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PCsat's first day. Success!



AMSAT Friends throughout the world!

As the last pass over Annapolis ends, we are humbled at all the great
effort all around the world that all of you made to feed us live data as
PCsat took to the skies.  We are sorry that we might not get to
acknowledge everyone who contributed, but we saved EVERYthing and will
take days to sort it all out.  But as long as the batteries are up, we
are happy!

PCsat consists of two duplicate KPC-9612 TNC's transmitters and receivers
(and no other CPU).  It was launched in SAFE mode with both TNC's
crossconnected to both transmitters for redundancy.  On the first pass
over our Maryland USA ground station, we got side B set to normal mode,
all timers reset, and a status loaded.  Ground TNC problems plagued us for
the next two passes.

After two passes out of range north of us, we saw good battery charge from
all of your reports around the world, so we began the last pass period (3
passes) by turning on the GPS.  But we did not get TLE's loaded in time,
so that orbit was lost because the GPS had no clue where it was.  On the
next pass, we got the TLE's loaded, but post-pass analysis revealed that
voltage was droping to the point of GPS reset and so, the GPS was on/off
cycling while in eclipse, never being on for more than 20 seconds.  Not
enough time for a fix.  (Our eclipse's are now 15 minutes long).

The GPS is a negative power budget item which we can only balance when we
are in full sun, and that will not occur for several weeks, but we did
want to try an on-orbit check out of the GPS commanding.  As PCsat
approached on the last pass of today, we shut it down, and left PCsat in
"normal" telemetry beacon mode.

Please watch it, but please keep off the uplinks until we get it all
loaded...  Thanks.  And also thank  you all again for your data and your
patience!

As we go get some much needed sleep, there are some things you can look
for by eye:

1) If the STATUS packet ever loses the ">DDHHMMz..." time stamp then it
has experienced a reset and is back in safe mode.  The date-time stamp
above was the last time we reset the 72 hour fail safe timer.

2) If the battery ever drops below 14.4 volts.  You can see that by eye
in one-out-of-every 4 telemetry packets.  The packets end in "...,xyNN,1"
where the NN is the "frame counter".  The voltages are always the first
two analog values (of 5) in the frames ending in "...,xy11,1" and they are
pretty close to being in 10ths of a volt.  Thus the frame below shows A and B
battery voltages of about 16.1 and 15.8 respectively...

    T#456,161,158,ccc,ddd,eee,abcdefgh,xyNN,z

4) The "eee" value is always 213 if the bus voltage remains at 5 volts

5) The other 4 values, aaa,bbb,ccc,ddd cycle through a total of 16
parameters which you need the telemetry equations to figure out.

6) The 8 command switches abcdefgh all show "1"s meaning they are all off.

7) The two control switches labeled "xy" are opposite and show 1's when
activated.  THey are 00 in safe mode and represent the default of both
batteries being cross connected and both transmitters being
crossconnected.  In normal mode, we command them  to isolated, or "11".

8) Lastly all the command switches of both the A side (W3ADO) and the B
side (PCSAT) are paralleled.  If one is set to 0, the other system should
also show it.  The two CTRL switches are similarly paralleled in
"function", but only the side that was acutally commanded will show it in
the telemetry.

The detils of the telemetry equations are all posted on the PCsat web page
below.

Thanks again to EVERYONE for such a long and memorable day!

WB4APR@amsat.org, Bob

ISS-APRS FAQ:       http://www.ew.usna.edu/~bruninga/iss-faq.html
PCsat Design        http://www.ew.usna.edu/~bruninga/pcsat.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


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