[eagle] Re: what is going on?, some technical content at last.

Lyle Johnson kk7p at wavecable.com
Tue Jul 15 20:01:53 PDT 2008

> AO-40 was heavily promoted in QST and downlinks were 10 dB stronger than 
> AO-13 so activity went up.

Yep, sometimes I heard 4 or 5 stations in addition to the Colorado 
continuous SSTV downlink! And LEILA stepping on everything it could find 
(except the SSTV downlink :-(

> I don't know how long it would have lasted. One 
> interesting fact was that the AO-13 70 cm downlink worked much better in Los 
> Angeles than the 2 meter downlink. Ambient noise was about 15 dB lower.

AO-40 had downlinks strong enough to actually use.  AO-13 was definitely 
for weak-signal operation and needed serious antennas.  Karl's analog 
HELAPS was realy pushing the envelope to get near 100 kHz bandwidth.  An 
SDX could do it easier - but we really need to prove the SDX can 
tolerate the radiation and recover from a hit.  A reliable narrowband 
transponder is to be preferred over an unreliable wideband transponder 
:-)  The original Eagle proposal, if memory serves me correctly 9it 
often does not) was to have a linear transponder and the SDX was goign 
to be an experiment on the 2 meter downlink, 50kHz wide or so, with a 
bypass at the IF so if it became unreliable we could still get 
engineering beacon data on that downlink.  A coded S-band downlink is 
probably even better, though, based on AO-40 experience.


Lyle KK7P

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