- 學位論文
降低都普勒效應之格雷互補對應用
The Application of Golay Complementary Pairs in Mitigating The Doppler Effect
摘要
格雷互補序列對擁有良好的自相關特性，可以使用相位編碼(phase coded)的方式，將格雷互補對應用在雷達上，使雷達較能承受訊號衰減及雜訊的影響，並且增加雷達偵測目標物距離之解析度(resolution)。實際應用因雷達與所偵測目標物之間的相對運動，造成都普勒效應使訊號頻率產生漂移，直接影響接收端解調後之混淆函數，使旁峰與頻率漂移成正比變化無法抑制，使格雷互補對應用的成效不理想。 本篇論文延伸2008年Pezeshki、Calderbank、Moran和Howard所提出的方法，探討如何抑制格雷互補對應用於雷達的都普勒效應。文獻提出將二位元格雷互補對傳送之順序滿足PTM(Prouhet-Thue-Morse)序列，可有效降低都普勒效應對雷達解調後之混淆函數的影響。我們採用將二位元格雷互補對以複數組合，發射時以調變正交載波的方式同時傳送，並且將一個時段同時傳送格雷互補對之方式，與一個時段僅傳送一個二位元格雷互補序列比較，可使雷達僅接收一個回波即可得到一對格雷互補序列，以降低回波部份接收時之混淆函數旁峰，使格雷互補對之特性充分發揮。我們採用更接近實際狀況的連續遞增相位描述都普勒效應，並測試多目標產生的重疊多回波偵測性能。模擬結果顯示雷達傳送複數組合的格雷互補對，在多目標回波重疊及雜訊嚴重時，仍可以正確的分辨目標物。
並列摘要
Golay complementary sequence pairs have fine auto correlation properties. The application of Golay complementary pairs in radar using phrase-coded method improves radar’s tolerance of fading and noise and improves the resolution in object distance. The relative motion between radar and its detected object causes “Doppler effect” , which leads to signal frequency shift. In actual applications, This increases the sidelobe levels of the ambiguity function and reduces the performance of Golay pairs in radar ranging. This thesis extends the methods presented by Pezeshki, Calderbank, Moran, and Howard in 2008, and discusses how Golay Complementary pairs can be used in radar while reducing the Doppler Effect. Pezehki et al showed that when binary Golay complementary pairs are sent according to the PTM (Prouhet-Thue-Morse) sequence, the influences of Doppler effect can be effectively reduced. We use a different transmission method where binary Golay complementary pairs are sent simultaneously on the inphase and quadrature parts of the subcarrier, and compare the performance with existing method. Using our method, the radar obtains a pair of Golay sequences from only one echo, which reduces the ambiguity function sidelobes when the reflected signals are partially received, and fully exploits the property of Golay pairs. We also adopt continuously increasing phase which better describes the Doppler Effect, and test the performance with multiple overlapping echoes from multiple objects. Simulations reveal that the radar can recognize the objects while sending Golay Complementary pairs using our method with multiple overlapping echoes and under severe noise.