# Localization of GNSS Spoofing Interference Source Based on a Moving Array Antenna
## 4 Simulations and Results
### Experiment 1: Spoofing Extraction Effects Based on the Double-Difference Carrier Phase  
Considering that spoofing interference extraction has no restriction on the observation paths, this experiment uses 205 observation points from all five paths to test the effectiveness of the deception interference extraction method proposed in this paper. The location of the spoofing interference source is set to \([500\;500\;100]\), which is the center position of the interference monitoring region. The mean value of the carrier phase measurement error is set to 0, and the standard deviation is set to \(0.005\times 2\pi\) rad. Prior to simulation testing, distinguishing between spoofing interference signals and genuine satellite signals is unattainable. The spoofing interference extraction methodology in this paper necessitates the concurrent utilization of eight signal tracking channels to monitor both the authentic satellite signal and the spoofed interference signal, thus enabling carrier phase measurements on all eight satellite signals. We numbered the 8 tracking channels as 1-8, with channels 1 and 2 receiving the Sta1 signal, channels 3 and 4 receiving the Sta2 signal, channels 5 and 6 receiving the Sta3 signal, and channels 7 and 8 receiving the Sta4 signal. The carrier phase measurements between antenna elements 1 and 0 are utilized for the carrier phase single-difference calculation in the experiment. Subsequently, the single-difference measurement values of signal channels 1 and 2 are subtracted from those of signal channels 3-8, respectively, to compute the double-differenced carrier phase. The comparison between the double-differenced carrier phase observation values and the set threshold is depicted in Figure 9. Figure 9 presents the double-differenced carrier phase results for channels 3-8 and channel 1, while Figure 9 displays the results for channels 3-8 and channel 2. The horizontal axis in Figure 9 represents the sequential numbering of the observed points, while the vertical axis corresponds to the double-difference carrier phase measurements at these points, denoted in units of \(2\pi\) rad. We set the double-difference carrier phase threshold \(Th\) for spoofing interference extraction as \(0.04\times 2\pi\) rad. Although there is a situation in Figure 9 where sporadic double-difference measurement results are below the threshold, it lacks continuity. In Section 3.1, the method stipulates that there must be five consecutive observation points with double-difference carrier phase measurements smaller than the set threshold in order to determine that the two satellite signals are from the same spoofing interference source, thus avoiding such false alarms. The double-difference measurement values of 4-2, 6-2, and 7-2 in Figure 9 fall below the threshold, indicating that the satellite signals tracked by channels 2, 4, 6, and 7 originate from the same deceptive interference signal. The effectiveness of the spoofing interference extraction method in this paper is tested using 205 observations from the five paths. Every five observation points is a test, making a total of 41 tests. The results are statistically analyzed, and the probability of successful extraction of spoofing interference signals is 100%, and the missing alarm rate is 0%. The experimental results demonstrate that the extraction of spoofing interference based on the method double-differenced carrier phase can effectively separate the spoofing signals from the authentic signals. It is worth mentioning here that multi-path can affect the effectiveness of the method in this paper and generate false positives in real-world applications, and we would like to reduce the effect of multi-path on the effectiveness of the method by improving the application details in this paper. Multi-path may affect the effectiveness of the proposed method in a certain multi-path region for a short period of time, but as the monitoring platform moves over a large area, it can avoid or reduce the effect of multi-path on the effectiveness of the proposed method.