跳頻及頻域分集多輸入多輸出雷達於假目標干擾下之目標偵測和定位

Abstract

本論文提出一種新型 FH-LFM-FD-MIMO 雷達系統來檢測和定位真實目標，同時抑制虛假目標干擾信號。由發射陣列發射經過載波頻率優化的線性調頻 (LFM) 脈衝，來實現頻率分集多輸入多輸出（FD-MIMO）和跳頻（FH）方法。結合粒子群優化（PSO）算法和排序值（ROV）映射來生成頻率分集 (FD) 碼，以增強干擾抑制性能為目標，再依據頻率分集 (FD) 碼設定所有發射陣列單元的頻率偏移。應用特定的FD碼來實現跳頻（FH）方法，脈衝重複間隔可抑制頻域和空間域中的干擾信號，接收器檢測到具匹配 FD 代碼的目標回波，同時抑制具不匹配FD碼的假目標干擾信號。再使用第二種 PSO 算法優化聚焦範圍波束形成向量，以實現低旁瓣的聚焦響應。檢測到目標後，應用二維最小方差無失真響應（2D-MVDR）以更精確地定位目標。提出一種二元積分檢測方法來增強嚴重干擾條件下的檢測性能。模擬結果驗證了所提出的FH-LFM-FD-MIMO雷達系統與傳統方法相比可以將輸出信號干擾加噪聲比（SJNR）提高20 dB以上，在給定誤報率下獲得更高的檢測機率，並提高定位精確度。

A novel FH-LFM-FD-MIMO radar system is proposed to detect and localize true targets while suppressing false-target jamming signals. Linear frequency modulated (LFM) pulses are transmitted by a transmit array, with the carrier frequencies optimized to implement frequency-diverse multiple-input-multiple-output (FD-MIMO) and frequency-hopping (FH) schemes. The frequency offsets at all the transmit-array elements are represented as a frequency-diverse (FD) code, which is generated by combining a particle swarm optimization (PSO) algorithm and a rank-order-value (ROV) mapping to enhance the jamming suppression performance. The frequency-hopping (FH) scheme is implemented by applying specific FD codes in different pulse repetition intervals to suppress jamming signals in both frequency domain and spatial domain. The target echoes carrying matched FD code are detected at the receiver, while the false-target jamming signals carrying mismatched FD codes are suppressed. A spotlight response with low sidelobe level is achieved by optimizing the spotlight-range beamforming vector with a second PSO algorithm. After a target is detected, a two-dimensional minimum-variance distortionless response (2D-MVDR) is applied to pinpoint the target with higher precision. A binary integration detection scheme is proposed to enhance the detection performance under more severe jamming condition. The simulation results verify that the proposed FH-LFM-FD-MIMO radar system can increase the output signal-to-jamming-plus-noise ratio (SJNR) by more than 20 dB compared to conventional approaches, acquiring higher probability of detection under constant false alarm rate and enhancing the localization precision.