GNSS/Pseudolite Signal Re-Acquisition with the aid of INS in Short Signal Blockage Scenarios

Based on the concept of ultra-tight integration of GSSS, Pseudolite (PL) and Inertial Navigation Systems (INS), this paper proposes a method to execute quick GNSS/PL signal re-acquisition in short signal blockage scenarios. The key aspect of this method is that the INS measurements are used not only to aid the tracking loops, but also to aid re-acquisition when a signal blockage happens. The re-acquisition unit has advantages over the traditional acquisition methods in that it adopts short time (1ms) data only, is inherently immune to the problem of navigation data transition. Simulation experiments were conducted to compare the performances of the reacquisition algorithm in different C/N0 conditions with different INS Doppler aiding offsets. The results show that, under such conditions that the C/N0 is above 36dBHz and INS Doppler estimation offset is below 50Hz, the signal can be re-acquired within the range of ±30Hz of frequency bias, which can be tracked by the following tracking unit.