[amsat-bb] Re: Why do the amsats get more and more complex?
Rick Hambly (W2GPS)
w2gps at cnssys.com
Tue Sep 19 11:41:40 PDT 2006
I can easily imagine how you may have come to the conclusion by listening to
some people on amsat-bb that satellites are becoming bigger, more complex
and more expensive while not providing you with better services. You might
even think that AMSAT officials are not listening. Nothing could be further
from the truth.
P3E is designed to provide services similar to AO-13 in an effort to make it
smaller, cheaper and simpler than AO-40. It also will carry experiments
essential to the future P5A mission to Mars. This is a very reasonable
increase in complexity for a good purpose.
Eagle is intended to be a series of satellites. Eagle has been designed to
be smaller, lighter and cheaper than AO-40. Its shape was designed to
optimize a low inclination orbit like the one AO-40 attained. This
unintended orbit turned out to be very attractive to many users and it
provides for orbit stability and much less propulsion, further reducing
mission risk. It also carries fewer payloads and these payloads have been
specifically chosen to get the best performance for the maximum number of
Both P3E and Eagle have chosen Software Defined Transponders (SDXs) to
implement the "linear transponder" functions for many reasons. Among these
are efficiency, stability, linearity, cost, in-flight performance
improvement, the ability to simultaneously share the transponder with other
modes (Packet, APRS, SMS are possible examples), and the ability to change
performance parameters in flight. This choice does not make the satellite
bigger, more expensive, or less useful, etc. In fact, it is just the
Eagle will carry a payload that it is hoped will revolutionize Amateur
Satellite communications and Ham Radio as a whole. Initially called C-C
Rider, I will call it the Advanced Communications Package (ACP) because it
no longer uses C-band for both uplink and downlink. This package will be
designed to bring satellites and DX to you and to many other Hams who have
never been able to use a satellite or operate DX before. This is because
the ground station antenna will be small, power levels reasonable, many
modes will be supported (from Voice and CW to Video and data
communications), the ground station will be affordable and the signal
quality will be superior. Much of this is accomplished through the use of
digital techniques so it will require all new equipment on the ground. AMSAT
will design the ground station equipment and publish everything so you can
buy it, copy it, sell it, or build it.
The Eagle band plan has been the subject of much discussion, of late. Eagle
is still in the design phase and the band plan is not finalized, so don't
worry just yet. The confusion was the result of the ACP (C-C Rider) team
realizing that they had to find another band for the uplink. They chose
S-band for some good reasons but that recommendation is under review by the
whole Eagle team and is not yet final. There should be a final announcement
at the AMSAT Symposium in a few weeks. I encourage everyone to come to the
Symposium and meet your AMSAT officials and learn what is really happening
There is much more I could say but, in summary, the new satellites are
getting better in every way compared to the old ones. The future is bright
and we need your support and involvement to achieve these goals.
Subject: [amsat-bb] Why do the amsats get more and more complex?
From: Jason White <jason at xxxxxxxxxxxxxxxx>
Date: Tue, 19 Sep 2006 10:48:44 -0400
This is intended to be an honest question that I've wanted to ask, but I
don't want to spark controversy or long threads that monopolize the
reflector. I have a feeling this could go either way, so I'm just asking
politely that the thread not go that way! It's not my intent.
Anyway, I'm just curious why it seems that every new satellite project
proposed seems to be bigger and more complex than the last? I keep hearing
about exotic modes and uplink/downlink bands for P3E. Software defined
transceivers, etc. etc. and what it looks like to me are more and more
failure points. I understand the need to push the limits of technology as a
justification for our very existence, but personally I feel like the designs
are overly complicated and highly priced. I'm not ready to switch my earth
station to SDRs, for instance.. I'm dubious about putting one into orbit..
then again, I'm not skilled enough to make those sorts of decisions.
What I'm getting at is that Oscar 7 proved how reliable older technology can
be.. For the price of one of the phase 3 birds it seems like several Mode B
linear transponder sats could be put up, or a few more FM sats. I personally
would much rather see a modest mode B sat in AO-40s intended orbital pattern
than to try to wrangle parts for microwave.
Did it get too easy for people or something?
Wouldn't it be better to separate out some of the more experimental stuff
from the old standbys? That way a failure of one whole sat would still leave
something usable for the same money spent. My vote would be to piggyback a
completely independent analog satellite onto P3E "just in case".
Like I said, please, I'm looking for a real, thought out response. I didn't
write the above to be a critique or to troll or anything like that, I am
just curious because it seems to me, as an outside observer, that after the
failure of AO-40 the direction was to go bigger and even more complicated,
which left me cold considering what I had done at my station to work AO-40.
Even when AO-40 was up I felt it was very odd that time and money were spent
on components and systems that were never used (did the solar panels ever
deploy?) Yes, I know the sat was damaged, and that explains a good bit of
it, but it still felt like some things were wasted. Emphasis on "felt".. I
couldn't know the real process that resulted in the decisions made.
If someone could help me understand why the direction is the way it is maybe
I could get excited about the bigger sats, but I think you get more "bang
for the buck" with the smaller less complicated birds. My favorite so far is
PCSat I. Mostly off the shelf hardware and I had a very easy time
digipeating APRS through it. One of those in an elliptical orbit would be a
Jason - N1XBP
P.S. - One last plea, this isn't a troll! I'm worried people will think it
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