LEO-Assisted Beidou B1C Signal Acquisition Algorithm and On-Orbit Verification

In the occlusion and electromagnetic interference environment, the GNSS navigation signal is seriously attenuated, and traditional GNSS receivers are difficult to capture. For direct capture of weak signals, long-time coherent integration and non-coherent integration can be used to improve the signal-to-noise ratio (SNR) of the signal. However, coherent integration time is limited and bit flipping, and non-coherent integration has a square loss, resulting in a significant increase in the SNR. Taking into account the advantages of LEO satellites with low orbital height and large landing power, this paper proposes a LEO-assisted acquisition algorithm. The code phase and Doppler frequency estimates can be obtained through the assistance of LEO satellites, which can extend the coherent integration time. This method can effectively improve the anti-interference ability of the B1C signal and reduce the average acquisition time. The on-orbit test results show that under the condition of 80 ms coherent integration and 2 times incoherent, B1C anti-interference ability can be improved by 14 dB.