[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

PCsat Optical Comms Experiment



In conjunction with the Leonids meteor show, this may be a good time for
the first test of the Optical Comms experiment on PCsat.

PCsat has 80 standard red LEDs on the side facing the earth in the
horthern hemmisphere.  We can turn them on to see if anyone can see them.
This takes a good 50% of our power budget and so they can only be on for a
few minutes, so this will only be over the east coast and only one pass
which appears to be about 930 PM on Saturday night the 17th of Nov.

This is not the optimum time relative to  power budget, but it is an
opportunity when more people will be watching.  When I get to work
tomorrow and have a new set of Keps, I will nail down the exact time and
path over the usa.  So this is only a heads up...

We have not done a detailed analysis, but with 3 watts of DC power going
into the LEDs, some have estimated a magnitude 5 or 6 straight down
(barely visible with eyeball) and maybe a mag 8 off to the side
(binocluars).  ANy other estimates are welcome.  We have no pedigree on
the LEDS other than "standard red leds"...

PCsat appears to be spinning at about 1/4 RPM (exact attitude unknown)
so for any given viewer, you will only see the narrow field of view (about
30 degrees) occassionally (if at all), but someone somewhere should get a
straight shot at some time...

We may cycle the LEDS on and off at about a few second rate to save
power, this is TBD.  Even if this test fails to be seen, we will conduct
the test again later in the month when the optimum power is available.
That orbit is one that occurs just after dark, and just after PCsat enters
eclipse.  At that point the batteries are fully charged and so we get
maximum power to the LEDS.

The LEDS have a fail-safe turn-on circuit that will only allow them to
conduct current when the battery voltage is above 1.25 volts per cell
and this only occurs while the batteries are on charge (in the sun) nd
just afterwards...  So we must pick an orbit when the satelltie just
enters eclipse while in view of the command station (on the east coast)...
2000 EST on the 24th might be such a date.  More later...

However, Since I will be out in the field camping on the 17th with the
kids, in a dark area for the Leonids, I figured why not go ahead and see
what we can see now too...

de WB4APR@amsat.org, Bob

PCsat WEB  page     http://www.ew.usna.edu/~bruninga/pcsat.html
ISS-APRS FAQ:       http://www.ew.usna.edu/~bruninga/iss-faq.html
CUBESAT Designs     http://www.ew.usna.edu/~bruninga/cubesat.html
APRS LIVE pages     http://www.ew.usna.edu/~bruninga/aprs.html
APRS SATELLITES     http://www.ew.usna.edu/~bruninga/astars.html
MIM/Mic-E/Mic-Lite  http://www.toad.net/~wclement/bruninga/mic-lite.html


----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home