# An Anti-Interference Method Based on Energy Residual Searching in GNSS Positioning Applications
## 5 Simulation and Results
in this paper effectively removes LFM interference and significantly improves GNSS receiver positioning accuracy. After applying the filtering process, there was a significant improvement in positioning accuracy. Before filtering, the standard deviation of latitude was 2.5943 m, longitude was 3.1719 m, and altitude was 4.1788 m. Following the filtering, the standard deviation of latitude decreased to 0.90069 m, longitude to 1.2805 m, and altitude to 2.3074 m, indicating a substantial enhancement in the precision of the positioning data. As demonstrated in Figure 5(b), after the removal of LFM interference, the positioning results from the GNSS receiver exhibited clear concentration, with substantial enhancement in positioning accuracy. As shown in Figure 7, the experimental parameters for the Monte Carlo simulations were set as follows: the C/N\({}_{0}\) of the useful GPS L1-C/A signal was configured to 40 dB-Hz, the JNR value of the sweeping interference was selected as 20 dB for the CAF evaluation, the sweeping period was established at 0.5 ms, and the coherent integration time was set to 2 ms. A total of 90,000 GNSS signal acquisition tests were conducted, to obtain the detection probability and false alarm probability under various signal reception environments. We observed that the receiver exhibited excellent acquisition performance in the absence of interference. However, the presence of LFM interference significantly diminished the probability of successfully capturing the signal compared to interference-free conditions. Furthermore, it can be noted that while the application of adaptive notch filtering technology enhances acquisition performance, and the interference mitigation capability of the Wigner-Ville distribution is somewhat superior, our proposed method demonstrated improved interference resilience compared to both adaptive notch filtering and the Wigner-Ville distribution. In Figure 8, we present the experimental parameters for the Monte Carlo simulations, where the signal's C/N\({}_{0}\) ranged from 35 to 45 dB-Hz, the JNR value of the sweeping interference was set to 2 dB, the sweeping period was 0.2 ms, and the coherent integration time was 1 ms. The SNR curve in Figure 8 illustrates the acquisition performance of the GNSS receiver in both interference-free and interference-affected conditions, while also comparing the effectiveness of our proposed method with the Wigner-Ville distribution and notch filtering algorithms, in terms of interference suppression. It is evident that the receiver demonstrated optimal acquisition performance in the absence of interference. However, the receiver's acquisition capability significantly declined when the received signal is subjected to interference. The use of adaptive notch filtering technology provided a gradual enhancement of the receiver's acquisition performance, albeit with limited effectiveness. In comparison, the Wigner-Ville distribution offered better mitigation of the sweeping interference; however, it remained constrained by the interference from the cross terms and failed to achieve optimal performance. Our proposed method demonstrated a  
Figure 6: Comparison of positioning accuracy. The coherent integration time was 1 ms, C/N0 = 40 dB-Hz, JNR = \(-4\) dB, on the building of the University of Texas at Austin: (**a**) positioning results before processing; (**b**) positioning results after processing. significant advantage over the previous two approaches, effectively minimizing the impact of sweeping interference to the greatest extent possible. Furthermore, to further validate the anti-jamming performance of the proposed method, we conducted tests in real-world scenarios. Considering that the active transmission of LFM signals may involve legal issues, we simulated the interference effects by combining the interference signals emitted from a jamming device with the actual GPS L1 signal, using a signal combiner.