170828 LFM信号时域加窗与频域加窗.pdf

Time and Frequency Domain Windowing of LFM Pulses Mark A. Richards September 29, 2006 1 Frequency Domain Windowing of LFM Waveforms in Fundamentals of Radar Signal Processing Section 4.7.1 of [1] discusses the reduction of time (range) sidelobes in the output of the linear FM (LFM) waveform matched filter using weighting in the frequency domain. The approach is to form a modified filter frequency response H ′ (F ) = w (F ) X ∗ (F ) , (1) where w(F) is a window function (Hamming, Kaiser, Taylor, etc.), instead of the usual * matched filter choice H(F) = X (F). By performing the matched filtering in the frequency domain, we can combine the matched filter operation with the windowing to reduce the required computation. A block diagram of one way to arrange the flow of operations is shown in Figure 1. This diagram shows the window applied to the filter frequency response before the actual filtering step. This has the advantage of allowing the windowing to be done off-line, i.e. not in real time. We could just as well apply the window to the product of the signal and matched filter frequency responses. The end result at the output would be identical, but the windowing would have to be repeated every time there was a new signal to filter, and in real time. receivedreceived outputoutput DFTDFT IDFTIDFT signalsignal signalsignal windowwindow DFTDFT