PCSAT1 and PCSAT2 two-hop operations
Bob Bruninga, WB4APR, writing on behalf of the US Naval Academy
Satellite Laboratory, reported this week that the original PCSat
(PCSAT1), which is operational only when its solar cells are in
sunlight, has had as many as 45 users in a single day and 72 different
callsigns over a period of two days. This is because PCSAT1's orbit
has taken the satellite into a 12 day full-sun period.
Additionally, PCSAT2, mounted aboard an external strut on the International
Space Station will be activated as its solar cells will be once
again facing the sun as the ISS makes orbital attitude adjustments.
The PCSAT2 user digipeater with its 145.825 uplink and 435.275 downlink
will be back on-the-air.
With PCSAT1 and PCSAT2 both active, the control team at the US
Naval Academy will make a few changes to improve the chances of
mulitple satellite hops of digipeated signals:
1) We will add SGATE as an alias to PCSAT2 so that ANY over the
horizon PCSAT1 originated packets that are heard by PCSAT2 will
be relayed since these packets already contain the SGATE digipeating
path.
2) Stations sending up through PCSAT1 as a first hop may get a
second hop through PCSAT2 if they use any dual hop path (ARISS,
ARISS; or WIDE2-2; or PCSAT2,PCSAT1; etc) The second hop will only
be heard on the PCSAT2 435.275 downlink.
3) As of December 3, the PCSAT2 435.275 downlink was switched down
to 145.825 so that PCSAT2 and PCSAT1 are identical systems both
with uplinks and downlinks on 145.825 acting as a 2-hop constellation
both on 145.825. Both will be supporting the normal APRS aliases
of WIDE, or ARISS, or APRSAT or WIDE2-2 so that you can digipeat
through either one or both.
4) The PCSAT2 dowlink will shift back to 435.275 on 7 Dec to avoid
any possible interference with the next school contact with Sanderson,
TX, on 8 Dec at 1730z.
Bob reminds PCSat users, "Of course, the MORE that try the
FEWER will be the success rate. So if you really don't know what
you are doing, PLEASE do not transmit and just watch. YOUR station
may be the one that SEES the dual hop, so that should be a good
reward too. Make your packet as SHORT as possible and use the shortest
TXD for your TNC. The PCSATs should respond with TXD's as low as
10 which is 100 milliseconds in real-time. Also, transmit occassionally,
NOT repeatedly, maybe once a minute or so.
Bob summarized, "When PCSAT1 returns to eclipses, we are usually
lucky enough to keep her from resetting for a few more weeks and
at least daylight operations can continue normally. But once it
resets, either due to peak user load or a Single Event Upset from
radiation, then we lose her again until the next full sun period
in the first week of March 2006."
For additional details please see the PCSAT2 web page at:
http://www.ew.usna.edu/~bruninga/pcsat2.html
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