[sdiy] Soundcard spectrum analyzer?

[Andre Majorel]

On 2008-05-08 08:48 +0200, JH. wrote:

> I'm looking for something to measure highly resonant filters,
> and I'm not sure if something that's aiming for the Audio / HiFi
> market is good enough, with short chirp signals and all.
> I'd feel more confident with something that sweeps very slowly,
> and measures with a small bandwidth filter - or whatever the
> equivalent in the digital domain would be.

Are you sure you want a BPF on the input ? Having the noise and
distortion products lumped together with the signal is not ideal
but isn't that more useful than not seeing them at all ?

If the filter under test is resonant, it will ring at Fc even if
the input frequency is far from Fc. A BPF will make the FUT appear
more selective than it really is.

I think. :-)

-- 
André Majorel <URL:http://www.teaser.fr/~amajorel/>
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