<div dir="auto">I'm always worried about seamless handover when one detects the lack of agreement and you swap to the other. <div dir="auto"><br></div><div dir="auto">So I want to say I strongly recommend that state be maintained in ECC memory and when fault is found the "other" processor pair is selected, "boots", and takes over after initializing and restoring saved state.</div><div dir="auto"><br></div><div dir="auto">This is allows handoff to be asynchronous rather than trying to maintain perfect synchrony.</div><div dir="auto"><br></div><div dir="auto">If there are unsafe activities possible then the highest priority is shutting those down in some priority order: propulsion, attitude change, .......</div><div dir="auto"><br></div><div dir="auto">I can relate the tale that the strongest delivered proclamation I ever received from Karl Meinzer was to never attempt this at all. He was adamantly opposed to multiple processors and handoffs in spacecraft.</div><div dir="auto"><br></div><div dir="auto">73s</div><div dir="auto">Bob</div><div dir="auto">N4HY </div></div><br><div class="gmail_quote"><div dir="ltr">On Mon, May 28, 2018, 10:15 AM Jonathan Brandenburg via Ground-Station <ground-station@lists.openresearch.institute> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<p>[I'm speaking a bit for Zach Metzinger, so I've copied him on
this email. I'm not sure if he's on this mailing list or not and
want him to be in a position to expand or correct my statements,
or even disavow anything I'm saying, if he desires.]</p>
<p>A small team, primarily Zach Metzinger with the assistance of
others (Bill Reed, Jordan Trewitt, me), is designing an IHU based
on the TI Hercules safety-critical processor. While the Hercules
is not necessarily radiation-hardened, the processor is designed
for operation in very noisy environments. It's also designed to
detect faults, by executing instructions on two cores in lockstep,
detect when the result differs, and signal a failure. (I imagine
there are other features, but this is a high point.)<br>
</p>
<p>So, we've been designing an IHU with two Hercules processors and
two digital transceivers configured in a fail-over configuration
along with redundant power circuits. There's still work to be
done, but Zach has begun laying out this board in a 1U footprint.</p>
<p>[This is the part where I'm speaking for Zach...] I believe Zach
is committed to ensuring this design is open and available. As a
result, I expect we'll be quickly publishing this work (by
ITAR/EAR definitions) as we achieve milestones. This IHU work was
begun before the AMSAT Golf program was kicked off and is now
being integrated into Golf. I don't know of any reason this work
couldn't be leveraged and used in other satellites.<br>
</p>
<p>Thus, I submit this IHU-in-progress for our consideration...</p>
<p>Jonathan Brandenburg<br>
</p>
<br>
<div class="m_1195508381222618656moz-cite-prefix">On 5/16/2018 1:54 PM, Bruce Perens via
Ground-Station wrote:<br>
</div>
<blockquote type="cite">
<div class="gmail_quote">
<div dir="ltr"><br>
</div>
<div class="m_1195508381222618656gmail_forwarded">Legal stuff first: Image credit:
XKCD #1992: "SafetySat" at <a href="http://xkcd.com/1992/" target="_blank" rel="noreferrer">http://xkcd.com/1992/</a>
Creative Commons Attr-NC 2.5 license.
<div>
<div dir="auto"><br>
</div>
<div dir="auto">Yes, we should have a satellite program and
do what AMSAT is not. Everyone I have heard from so far is
asking for a "DX Satellite", "like AO-13" and not LEO.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Mission should include digital
communications using Michelle's design. I also have some
blue-sky ideas that we can discuss at Hamvention, some of
them might be good grant candidates. Think grant. Money is
out there, we will start soliciting as soon as we have a
mission plan.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Build the satellite (and maybe P-pods)
first, approach launch providers with flight hardware in
hand and ready to go. Satellites are cheap, launches are
not. Be prepared to take advantage of opportunities on
very short schedules.</div>
<div dir="auto"><br>
</div>
<div dir="auto">I think we should fabricate extras of parts
we design, and sell them as TAPR does to supplement their
budget, but right off of Amazon Prime. Make them really
easy and fast to buy, and someone else does the shipping.
Aim at flight-quality but mostly going to classroom use
rather than flight, to start. Nicer for the class than the
PLA 3-D printer stuff that is so obviously non-flight that
they are using now.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Aim for 100% to 200% markup over cost,
Amazon gets around 18% of the order and a warehouse fee
and fulfills from their warehouse. Most of the commercial
cubesat companies, like Pumpkin, are running 500% to 1000%
markup in order to amortize R&D and operational costs
and still make a profit, but most of them have flight
heritage that we would not start out with. We use slave
labor :-) and can mostly base our final cost on
fabrication and sales costs.</div>
<div dir="auto"><br>
</div>
<div dir="auto">I have been looking at cubesat structures
(because I feel competent enough to make one, at least
with your help) and I really like Pumpkin's design. Almost
all laser-cut 5000-class sheet aluminum, bent on a brake,
anodized corners on the sheet, only the 8 corner pieces
are machined, and that only simple shaping and drilling of
bar stock into a simple rectilinear shape with
specified-radius corners and edges and a place to put the
springs and cutoff switch pins. Most other designers
seemed to be more interested in showing their skill in CNC
machining than making a practical structure. If you look
at Pumpkin's stuff, it is clear that they put a lot of
thought into mechanical engineering. And they actually
engineered for cost and mass-production, while few others
bothered. We will not ever directly copy anything (I am an
intellectual property specialist, and will keep us legal),
but we can and should learn from their work.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Besides the structure, other
non-mission-specific stuff we should be building would
include an IHU (computer) and the other general bus
components: lithium battery pack with heaters and per-cell
management, magnetorquer, solar panels (what cells, from
where?), maybe some heat distribution components like
adiabatic heat pipes?</div>
<div dir="auto"><br>
</div>
<div dir="auto">Can we hear from volunteers for any of this?</div>
<div dir="auto"><br>
</div>
<div dir="auto">LIME mini might be a good flight candidate,
besides Ettus and Rincon. Their CEO and Open Source guy
are very friendly and their PCB design may already be
licensed appropriately. No idea how the chip would take
radiation.</div>
<div dir="auto"><br>
</div>
<div dir="auto">We should look into the Open Source finite
element analysis and CFD programs. We should simulate as
much as possible before going to thermal vacuum, vibration
and shock, etc. And publish all input data so that it can
be reused along with our part designs.</div>
<div dir="auto"><br>
</div>
<div dir="auto">I saw a really nice indium electronic
thruster at Cal Poly. All proprietary, of course. Goes up
with the fuel solid, gets heated in flight. No moving
parts, works by wicking through a sintered tip. Probably
very patented. But a source of ideas.</div>
<div dir="auto"><br>
</div>
<div dir="auto"> Thanks</div>
<div dir="auto"><br>
</div>
<div dir="auto"> Bruce</div>
<div dir="auto"><br>
</div>
<div dir="auto"><br>
<div class="gmail_quote">
<div dir="ltr">On Wed, May 16, 2018, 09:23 Michelle
Thompson <<a href="mailto:mountain.michelle@gmail.com" target="_blank" rel="noreferrer">mountain.michelle@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Heh! The SDR really ties it all
together in your sketch there. <br>
<br>
Yes, there's interest in building an open source
satellite. The time is right and we have the best
chance of making it happen that I've seen in a long
time. There's a variety of forces at work in the
industry, in academia, and in open source culture
and achievement that help make a modern, innovative,
amateur, open source payload possible. <br>
<br>
I don't know enough about MEO but I'm game for
supporting any payload that enables an enduring
amateur community through reliable communications in
space. I'm very happy we get the chance to dig into
this and I want to enable and support it as much as
possible. <br>
<br>
The Careful COTS of an Ettus USRP effort is one way
to get a capable SDR for space. This is a joint
project between Phase 4 Space and GOLF to get the
E310 in play soon/now for GOLF and the E320 later
for Phase 4 Space. Business unit at Ettus is
reviewing it. Systems engineering lead for GOLF
endorsed it as an open source effort. Meeting
minutes were posted to the list. Next steps depend
on what IP from Ettus. We'll proceed with the E320
as far as it takes us regardless. I expect to make a
lot more progress here in late summer/early fall,
especially at GNU Radio Conference 2018.<br>
<br>
The Rincon AstroSDR is another option, and Rincon
has reached out with questions and clarifications in
response to the Kittens Weekly Report. There will be
more talks after Hamvention. Rincon will be a
significant presence at GNU Radio Conference 2018. <br>
<br>
Propulsion, attitude control, solar power, and a
variety of antennas all have open source
flight-tested options at LEO. I don't know much
about navigation. <br>
<br>
I do know that we have a lot of support out there
from like-minded organizations and projects. <br>
<br>
I do know that a payload design is within the
capabilities of people on this list and within our
extended Slack/GitHub/phone/email/club/conference
network. That does not mean it's easy by any
stretch, and it means that our economic development
team will be tested. I think we are up to the
challenge.<br>
<br>
What's the first thing that you think we need to
do? <br>
<br>
<div class="gmail_extra">
<div>
<div class="m_1195508381222618656m_3580039870414392912m_1557477715270845954gmail_signature" data-smartmail="gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div dir="ltr">-Michelle W5NYV<br>
<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
<br>
---------- Forwarded message ----------<br>
From: Howie DeFelice <<a href="mailto:howied231@hotmail.com" target="_blank" rel="noreferrer">howied231@hotmail.com</a>><br>
To: <a class="m_1195508381222618656moz-txt-link-rfc2396E" href="mailto:ground-station@lists.openresearch.institute" target="_blank" rel="noreferrer">"ground-station@lists.openresearch.institute"</a>
<a class="m_1195508381222618656moz-txt-link-rfc2396E" href="mailto:ground-station@lists.openresearch.institute" target="_blank" rel="noreferrer"><ground-station@lists.openresearch.institute></a><br>
Cc: <br>
Bcc: <br>
Date: Wed, 16 May 2018 04:16:15 +0000<br>
Subject: Satellite Building<br>
<div dir="ltr">
<div>
Just wondering if there is interest in
putting together a project to build a
satellite. There is no particular launch
in mind and no particular mission at this
pint other than the generic Amateur Radio
goal of furthering the art of
communication. I think most will agree
that the LAST thing we need another LEO.
To simply exploit the microwave bands I
think we want to consider orbits that
allow hours of coverage at a time. A GEO
would be great, a HEO would be really
good. An overlooked orbit, at least in ham
radio, is MEO. An orbit between 8000 and
10,000 Km would provide about 2 hours of
coverage and orbit the earth about twice a
day. The problem is that not too many
people fly there so we need another
strategy. If we aren't in a big hurry,
maybe we can get there from LEO. This
means we need propulsion, attitude
control, navigation, lots of solar power
and a really cool radio. Does this sound
reasonable? How long would this actually
take with a milli-Newton thruster ? I have
attached a sketch of my first ideas.</div>
<div>
<br>
</div>
<div>
- Howie AB2S </div>
</div>
<br>
<br>
---------- Forwarded message ----------<br>
From: <a class="m_1195508381222618656moz-txt-link-abbreviated" href="mailto:ground-station-request@lists.openresearch.institute" target="_blank" rel="noreferrer">ground-station-request@lists.openresearch.institute</a><br>
To: <br>
Cc: <br>
Bcc: <br>
Date: Wed, 16 May 2018 00:16:18 -0400<br>
Subject: confirm
db1d86455ef4eb7857a41676b75024137549ff1d<br>
If you reply to this message, keeping the
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</blockquote>
</div>
<br>
</div>
</div>
</blockquote>
</div>
</div>
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<br>
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<pre class="m_1195508381222618656moz-signature" cols="72">--
Jonathan Brandenburg
1-214-213-1066
<a class="m_1195508381222618656moz-txt-link-abbreviated" href="mailto:jonathan@jonathanbrandenburg.com" target="_blank" rel="noreferrer">jonathan@jonathanbrandenburg.com</a>
-----------------------
When possible, please sign and encrypt your communication. See <a class="m_1195508381222618656moz-txt-link-freetext" href="https://ssd.eff.org" target="_blank" rel="noreferrer">https://ssd.eff.org</a>
I updated my PGP certificate on December 8, 2015. Please update your keychain:
PGP certificate fingerprint: 824E 8871 5474 61F7 09D4 9B67 8AFC 1E70 924D B20</pre>
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