Re: Data Acquisition

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

Screening real close to the lens will just reduce brightness, but won't
affect image quality much.  You can put the whole camera in a shielded box
and run the USB cable inside shielding too. I don't know that I would trust
the shielding on USB, per se...It's more designed to help meet Part 15 (and
I've spent the weekend turning on and off equipment all over the house
trying to find a fairly broadband emitter peaking at about 21 MHz with spurs
every 180 kHz)

If "I" had to do this, I'd use a regular video camera into a frame grabber,
rather than a USB cam.
Or, use one of the RS232 cameras around.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, January 19, 2004 4:56 PM
Subject: Re: Data Acquisition


 > Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>
 >
 > Hi Jim,
 >
 > Hehehe, You were way ahead of us ;-))
 >
 > I had a labcam on 20 feet (too much) of USB cable too.  But every time
 > anything would make a little spark, it all locked up.  It was very
 > susceptible to EMI.  In Dave's case, that may not be an issue.  But those
 > cameras and USB sure seem to hate sparks.
 >
 > Cheers,
 >
 >          Terry
 >
 > At 05:17 PM 1/19/2004, you wrote:
 > > > Hi,
 > > >
 > > > Don't forget, a meter can be set next to a clock and they can be
watched
 > > > with a camcorder.  If you already have the stuff, that costs zero.  If
you
 > > > have a video capture card or one of those webcam things (cheap now
too),
 > > > you can find free software out there to grab and store the image say
every
 > > > 15 seconds.  Might not impress NASA, but it sure is cheap, easy, and
just
 > > > as effective!
 > >
 > >Au contraire!  I used exactly this approach to monitor an antenna az/el
 > >pedestal out at NASA White Sands Test Facility. We had the pedestal and a
 > >battery powered clock in the video scene, and wrote a little VB
application
 > >to read the clock (since the hands are always in the same place, it's
easy)
 > >and generate a file that told when the pedestal moved.
 > >
 > >For a more current application of "video capture for data acquisition"
 > >consider the sundial on the Mars Rovers.
 > >
 > >The real hangup you have to watch out for is limited resolution and
contrast
 > >issues. You're not going to read a panel of LCD displays or analog dials
on
 > >a 320x240 webcam.  If you have dials with big fat pointers (like aircraft
 > >gauges) it works fairly well for trending.  The video scheme also works
 > >fairly well for things like a manometer panel fed from a pitot rake.
 >
 >