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Optical COmms experiment



Can someone compute the optical visibility of a 3 Watt lightbulb from 500
miles up?

We are going to put a 3 Watt radiator (resistor) on our PCsat to see if we
get about 8 degrees of cooling by radiating away excess solar/electrical
power.  It could just as easily be a lightbulb on the bottom of the
satellite.  At night, occassionally, we could blink it just for fun.

Can somone compute the stellar magnitude of this to see if it is worth
doing with a light bulb?  Assume only .3 Watts is actually in the visual
wavelengths.

Or if it is mildly possible, then we could go to bright LEDs and improve
the visual efficiency (WHat is the efficiency of an LED?  I assumed 10%
for an incandescent bulb? Might be closer to 5?)

Oh yes, assume a 90 degree directivity...(or more) or about say 3 dB of
transmit "antenna" gain...  And do power LED's generate RF noise?  I
thought all forward biased diodes generate noise to some degree?)

de WB4APR@amsat.org, Bob

PCsat Design        http://web.usna.navy.mil/~bruninga/pcsat.html

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