[Scilab-users] Identifying parameters of a multy frequency damped oscillation

[roger.cormier at ncf.ca]

Would you consider an ARMA model of the signal? You need to chose the order of the system so a bit of experimenting is needed. Just an idea.

Regards,

Roger.


___________________________
Dr. Roger Cormier, P.Eng.
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Le lun. 7 sept. 2015 à 08:26, Jens Simon Strom a écrit :

> Hi Scilab users,
> 
> I want to analyse a microphone recording of the sound of a bell or gong. Given ia the equidistantly sampled sound pressure y(t) after a stroke for 10 s
> .
> 
> 
> The ansatz
>  
> 
> 
> y=sum(  A_i*exp(-d_i*t))*cos(2*%pi*f_i+alpha_i)  )
>   for i=1,2,...5 or more
> 
> 
> is assumed to approximate the signal where A_i, d_i, f_i, and alpha_i are the unknown amplitudes, danping factors, frequencies, and phase angles of y. The analysis may be restricted to the lowest 5 frequencies fi.
> Does Scilab offer a method for this? FFT seems not to be adequate because the signal is aperiodic (silence after 10 s).
> Is nonlinear regression (with which I'm fmiliar) a promising way. The lowest frequencies can probably be concluded from a short time DFT where damping is 
> negligible.
> Kind regards
> Jens
> 
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