[sdiy] Filter Frequency response measurement ?

[Roy J. Tellason]

On Friday 27 July 2007 06:08, dj hohum wrote:
> Hi All,
>
> Is there an easy way to do this that I'm missing? Some sort of
> software that generates a sweep and looks at the output?
>
> My understanding of the process is that you use a ramp generator that
> sweeps the horizontal of my scope in XY mode and a voltage controlled
> sine wave generator at the same time. You feed the sine wave into the
> filter and feed the output of the filter into a detector, either peak
> or RMS? Then if you feed this into the scope you get a response in
> voltage. If you want Db, you need to feed it into a log amp prior to
> the scope X input.
>
> Alternatively, can you just feed noise into the filter and take an FFT
> of the output?
>
> Surely, there is either software to do this, or, a simple design that
> will save me the trouble of piecing it together and calibrating it.
> I'm not looking for high quality results, I just want to be able to
> tell at a glance what a circuit is doing while I'm working on it.

You might take a look at a software package called baudline.  Looks pretty 
nifty,  from what I can see on their site...

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