On 2 Jul., 15:56, "Qingeng.Deng" <Qingeng.D...@[EMAIL PROTECTED]
> wrote:
> hello, everybody:
> =A0 =A0 =A0 I have one problem in do my master thesis, and need your
help.=
> The question is as follows:
> =A0 I have got the impulse response functions, the formulation of which
> is h(t) =3D u(t)exp(-(ln(t/tao)/sigma)^2), but i want to use a digital
> FIR filter with 7~8 taps or IIR filter with m zeros and n poles to
> simulate it. What should i do? Thanks for your helps.
What a wonderful impulse response! Where did you stumble onto this
jewel? It made its way right into my collection! In my first attempt I
couldn't compute its Fourier or Laplace transform but it sure looks
interesting.
Anycase, what frequency range to you have to simulate - what is the
ratio of the sampling period and tau? And what is the interesting
range for the sigma parameter? From the looks of it, you'll be needing
a bit more than just an 8 tap FIR to simulate this filter's action -
of course always depending on the required accuracy of the simulation.
The brute force approach might work (impules invariance method),
depending on sigma and your processing power - it clearly is a lowpass
filter, so the induced aliasing might not be that bad (depends on your
sampling frequency). Can you expand a bit further on the application?
Regards,
Andor
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