OkeeDokee; thanks.


> Mark Skeels
> Engineer
> Competition Electronics, Inc.
> TEL: 815-874-8001
> FAX: 815-874-8181
> www.competitionelectronics.com
> Mark E. Skeels wrote:
>>      * I don't know much about DSP. Could you explain to me what you
>>        mean when you say "a true impulse is of course impossible"?
> This is straight from linear systems and signal processing theory, which =
I
> have neither time, inclination, nor space to try to explain here.
>
> Look up impulse or "gamma function", and you'll see it's a function defin=
ed
> to have zero duration but a area of 1.  That's rather hard to do in
> practise.  Usually you make due with short enough for the highest frequen=
cy
> of interest and adjust the amplitude or compensate for it in the math as
> appropriate.  Another trick is to use a step function, which is generally=
 a
> little easier to realize well enough.  Since a step is the integral of a
> impulse, the system response you get is the integral of the impulse
> response.  Math can convert that to the impulse response, but since it's
> taking the derivative is susceptible to noise.
>
>>        Maybe another way to
>>        approach it is to sweep through the relevant part of the audio
>>        band and note the amplitude at various levels?
> Right, as I said in my original post on this thread.
>
>>      * Let's say one wanted to apply some kind of 'impulse" to the
>>        room....how could you go about that? Thump on the wall? Run some
>>        kind of signal through a speaker or some other kind of
>>        transducer? What would be the character of that "impulse" ?
> A thump on the wall will be nowhere near good enough for the purpose, and
> will be in the wrong location too.  You can probably put a short pulse in=
to
> a sufficiently high frequency transducer to get a good enough impulse for
> the purpose.  However, there are lots of things that can cause practise t=
o
> deviate from theory with this method.  If you have to ask, it's probably =
not
> the right approach.
>
>
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