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目前大多数FFT计算机是用输入——输出的互谱密度除以输入的功率谱来计算频率响应函数的估计的。此种估计受到输入端噪声的污染。人们用相干函数来检验污染的程度。然而,相干函数同时检验到输入、输出两端的噪声。文章提出另外两种计算频率响应函数的方法。一种能在共振区中取得精确的估计,另一种方法所受的污染只有现行方法的一半或更小一些,并打算用来同时估计偏度污染。
Most current FFT computers calculate the estimate of the frequency response function by dividing the input-output cross-spectral density by the input power spectrum. This estimation is contaminated by the input noise. People use coherence functions to test the degree of contamination. However, the coherence function also tests for noise on both the input and output. The article proposes two other methods of calculating the frequency response function. One can get accurate estimates in the resonance zone, and the other is only half as clean as the current method and is intended to be used to simultaneously estimate skew pollution.