Re: [amsat-bb] Eagle without mode S

[Robert McGwier <rwmcgwier@xxxxxxxxxxx>]

Several things.

We will propose that we be as far away from P3E's S band downlink as 
possible to minimize interference.  This will be done in concert with 
our German partners on P3E.  But please check out the details on the S 
band and V band proposed transmitters and systems on P3E.   The S band 
does appear to be subsidiary to the V band downlink on P3E for all sorts 
of reasons.

We are proposing to have a hugely improved U/V linear transponder over 
our previous proposals.  Much bigger antennas on the spacecraft,  more 
power on the downlink, lessening the requirement for the large 2 meter 
antennas (such as the monster crossed 11 element yagi's) by giving it 
more power and more antenna.   It will fly HELAPS and will have a very 
high dynamic range even at the cost of some on board power.  We are not 
proposing 25 kHz,  we are proposing much wider but the width will be 
determined by calculation.   It will be at least 50 kHz but it can be 
set by SOFTWARE in the SDX.  The SDX can support at least 100 kHz.  We 
need calculate to figure out our link margins but that is completely 
settable ON ORBIT.  I love the SDX!

We are planning for enough solar generator capacity to ALWAYS be turned 
on for both the linear and digital transponders.   This means we must do 
very careful design and testing to make sure one transmitter does not 
interfere with the other transponder, receiver, etc.   We are proposing 
a solar array geometry that will NEVER have bad sun angles or nasty 
seasons.  The minimum power time of year is being designed to support 
ALL MODES AT ALL TIMES.     I insisted that I would not be a party to 
half measures where we had the most important payload operating only on 
experimental Wednesdays so not one person in 100 would make the 
investment and such that the development would fail.   We are 
concentrating our efforts on building two well designed robust systems 
that can operate simultaneously.

People are getting emotional and they don't really  know what it is we 
are proposing.  It is the unfortunate result of the early release of 
only the peripheral details without the rest of the satellite.  The rest 
was to be delivered in the journal and further released at the AMSAT 
annual meeting.   Please give us your forbearance until you at least 
understand what it is in reality we are proposing because we are years 
away from the launch of this spacecraft.  We have to have our crystal 
ball out now to make design decisions that we believe will be valid  
5-15 years from now (assuming a ten year life time on orbit).

73's
Bob
N4HY

-- 
AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
"An expert is a man who has made all the mistakes which can be
made in a very narrow field."  Niels Bohr
----
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