Patent Document ID: 4885708
Application ID: 07271879
Patent Status: 1

Claim One:
1. A frequency response function measuring apparatus for connection to an object to be measured, comprising: first address generating means for repeatedly generating a sequence of addresses in synchronism with a clock; second address generating means for generating a sequence of addresses in synchronism with the clock, while arbitrarily shifting the sequence of addresses every fixed period; first waveform generating means which has written therein a first multiple waveform containing desired analyzing frequency components and having opposite ends which are continuous to each other, the first multiple waveform being read out by the addresses generated by said first address generating means to generate a first analog excitation signal to be applied to the object to be measured; second waveform generating means which has written therein a second multiple waveform containing desired analyzing frequency components and having opposite ends which are continuous to each other, the second multiple waveform being read out by the addresses generated by said second address generating means to generate a second analog excitation signal to be applied to the object to be measured. Fourier transform means for extracting at least one frame of a predetermined numer of samples from each of the first and second analog excitation signals and a response signal from the object in a predetermined length of analysis every said fixed period, and for subjecting each frame of the extracted samples of the first and second excitation signals and the response signal to Fourier transform and then to calculation of elements of a cross spectral matrix every said fixed period; averaging means for sequentially averaging corresponding elements of the corresponding cross spectral matrices a predetermined number of times corresponding to the shifting of the sequence of addresses to obtain elements of an averaged cross spectral matrix; and computing means for computing a desired frequency response function from selected elements of the averaged cross spectral matrix calculated by said averaging means.