Research of Indoor GPS Signals Acquisition Algorithm

The key of satellite navigation positioning technology is weak signal detection in low-SNR environments. In order to acquire weak GPS signals, this paper analyzes an efficient GPS signal acquisition method, differential correlation, where each current coherently integrated pre-detection sample is multiplied with the complex conjugate of the previous pre-detection sample. The products are then accumulated. By means of mathematical model, the adapted acquisition algorithm based on differential correlation (DF) is derived in detail. By implementing rigorous mathematical analysis, this paper proves that this algorithm outperforms conventional non-coherent integration of coherent integration results (NCH) in the detection of weak GPS signal. The processing loss induced by NCH can be decreased through the use of DF by approximately 3 dB at low carrier-to-noise density ratios. This improvement decreases the acquisition time, representing a substantial improvement in the context of weak GPS signals. Using simulation, we compare the DF acquisition algorithm with the NCH acquisition algorithm. The simulation results indicate that this algorithm is superior to the NCH acquisition algorithm in improving the sensitivity.