[amsat-bb] Re: FOX-2 Information (was: "Flying repeater" inquiry)

Bryce Salmi bstguitarist at gmail.com
Fri Feb 14 16:00:21 PST 2014

To expand upon the flying repeater email.

"I'd be interested to know if there is going to be any technical challenge
to working Fox 2 or if it will just be yet another ones of Clint's

Now, the actual important comment in this sentence is the reference that
Fox-1 being an FM bird is assumed to be easy to build. Strictly and
professionally speaking this is a huge understatement of the technical
challenges of any satellite. I'll assume you do not work in the the
aerospace industry or have volunteering to build one of the AMSAT
satellites (more than welcome to give it a shot!). Even an easysat is
incredibly hard to build. Beyond the actual transmission mode the satellite
must maintain a healthy power budget, provide telemetry to monitor the
status of the satellite, be implemented in a 95mmx95mmx95mm space (inside
the cube), survive the 5 year mission's expected 30krad dose of radiation,
and survive 16 sunrises/sunsets per day in the vacuum of space (have heat?
can't use convection to get rid it!). Just to name a few items...

To put the sunrise/sunset into perspective (think of the road and other
objects you see cracking due to expansion and contraction) MIL-STD-1540
which is a good idea to follow and the associated specifications usually
require a spacecraft to be designed to survive -34C to +71C temperature
extremes. Try operating a consumer product in that environment and it will
fail pretty quickly.

Also, from an extremely high-level point of view, the only difference
between Fox-1 and Fox-2 will be the FM repeater being changed to the
Software Defined Transponder (SDX). The SDX is a bit more power hungry so
it requires an upgraded Maximum Power Point Tracker and more solar cells to
produce the needed power. Otherwise, Fox-2 and Fox-1 will share a lot of
the same technology. This is good because we don't want to re-invent the
wheel. Therefore I respectively reject the idea that just because Fox-1 is
an FM bird it is not technically challenging to design and build.


On Fri, Feb 14, 2014 at 3:44 PM, Bryce Salmi <bstguitarist at gmail.com> wrote:

> You can already find out more about the prototype maximum power point
> tracker that will be used to power the software defined transponder on
> Fox-2!
> http://edge.rit.edu/edge/P13271/public/Home
> Bryce
> On Fri, Feb 14, 2014 at 2:25 PM, Clayton Coleman <kayakfishtx at gmail.com>wrote:
>> Hi Michael
>> You're in luck.  The Phase 2 Fox series are based on the SDX transponder
>> as
>> tested on ARISSat-1 and not your favorite "flying repeaters."
>> Learn more by visiting the "Meet the Fox Project" page at:
>> http://ww2.amsat.org/?page_id=1113
>> Welcome aboard.  You can join AMSAT and renew via the web store or by
>> calling the office.
>> See http://store.amsat.org/catalog/ and click on "Membership" for several
>> options.
>> 73
>> Clayton
>> W5PFG
>> On Feb 14, 2014 4:04 PM, "Michael" <Mat_62 at charter.net> wrote:
>> > If Fox 2 is a linear bird, I'll even put my money where my mouth is and
>> > renew my long dormant  membership in AMSAT because I will feel that they
>> > are moving in a direction that I and many others have interest in. If
>> it's
>> > just another flying repeater though well..... YAWN....I'm getting sleepy
>> > now.
>> > 73,
>> > Michael, W4HIJ
>> >
>> >
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