时空欠采样线性调频信号参数及其二维到达角联合估计
Parameter and 2-D AOA Estimation of LFM Sources with Spatio-Temporal Undersampling
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摘要: 针对宽频段(2-18GHz)内非平稳来波信号的参数估计和测向问题，提出一种时空欠采样线性调频信号参数与二维到达角联合估计方法。该方法首先用时域解线调方法估计调频斜率,然后在分数阶傅里叶变换(FRFT)域进行滤波，实现信号提取。利用参考阵元及其延时通道进行无模糊初始频率估计，通过构建FRFT波束空间阵列模型实现无模糊测向。数值仿真表明，该方法能够实现宽频段内多个线性调频信号的参数和二维到达角精确估计，在低信噪比下仍有较好的估计性能。Abstract: Time-Frequency parameter estimation and direction finding for nonstationary signals impinging on an antenna array over a wide frequency band (2~18GHz) is under in-vestigation, and a new method for parameter and 2-D Angle-Of-Arrival (AOA) estimation of spatio-temporal undersampled LFM sources is proposed in this paper. The proposed method uses time domain dechirp algorithm for chirp rates estimation. By filtering in the fractional Fourier domain, signals are extracted from the mixture of sources and noise. Un-ambiguous initial frequency estimates are obtained from the output of the reference element and its time delayed version, while 2-D AOA estimation is based on the array model in FRFT beamspace. Numerical simulations show that this method can deal with multiple LFM sources. Parameter and AOA estimation with high accuracy is available at low SNR.
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