Double block zero padding differential coherent weak signal acquisition algorithm under ionospheric interference

Abstract

The Global Positioning System (GPS) is widely used, which can provide users with all-weather and real-time navigation and positioning services. In a complex space environment, the propagation of GPS signals is easily disturbed by ionospheric scintillation, which results in signal strength decline. Aiming at the weak signal acquisition problem of GPS receiver, this paper proposes a weak GPS signal acquisition algorithm based on Double Block Zero Padding (DBZP) and improved differential coherent integration. After the signal is processed by DBZP, it is further processed by differential coherent integration, which effectively reduces the related power loss caused by Doppler frequency shift. In addition, the signal strength is enhanced by correlation accumulation technology, and the error caused by bit inversion of satellite signal is eliminated by bit inversion estimation technology. The simulation results show that the algorithm can successfully capture weak GPS signals, and the capture peak is more obvious, which improves the robustness of the algorithm. When the GPS signal suffers from severe ionospheric scintillation interference, the acquisition probability of Signal to Interference Ratio (SIR) still reaches 50% at -35dB. When the SIR is increased to -33dB, the probability will be further increased to 92%.