 | | | | | | |
| |
|
In lugnet.robotics, Claude Baumann wrote:
> ...you tried to maintain the sound pressure constant.
Since I was doing this all manually, it was by far the easiest. I realized that
a better way would be to vary the signal generator level at each frequency, but
often when trying that I simple "maxed out" the reported level from the sound
sensor at some frequency, and wanted to do that as little as possible.
> we were amazed to see that around 3kHz, the sound sometimes
> has to be louder, sometimes weaker, in order to maintain the
> constant 20 NXT-dBA. We sweeped over the range and the value
> droped and grew at neighbour frequencies.
That sounds like resonance. Perhaps in the sensor response, but at 3 kHz the
wavelength is down around 10 cm, meaning a half-wavelength at 5 cm is getting
very close to the physical dimensions of the sensor. Did you check for physical
resonance effects, perhaps within the casework?
> This leaves us puzzled. It would be a great thing, if someone
> verified this.
I'd love to, but don't have the signal generator right now. I'm very tempted to
get something like this:
http://www.pasco.com/featured-products/xplorer-glx/index.cfm
As it would satisfy nearly all of my datalogging needs when they go beyond the
NXT (higher resolution).
--
Brian Davis
| | | | | | | | | | | | | | |
> That sounds like resonance. Perhaps in the sensor response, but at 3 kHz the
> wavelength is down around 10 cm, meaning a half-wavelength at 5 cm is getting
> very close to the physical dimensions of the sensor. Did you check for physical
> resonance effects, perhaps within the casework?
Excellent suggestion!!! We'll open one sensor and try once again.
> ...I'd love to, but don't have the signal generator right now. I'm very tempted
> to get something like this:
> http://www.pasco.com/featured-products/xplorer-glx/index.cfm
B.t.w. Vernier also has a remarkable device:
http://www.vernier.com/labquest/
Someone else interested in repeating the experiment? Philo?
Claude
P.S. I added a graph to the page, where the sound pressure is maintained
constant.
| | | | | | | | | | | | | | | | | |
> Someone else interested in repeating the experiment? Philo?
I would be interested, but I have no audio equipment (apart from a function
generator)
Very interesting data BTW!
Philo
| | | | | | | | | | | | | | | | | |
In lugnet.robotics, Claude Baumann wrote:
> > ...I'd love to, but don't have the signal generator right
> > now. I'm very tempted to get something like this:
>
> > http://www.pasco.com/featured-products/xplorer-glx/index.cfm
>
> B.t.w. Vernier also has a remarkable device:
>
> http://www.vernier.com/labquest/
I've looked at that, but honestly got interested in the Pasco product first just
due to who's catalog arrived at my house first. They look almost identical in
functionality except the LabQuest has a stylus and more memory, while the
XplorerGLX has I2C sensors (or seomthing like them; it seems they transmit
digital information back the main unit, while the Vernier sensors are analog and
AtoD is done on the main unit). Is that correct? Do you use a LabQuest and do
you have any more information, reviews, comments etc about it? It's not like
this is a product reviewed by Consumers Reports or something, so I'm finding it
hard to get 1st-hand knowledge.
--
Brian Davis
| | | | | | | | | | | | | | | | |
> I've looked at that, but honestly got interested in the Pasco product first just
> due to who's catalog arrived at my house first. They look almost identical in
> functionality except the LabQuest has a stylus and more memory, while the
> XplorerGLX has I2C sensors (or seomthing like them; it seems they transmit
> digital information back the main unit, while the Vernier sensors are analog and
> AtoD is done on the main unit). Is that correct? Do you use a LabQuest and do
> you have any more information, reviews, comments etc about it? It's not like
> this is a product reviewed by Consumers Reports or something, so I'm finding it
> hard to get 1st-hand knowledge.
Nop, I have seen it. I will try to get more information about it.
| | | | | | |
