[eagle] Re: what is going on?, some technical content at last.
John B. Stephensen
kd6ozh at comcast.net
Tue Jul 15 21:01:50 PDT 2008
The S band downlink was very useful on AO-13. Mode BS allowed me to copy
weak signals using the S downlink and others to copy me on the V downlink.
By the time of AO-40 I had periodic long duration interference from WiFi
devices in the neighborhood so the S downlink was unusable for hours at a
----- Original Message -----
From: "Lyle Johnson" <kk7p at wavecable.com>
To: "John B. Stephensen" <kd6ozh at comcast.net>
Cc: "Andrew Glasbrenner" <glasbrenner at mindspring.com>; "Bob McGwier"
<rwmcgwier at gmail.com>; "'Bill Ress'" <bill at hsmicrowave.com>; "'David
Goncalves'" <davegoncalves at gmail.com>; "'AMSAT BoD'" <bod at amsat.org>;
<eagle at amsat.org>
Sent: Wednesday, July 16, 2008 03:01 UTC
Subject: Re: [eagle] Re: what is going on?, some technical content at last.
>> 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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