Sound Blaster as Data Aquisition

[Rodney Pratt]

On Mon, 19 Feb 1996 18:50:21 +1100, you wrote:

>> run the dc thru a voltage to frequency convertor first, then digitize with
>> the sound blaster.
>> you could then save the result as a wave file (am assuming PC with windows
>> vs. eg mac)
>> the format of a wave file is probably on the internet "somewhere" and
>> "somewhere" on my hard
>> disk is a MATLAB file that can read it as an array of numbers that can be
>> FFTed, graphed, displayed
>> or whatever. (or run the pitch thru a lookup table to reverse the v2f
>> converter.)
>> Matt Smith
>> masmith089 at qnet.com
>> Mailer Eudora 1.5.2
>
>What kind of accuracy can you get (do you expect) from such a system ??
>
>I would think it would not be as good as direct DC sampling.  
>Any comments from anyone who has tried ???
>
>
>-- 
I know of someone who has used this approach successfully on a Kart to
log RPM. They used a portable tape recorder to record the output of a
magnetic pickup (directly in the microphone input) mounted to detect
RPM from a geared drive wheel. They then played this back into a
Soundblaster and wrote some software to analyse the .WAV file and
count zero-crossings, and hence producing  a plot of RPM vs time.

The magnetic pickup is perfect for this application as it produces a
nice sine wave output (ie no DC). It may also be suitable for other
frequency output type devices (ie. MAF sensors).

A cheap data logging alternative!!!!!!
Cheers,

Rodney Pratt                       rpratt at senet.com.au