信号相关性与DOA估计

窄带波达方向(DOA)估计模型中,相干信号的问题很容易引起混淆。一些文献简单地认为频率不同的信号是不相干的,而频率相同的信号就是相干信号。因此,在建立不相干信号的DOA估计模型时,采用不同中心频率的信号,而使用的方向矩阵却采用同一个信号频率,该文提出,当信号中心频率不同时,应采用各自相应的频率来建立方向矩阵。其DOA估计应采用宽带信号的DOA估计方法,也就是应该对不同的频率进行聚焦。而采用同一个频率来建立的方向矩阵恰好同聚焦后的信号模型相同,因此,其估计结果也就是正确的。但这样的信号模型与事实并不相符。该文严格按照相干信号的定义证明了只有频率和初始相位都相同的窄带信号才是相干信号,最后通过计算机仿真验证了这一点。

Signal Correlation and DOA Estimation

In the model of Direction-Of-Arrival (DOA) estimation of narrowband signals, the concept of coherent signals seem more confused. In some published references, the signals of different frequency were simply considered as incoherent, whereas those of same frequency as coherent signals. So, those publications adopted the signals of different frequency to build the DOA estimation model of incoherent signals but the same center frequency in its directional matrix. This is considered unadvisable in this paper. If the center frequencies of the signals are different, the directional matrix should be built with correspond frequency of each signal source. The DOA should be estimated by the method for wideband signals, i.e., the different frequency should be gathered. The directional matrix built with the same center frequency is fitly the same as that of the gathered model. In result, its estimation result is correct, but the signal model does not match the fact. According to the strict definition of coherent signal, this paper proves that only the signals of the same frequency and original phase are coherent. Our conclusion is validated by computer simulation.