# Spoofing Traction Strategy Based on the Generation of Traction Code
## 4 Discussion
### Discussion on Experimental Results  
This section discusses the experimental results obtained in Sections 3.2 and 3.3.  
First, the results of these strategies are discussed to clarify the feasibility of the proposed strategy.  
All \(\tau_{\text{sl}}\) values in Figures 13(a), 14(a) and 14(a) finally approach 0, indicating successful code loop traction of the three strategies. According to Figure 14(a), the output of filter fd\({}_{1}\) is finally equal to the spoofing Doppler f\({}_{\text{drag}}\), and the carrier loop traction of Strategy 2 is successful.  
However, as shown in Figures 13(a) and 14(a), each received observation has a different degree of distortion under the two conventional strategies. By comparing Figures 13(a), 13(b) and 13(c), it can be observed that the experimental results are consistent with the simulation results, which confirms the correctness of the simulations.  
From Figure 14, it can be seen that the received observations of the proposed strategy are stable without distortion, and the code phase of the tracking loop follows the preset code phase of spoofing, which verifies the feasibility of the proposed strategy under noise.  
The second part presents the analysis of the proposed strategy under different spoofing scenarios.  
In Tables 4-8, it can be observed that the observations' RMSE percentage change in the proposed strategy is significantly better than those of Strategies 1 and 2, and the observations' RMSE percentage change in Strategy 2 is the worst. Based on these data, we can infer that in all designed spoofing scenarios, the implementation of the proposed strategy has no significant effect on the statistical value of the signal.  
As shown in Figure 20 and Table 8, the obtained results of the narrow correlator are similar to those of the wide correlator. The proposed strategy can also address narrow pulse-aperture correlators.  
Because the 30 dBHz C/N\({}_{0}\) is already a very weak GNSS signal, there will be some difficulties in estimating the genuine signal in the first step. In Table 4, significant changes in the observations are easily lost in the noise;therefore, the meaning of the obtained results is relatively limited. As shown in Figure 19a, the received results are very poor, which also means that there will be some difficulties in the acquisition and extraction of navigation messages. However, as can be seen from Figure 19b, the phase is successfully pulled, so the proposed spoofing traction strategy also exhibits good performance under the condition of a poor C/N\({}_{0}\).  
In conventional Strategy 1, the statistics of code Doppler and carrier Doppler are small because this strategy directly superimposes spoofing signals of the same format, and the effect of correlation peak superposition is equivalent to power enhancement, thus reducing the output of the phase discriminator to a certain extent.  
In special scenarios, such as a battlefield, the GNSS of the defense side may be enhanced to improve the service accuracy and reduce the possibility of spoofing. Figure 17 and Table 7 demonstrate that the proposed strategy performs well in the case of a power-enhanced signal.  
The third part presents the performance analysis of the proposed strategy in the context of the SQM technique.  
From Figures 21-24, it can be observed that the Ratio Test metric values of the genuine signal are in the range \(\pm\)0.15, while the metric values of Strategies 1 and 2 are far beyond this range. As expected, the metric values of the proposed strategy are within a safe range. The threshold value can be easily derived according to the theory presented in [13], given a determinate false detection probability. A threshold is built around the shape of the metric function, and can be used to detect the presence of distortions in real time. These results demonstrate that this strategy can bypass the SQM detection.