[sdiy] Digital Bandpass Filters

[M.A. Koot]

> Labview ?!

Ah, no, I'm sorry. I'm using the NI Measurement Studio Package.
It contains a lot of routines which man can use in Visual Basic.
It also contains these Filter routines.

I guess I'll have to read the Norm some more intense for the requirements on
the lowest filters. But I would find it strange if it would be allowed to
have the lowest bands at such a major attenuation I now get. 

Thanks for the quick reply!

Cheers,
Michiel

> I've played with higer order filters in Labview recently, and they went
> crazy
> indeed. But I didn't try more than a few days, and I'm in no way a Labview
> expert. But I can confirm that with very high orders they don't do what
> would 
> be expected.
> 
> Anyway: you don't need high order filters for a 1/3 octave analyzer.
> 6th order filters should be well enough.
> 
> As for your extremely low (absolute) bandwidth on the lowest frequency
> bands, 
> don't worry: The required filter order depends (among other factors) on
> the 
> _relative_ bandwidth, i.e. bandwidth / center frequency. Doesn't look that
> bad 
> anymore, does it? Expect long settling times for such a low center
> frequency, 
> however.
> 
> 
> JH.
> 
> 
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> debitel.net Webmail
> 

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