Hello,
From a time domain response and excitation signal, I'm trying to compute and plot an FRF function. I've tried using both FFT and the built-in function modalfrf to compute the FRF. However the resulting FRFs look slightly different and differ greatly in magnitude. Notice how the modalfrf curve has a somewhat "downhill" look (orange one) while the one I computed using my code (blue) looks more "flat". Does anyone know what might be the issue here?
%% My FRF code using FFT
tempx=fft(a5);tempf=fft(F);x1=(tempx);f1=(tempf);L=length(x1)/2;X=x1(1:L);Fu=f1(1:L);FRF=abs(X./Fu);freq=linspace(0,Nq,length(FRF));figureloglog(freq,FRF);grid onxlabel('Frecuencia (Hz)')ylabel('FRF (dB)')xlim([3 70])ylim([yinf ysup])%% Using modalfrf function
[FRF,f]=modalfrf(F,a5,Fs,hann(50000),0.1*50000);xlim([3 70])FRF=abs(FRF);loglog(f,FRF,'Linewidth', 1)xlim([3 70])ylim([yinf ysup])xlabel("Frecuencia (Hz)")ylabel("FRF (g/N)")
Thank you in advance.
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