[amsat-bb] PSK-31 Sat Xponder?

[Bob Bruninga <bruninga@xxxxxxxx>]

I still think we might fit a PSK-31 XCVR into our satellite within these
constraints.  It can operate in two modes:
 
Mode 1 - 10m SSB UP ==> 2m FM down   
Mode 2 - UHF FM up  ==> 10m SSB down
 
There are many advantages to #1 as noted on this PSK31 SIG, but the BIG
disadvantage is that it competes with our primary mission and so can
only be enabled on a case-by-case basis (And I hate satelites that
change modes!).  But it would be a good test of future dedicated 
transponders of this ilk.
 
Mode 2's main advantage is that we might be able to leave it on all
the time since it XMITs on 10m which is not a conflict.  The disadvantage
is that only dedicated PGates can serve as the FM UPLINKS and so it
serves more as a bulk PSK-31 multiplex delivery system, but doesnt support
live QSO's well except by bundling them from the internet or something.
 
Anyway, we can decide that later.  We just need someone to build it..
(Id love to, but no time).  Here are the bounds:
 
Power available is about 1 Watt (8 volt bus or 16v unreg.)
Size is about 3" by 6" by 1"
Antenna is shared 2m whip, 19" long
10m SSB receiver can have less than 0 dBm audio out 
10m SSB xmtr should take baseband audio in and deliver less than 1W PEP
Delivery in about a month or so...
No promises
 
UNKNOWN is how to diplex the 10m XCVR to the 2m whips without
impacting the 2m operations.  A diplexer is easy for a matched dual
band antenna, but thats not what we have.  Its just a 19" whip.
I assume maybe the inductor used for the diplexer can also serve as 
part of the loading coil to help the match.?
 
I wish I had time to work on this one.  SOunds like fun...
 
de WB4APR@amsat.org, Bob

PCsat Design        http://web.usna.navy.mil/~bruninga/pcsat.html
CUBESAT Designs     http://web.usna.navy.mil/~bruninga/cubesat.html
APRS LIVE pages     http://web.usna.navy.mil/~bruninga/aprs.html
APRS SATELLITES     http://web.usna.navy.mil/~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