## 4 Experimental Verification
### Experiment on High Power Control Algorithm of Spoofing Signal  
In experiment 1, high power control algorithm was used for spoofing signal. The design experimental procedure is as follows: 1 First, PolaRx5 receiver is cold-started to ensure that the receiver is in the state of signal loss-locking after the receiver is suppressed for a long duration by the signal; 2 after cold start, signal simulator is used to generate 6 channels of L1 authentic signals and 6 channels of same SVID spoofing signals, each branch spoofing signal has an initial code phase offset of 500 m and an initial carrier phase offset of 500 m with respect to the authentic signal, the spoofing signal is consistent with code rate and carrier phase rate of the authentic signal, compared with authentic signal, the power advantage of spoofing signal is 8 dB, all signals are simultaneously injected into receiver from the connected feeder to simulate the spoofing of the receiver in the signal acquisition phase. The process lasts for 3 min; 3 after 3 min, the other parameters of each spoofing signal are kept unchanged, only the code rate is adjusted to 1 m/s and the carrier phase rate is adjusted to 1 m/s, which increases code phase and carrier phase by a fixed slope. The duration of this process is 3 min. After 246 s, the experimental key instruction design is depicted in Figure 6.  
In Figure 6, \"OFFSET\" indicates the code phase offset, carrier phase offset, relative power gain relative to authentic signal, command start time, and duration time; \"RAMP\" indicates the initial code phase offset, initial carrier phase offset, initial relative power gain,  
Figure 5: Experimental platform setup. Figure 6: Experimental instruction design in experiment 1.  
code rate and carrier phase rate, power increase/decrease rate, relative to authentic signal, and command start time and duration time. The following analyzes the changes of Doppler frequency, carrier-to-noise ratio, and Earth-Centered, Earth-Fixed (ECEF) of the receiver in the test process. The ground truth in ECEF has been set, the reference position in ECEF is \(-\)1,445,000 m in the \(X\)-axis direction, 6,150,000 m in the \(Y\)-axis direction, 180,000 m in the \(Z\)-axis direction. The ECEF coordinate given in this experiment is the positioning error vector subject to the reference position. The statistical results of Doppler frequency range (difference between maximum and minimum), maximum \(C/N_{0}\), minimum \(C/N_{0}\) and average \(C/N_{0}\) of six signals received by test receiver are shown in Table 1.  
Figures 7 and 8 show the change of Doppler frequency with time of the six signals received by test receiver. During the period of 4-184 s, spoofing signal and authentic signal affect receiver at the same time, and Doppler frequency of six signals fluctuates. According to the statistics during 0-200 s, the range of Doppler frequency is 87,900 Hz. During 184-200 s, code rate and carrier phase rate of spoofing signals change, and Doppler frequency of signals remains stable. Figure 8: Changes in Doppler frequency of SVID29, 30, 31 in experiment 1. Figure 9: Changes in \(C/N_{0}\) of SVID9, 14, 18 in experiment 1. Figure 11 shows the change of ECEF coordinate positioning results with time. During the period of 4-184 s, the spoofing signal and authentic signal affect the receiver at the same time. The range of ECEF three-dimensional coordinates is 12,260 m, 104,200 m and 10,180 m, respectively. The high-power spoofing signal causes a large fluctuation in the positioning results of receiver. During the period of 184-200 s, the corresponding spoofing signal begins to pull the positioning result stage, and the positioning result of the receiver is gradually pulled. The range of three-dimensional coordinates of ECEF is 213.5 m, 1848 m and 93.45 m, respectively, so the positioning result of the receiver has changed greatly. In the experiment, we have explained in the designed experimental steps.