[amsat-bb] SUCCESSFUL RAFT Transponder Activation!

[Matt Bennett]

Hi All,

On the 0600 UTC western pass this morning (5/27), the
UCISAT ground station crew successfully activated
RAFT's radar transponder as it approached the Texas
radar fence!  After several days of unsuccessful
attempts, the success of this pass was largely
attributed to NORAD obtaining a fresh set of Keps for
RAFT's degrading orbit just before the pass started.
The epoch of the elset was less than 3 hours, so our
pointing was much more accurate than in previous low
EL passes. 

I threw together a simple website with the audio
recording files and audio spectrum analysis of the
transponder tone from the successful pass. The site
also has tips and tricks for operators who want to
help record the transmission within the footprint: 

http://ucisat.eng.uci.edu/RAFT.php

According to Bob Bruninga (WB4APR), the audio
recording on the website is in fact the transponder
picking up the ground radar signal. However, he
pointed out that we did not catch the narrow beam of
the radar which would have sounded like a bird chirp
in the middle of an open FM carrier. He believes this
could be because RAFT may have been too far west of
the radar station and only catching side lobes, or
because the transponder was activated a bit too early
(difficult to tell due to a last minute configuration
change at our station to accommodate the new elset).

Because of this uncertainty, we absolutely need
additional operators within the eastern and western
pass footprints to help record the transponder audio!!
For the next couple of days, two command stations will
activate the transponder just before the radar fence
penetration on the eastern and western passes around
0400 and 0530 UTC respectively. These times are MUCH
earlier than they were at the beginning of last week
because of the orbit decay (no longer 2-4 AM). Plus,
all you have to do is record the audio! If you're
interested, a procedure for recording stations willing
to volunteer on the website above. For specific info
on RAFT and its mission/operations, please see their
website at
http://www.ew.usna.edu/~bruninga/craft/save-raft.html

Please feel free reply with questions if you're
interested in helping with the recording in the next
few days and one of us will get back to you. Thanks
again to all for your reports and support throughout
this week!

73,

Matt Bennett
KF6RTB 


       
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