On Mon, 25 Aug 2008 15:25:28 GMT, sal2 <sal2@[EMAIL PROTECTED]
> wrote:
>Greetings All
>
>Can someone recommend a good software program that can do audio frequency
>sweeps through the computer sound card, without me having to type in and
>test each frequency separately.
>
>Example: Play 10hz to 20,000hz incrementing by 1 Hz over 15 seconds time
>span
>
My Daqarta software can do that with ease. Download (see sig) and install
it.
(It's absolutely FREE, forever, if you only need the signal gnerator.)
When it starts up, it will create a 400 Hz sine by default when you toggle
Generator on. To change that, click on Waveform Controls and then Sweep.
In the Sweep dialog you can set Start and End frequencies, and Length in
samples
or seconds.
That will give a smooth continuous sweep, lasting Length duration, which
you can
set to Linear or Exponential. To get steps, click the Stairs button. If
you
have set Start to 10 Hz and End to 20000, the Stairs window will show
19990
steps. However, in Stairs mode the Length value is the time spent at
*each*
step, so in your case you would set it to 15/19990 = 750 usec. (You can
enter
'750u' instead of '0.000750' for this.)
Note, however, that 750 usec is not a lot of time to hold at a single
frequency... only 36 samples at 48000 samples per sec. You might be
better off
with a smooth sweep in this case. If you are going to use this to measure
a
frequency response, make sure your analyzer can respond adequately.
If you use Daqarta for this (see below), you should set the Spectrum
Window
to Flat Top. But there is a much better way, which is to use no window
function
but set Daqarta so that it only steps to each spectral line. This insures
that
the spectrum will have no spectral leakage. See the Frequency Sweep Stairs
topic
in Help (right-click on the Stairs control), or at
<http://www.daqarta.com/dw_ee0s.htm>.
Note that although the Generator is free, if you want to analyze input
signals
after the 30-day/30-session trial period you will need to buy a license
(US$29
for personal use).
If you have any questions about Daqarta, or frequency response
measurement, or
anything related to data acquisition, please feel free to use the contact
form
on the site.
Best regards,
Bob Masta
DAQARTA v4.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!
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