[amsat-bb] Re: C Band Downconverter

Edward R. Cole al7eb at acsalaska.net
Fri Sep 15 07:54:50 PDT 2006


I have been following your questions with Domenico's answer to you.
Here are my thoughts and "assumptions" (as I do not think it has been
established by Eagle design team at this early time):

1.  For mode S/C I suspect they will come out with a single dish design
(dual S/C feed).  Dual-band mw feeds have been previously designed for
higher mw bands, so this is probably a good assumption.  The single dish
would fit the "apartment size" station objective of Eagle.  It also makes
2.  Eagle Team have already stated that the C-band downlink sub-band at 5
GHz is above the freq that are allocated for wireless data devices
(hopefully will not suffer interference from them).  The old C-C Rider
concept had the uplink side down near the wireless band.  Your 5.8 Ghz
wireless should coexist with Eagle mode-C from what the Eagle Team has
already stated.
3.  Dom makes a good point about choice of IF for the C-band downconvertor.
 70cm makes sense as the IF.  There is no equipment that I know of existing
at this time.  Eagle Team has already stated they will be providing a
mode-S/C ground station design (or kit, or?).  There is no "ready to go"
surplus stuff like the 2.6 GHz MMDS that made mode-S fairly easy for AO-40.
4.  You are asking for information way premature.  Eagle is not at the
point of having the design "in concrete" so it would be wise to wait till
things are further along to begin building your ground station.  Mode- U/V
is pretty easy to guess at.  If mode-S (downlink) were added I would assume
(for now) something close to AO-40 (but maybe S2 level signals or lower?).

Its a guessing game right now.  Until Eagle Team has firmly set the
satellite parameters the path-link cannot be calculated with any certainty
so your ground station requirements are similarly undefined.

I would suggest that getting our home stations ready for P3E would be the
priority.  Then one can hope that Eagle will not be too far different in
requirements on the common modes.

As the above is just my best guess (based on lots of assumptions, not hard
facts).  Caveat Emptor :-)

73's Ed - KL7UW

At 09:47 AM 9/15/2006 -0400, sco at sco-inc.com wrote:
>I have a SSB downconverter for S band. Does anyone know if there are 
>any downconverters for 5830-5850 ghz for downlink via Eagle C band? 
>Looks like i would want a 70cm IF in that?
>Les W4SCO
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Ed - KL7UW  
http://www.qsl.net/al7eb - BP40iq 
144-EME: FT-847, mgf-1801/1402, 4xM2-xpol-20, 170w
432-EME: FT-847, mgf-1402, 1x21-ele (18.6 dBi), 60w

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