we only take GPS L1 C/A code signal as an example herein to simplify analysis, the proposed linear model and joint vector tracking loop can be easily expanded to the case of multi-frequency and multi-constellation.