全球定位系統(GPS)提供精確的位置、速度與時間的資訊,使用在民用和軍事的應用中是非常有用的。由於展頻本身具抗干擾性,全球導航衛星系統(GNSS)可利用展頻碼的程序增益(PG),將小功率的干擾信號予以壓制,但是當干擾源功率增大,而超過程序增益時,此時將導致接收機之同步迴路發生信號處理失鎖,而無法接收衛星訊號,因此GPS之干擾抑制為不可忽略之話題。本研究主要為設計高效能之全球導航衛星系統之抗干擾系統,以自適應濾波器為架構來預測與實現即時窄頻帶干擾抑制之功能。採用gLab-G軟體產生導航與干擾信號,取代硬體GPS接收機,使用傳統的正歸化最小均方(NLMS)方法與歸屬函數集濾波器(SMF)來抑制連續波的干擾。模擬結果從20dB至50dB,說明所提出的方法可以提供更好的干擾與雜訊比值(INR)之抗干擾性能評估,透過大量的模擬運算,最後可得到均方誤差(MSPE)與信號雜訊比(SNR)之比較圖。
The global positioning system (GPS) provides accurate positioning and timing information that is useful in various civil and military applications. The adaptive filtering predictor for GPS jamming suppression applications is proposed. This research uses the gLab-G software to substitute for the hardware receiver to record the GPS signal waveform. The normalized least-mean-square (NLMS) and set-membership filtering methods are employed for continuous wave interference suppression. Simulation results reveal that our proposed methods can provide the better performances when the interference-to-noise ratios (INR) are varied from 20 to 50 dB. The anti-jamming performances are evaluated via extensive simulation by computing mean squared prediction error (MSPE) and signal-to-noise ratio (SNR) improvements.