I read this mail from AMSAT list and I thought in this list someone could help. ----- Original Message ----- From: Bob Bruninga <bruninga@usna.edu> To: <amsat-bb@AMSAT.Org> Sent: Friday, April 27, 2001 9:01 PM Subject: [amsat-bb] 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 > > ---- > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA. > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Sat Apr 28 2001 - 19:27:50 PDT