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Date: | Thu, 8 Mar 2001 20:09:34 -0600 |
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I don't know how to contact anybody with that project,
but this kind of demonstration is a good example of how graphical
representation of quantitative data can be useful to people who
are blind as well as everybody else for that matter.
When we think of graphics, we think of diagrams and
pictures on paper or on a screen, but that is just one form of
numerical representation. Anybody who has ever played with a
light probe or one of those tuning devices that used to be a lot
more common than now has used a form of symbolic representation
of quantitative data without even thinking about it. If you can
convert any numerical value to a musical pitch or volume, you are
using a symbolic representation of a quantity and you are limited
only by your imagination as to what you might do with that
representation.
The scientists working on the Solar project simply made
something that is kind of hard to understand more clear. By
converting the very slow oscillations of the Sun in to a string
of digital samples and speeding them up a whole bunch, they allow
people to understand that the Sun usually flickers with a rhythm
that is surprisingly regular except for when Solar flares and
such disturb the regular motion.
The Sun basically hums most of the time. If you connect a photo
cell to an audio amplifier and turn on a lamp that is plugged in
to a wall socket, you will hear a bit of a hum at your power line
frequency if the lamp is incandescent and you will hear a much
louder hum if the lamp is fluorescent. The hum is usually twice
the power line frequency because the light gets brighter on each
half-cycle. With an incandescent bulb, the filament doesn't cool
down much between half-cycles so the range between full
brightness and the lesser brightness between half-cycles is not
very much, but it is enough to generate a ripple on the basically
DC output of a photo cell. This is exactly what the Sun is doing
although for totally different reasons.
The fluorescent lamp basically goes out between half
cycles so it actually strobes at twice the line frequency.
That's why you get a bit hum with one of those.
I guess this is enough for now, but this kind of stuff
goes right to the core of why amateur radio and technology are so
much fun. I suggest that those of you who like to tinker with
electronics get a photo cell and connect it to an amplifier and
stick that photo cell up to every light source you can. You'll
be surprised what you hear.
The photo cell can be either a photo diode or photo
transistor, but you might want to stay away from the light
Dependant resistor type cells for this kind of experimentation
because they are slow and you might miss higher frequency
variations in the light source. The only thing about silicon
photo cells is that they respond to infrared and do not respond
very well to blue and violet light.
Back to your question, I believe that NASA has a public
information office that deals with press releases about various
projects and can probably get you going in the right direction.
This may be part of the SOHO project that deals with the orbiting
Solar Observatory.
Martin McCormick WB5AGZ Stillwater, OK
OSU Center for Computing and Information Services Data Communications Group
Jim Stevenson writes:
>Do you know how to find out and contact those scientists?
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