sound measurement

[Dave Jones]

Hey folks. I need to buy a sound measurement setup for my day job in robotics. We need to record and analyze the resonant modes of a robot. The resonances can be from around a couple of kHz down to subsonic. I figure you folks can point me in the right direction. I think I may already have everything I need except for microphone and preamp, but software suggestions are welcome too.

Of course, if the equipment and software can also be used for measuring loudspeakers, I wouldn't mind. :-)

[tschrama]

I would suggest using a electret microphone element, (panasomic from Digikey?). There are plenty of website arround that explain the design of a simple electret-based microphone, these can measure down to 10 Hz at least.

For lowest self-noise I've used
1] a bootstrapped load through a buffer, can be opamp or FET or BJT
2] a cascode to supply a steady 2 or 3 volt or so

Preamp can be any simple opamp configuration. Opamp noise level are not significant at this stage anymore.

For analysing you could use a software/freeware realtime spectroscoop. Search the forum, there are some excellent freeware programs.

Goodluck,
Thus

[Dave Jones]

Originally posted by tschrama
I would suggest using a electret microphone element, (panasomic from Digikey?). There are plenty of website arround that explain the design of a simple electret-based microphone, these can measure down to 10 Hz at least.

For lowest self-noise I've used
1] a bootstrapped load through a buffer, can be opamp or FET or BJT
2] a cascode to supply a steady 2 or 3 volt or so

Preamp can be any simple opamp configuration. Opamp noise level are not significant at this stage anymore.

For analysing you could use a software/freeware realtime spectroscoop. Search the forum, there are some excellent freeware programs.

Goodluck,
Thus

Could you elaborate? I don't understand either 1] or 2]. ... and I suppose "cascode" should be "cascade" and "spectroscoop" should be "spectroscope", no?

I didn't plan on using a realtime analyzer. I thought we would capture some raw data then analyze it after the fact.

[JOE DIRT®]

Dave take a look at this http://www.ascrents.com/pages/asc_noise_sound_meas.htm

I have one for sale

DIRT®

[MazzPotential]

You're statement:
We need to record and analyze the resonant modes of a robot

What is it that you want to measure?
1) the soundwaves in free-air produced by the robot. Frequency and Sound level.........
2) the resonance within the robot structure itself? e.g. vibrations in the cast/metal structure. Just frequency

Then again..... what is your goal. Pinpointing the resonance frequencies and ultimately alter the design wihtout resonances?

Just curious


Mazz.