時(shí)空欠采樣線性調(diào)頻信號(hào)參數(shù)及其二維到達(dá)角聯(lián)合估計(jì)
Parameter and 2-D AOA Estimation of LFM Sources with Spatio-Temporal Undersampling
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摘要: 針對(duì)寬頻段(2-18GHz)內(nèi)非平穩(wěn)來波信號(hào)的參數(shù)估計(jì)和測(cè)向問題，提出一種時(shí)空欠采樣線性調(diào)頻信號(hào)參數(shù)與二維到達(dá)角聯(lián)合估計(jì)方法。該方法首先用時(shí)域解線調(diào)方法估計(jì)調(diào)頻斜率,然后在分?jǐn)?shù)階傅里葉變換(FRFT)域進(jìn)行濾波，實(shí)現(xiàn)信號(hào)提取。利用參考陣元及其延時(shí)通道進(jìn)行無模糊初始頻率估計(jì)，通過構(gòu)建FRFT波束空間陣列模型實(shí)現(xiàn)無模糊測(cè)向。數(shù)值仿真表明，該方法能夠?qū)崿F(xiàn)寬頻段內(nèi)多個(gè)線性調(diào)頻信號(hào)的參數(shù)和二維到達(dá)角精確估計(jì)，在低信噪比下仍有較好的估計(jì)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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