Re: [Phys-l] software needed

[John Denker <jsd@av8n.com>]

Josh Gates-fac wrote:
> I'm looking for some free/cheap sound analysis software for class this
> year.  The only necessary requirements are:
> - record variable length samples from sound card
> - show waveform with time scale, pref. with autoscaling capability
> - FFT frequency spectrum generation
>
> That's it!  I find lots of stuff that's too expensive or has too many
> features and too complicated an interface to unleash on 9th graders - I'm
> really looking for a display something along the lines of LoggerPro from
> Vernier.

There are a number of free oscilloscope programs for the PC,
including some with spectrum-analyzer capability.
  http://www.google.com/search?q=pc+oscilloscope+spectrum+free+easy-to-use

Have you tried these?

If so, can you be more specific about which ones you have tried, and
in what ways they were unsatisfactory?

=================

It may be helpful to split the question into two parts.

As for plain old oscilloscope functions, it is fairly easy to get
something that is
  a) easy to use, and
  b) powerful enough to do what you want.


As for spectrum analyzers, I have never found one that was
  a) easy to use, and
  b) powerful enough to do what I wanted.

More commonly I've encountered ones that were *neither* easy to
use nor powerful enough.  More than once I've had to build custom
analysis systems.

I kinda suspect no "handy pocket version" exists, because the underlying
ideas are just too complicated ... although I would be delighted to be
proved wrong about this.

There's a lot more to a decent spectrum analyzer than just a call to the
FFT subroutine.  If you just have a button that performs an FFT, the
result is going to be ugly and misleading, and the students will wonder
why anybody would bother with such a thing.  At the other extreme, doing
a nice job requires lots of non-obvious fiddling.  Details available on
request. I don't know of any happy medium ... although I would be
delighted to hear about one.

Maybe if you had a very specific application in mind, you could rig up
an analyzer optimized for that application.  Perhaps if we heard more
about the intended application(s) better suggestions would be forthcoming.