## 4 Experiments and Discussion
### Performance Analysis of the Resampling Strategy
From the bold rows listed in Table 2, the correlation magnitude of Satellite PRN12 was a little smaller than that of Satellite PRN6 when acquired with the resampling strategy. Nevertheless, the correlation ratio of Satellite PRN12 was still the biggest among all acquired satellites. The acquisition results of the resampling strategy kept consistent with that of the conventional acquisition algorithm in Table 2. It proves that setting the correlation ratio as acquisition threshold can enhance the acquisition performance, especially for cases: (1) correlation magnitudes are too small in the search space due to noise in the received broadband signal; (2) there exists more than one value which is higher than the conventional correlation threshold (always a constant of correlation magnitude). Satellites acquired by the resampling strategy and the conventional acquisition algorithm were completely the same, as illustrated in Figure 8. This has proved the effectiveness of the proposed resampling strategy for signal acquisition. Furthermore, for acquired (cyan and bright green bars) and not acquired (dark blue and blackish green bars) satellites, the correlation magnitude of the resampling strategy (the left \(Y\) axis) was about 10% that of the conventional one (the right \(Y\) axis), corresponding to results in Table 2. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Acquired**} & \multicolumn{5}{c}{**Acquisition without the Resampling Strategy**} & \multicolumn{5}{c}{**Acquisition with the Resampling Strategy**} \\ \multicolumn{2}{c}{**Satellites**} & \multicolumn{5}{c}{**Acquisition with the Resampling Strategy**} \\ \hline
**PRN** & **CNo** & **Frequency** & **Doppler** & **Code Phase** & **Magnitude** & **Ratio** & **Frequency** & **Doppler** & **Code Phase** & **Magnitude** & **Ratio** \\  & **(dB-Hz)** & **(MHz)** & **(Hz)** & **(samples)** & **/** & **/** & **(MHz)** & **(Hz)** & **(samples)** & **/** & **/** \\ \hline
5 & 38.0 & 7.39649 & \(-\)3507 & 701962 & **21976** & 3.9492 & 7.39649 & \(-\)3508 & 731963 & **2210** & 3.9103 \\
6 & 42.8 & 7.40103 & 1032 & 356345 & **40958** & **6.8311** & 7.40103 & 1033 & 356347 & **4033** & **6.2993** \\
12 & 43.1 & 7.39853 & \(-\)1470 & 193389 & **40928** & **7.0512** & 7.39853 & \(-\)1465 & 193940 & **3983** & **7.2284** \\
17 & 33.7 & 7.40119 & 1187 & 879016 & **14909** & 2.6156 & 7.40119 & 1186 & 879013 & **1546** & 2.6621 \\
24 & 33.2 & 7.40152 & 1522 & 829115 & **14041** & 2.6483 & 7.40152 & 1522 & 829119 & **1342** & 2.2496 \\
25 & 35.9 & 7.39697 & \(-\)3027 & 621138 & **18820** & 3.4106 & 7.39697 & \(-\)3030 & 621140 & **1843** & 3.2997 \\
29 & 27.6 & 7.39708 & \(-\)2920 & 933174 & **12710** & 2.1654 & 7.39708 & \(-\)2922 & 933179 & **1196** & 2.1817 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Acquisition results of the received signal in Dataset 1 without/with the resampling strategy. Figure 8: Acquisition results for GPS L2C satellites without/with the resampling strategy. Doppler frequency shift, code phase offset, and correlation ratio of acquired satellites in Table 2 can be demonstrated clearly in the search space of frequency and code phase, for instance, the acquisition result of Satellite PRN12 shown in Figure 9. The correlation peak occurred at the point of frequency \(\hat{f}=7.39853\) MHz and code phase \(\hat{\theta}=193394\) (samples). The highest peak was much bigger (R\({}_{c}>7\)) than other correlation magnitudes in the search space. Therefore, Satellite PRN 12 was acquired successfully, the carrier frequency is 7.39853 MHz and code phase is 0.365\(\pi\) (1866 chips). The acquisition results were adopted as estimated parameters for the subsequent signal tracking. Aimed at investigating the sensitivity of the resampling strategy under weak signal conditions, extensive Monte Carlo simulations were performed by employing a high-confidence software IF signal simulator [38].