"Randy Yates" wrote in message
ow (Goofball_star_dot_etal) writes:
On Wed, 11 Aug 2004 15:28:45 -0400, "Arny Krueger"
wrote:
"Goofball_star_dot_etal" wrote in message
On Wed, 11 Aug 2004 02:57:26 GMT, Randy Yates
wrote:
An accelerometer, a la Velodyne?
And those who are not asleep will note that this is a very good
solution from an experimental point of view. Points to those that
say why.
It gives you acelleration, forthwith.
Integrate it (essentially pass it through a low pass filter) once
and you get velocity.
Integrate it again and you get position.
Every time you integrate it, a lot of spurious noise gets low-pass
filtered @ 6 dB/octave.
Yes, and that's a good thing(TM).
Agreed.
OK, 2 points but remember what Svante said. .
I can't find that post...
and there is more. . .
Think "one variable at a time" and "how should we record and process
the accelerometer data?"
I thought I covered that.
What's the bandwidth of an accelerometer signal when stuck on a speaker
cone?
Depends on the type of acellerometer. The ones commonly used with subwoofers
have dominant poles up in the 100's of Hz. The pole is due to the mass of
the acellerometer and the compliance of the mounting. Acellerometers used
this way do somewhat change the dynamics of the cone.
No problemo at 50 Hz.
The *pro* methodology involves a laser and $$$$. The Dumax machine does it
that way.
Could you use a sound card input to digitize it?
No doubt, with suitable preamplification.
Now, I'm thinking about calibrating the accelerometer on the cone.