[amsat-bb] San Diego Microwave Group - Let's talk about microwave digital broadband on ISS

[Michelle Thompson]

Thank you to everyone attending San Diego Microwave Group's 29 June 2020
Zoom meetup. Part of the discussion was about the possibility of the AREx
broadband digital microwave design being potentially deployed on the
International Space Station.

Since we've focused heavily on high earth orbit, geostationary orbit, and
the lunar opportunity with Gateway, the challenges of low earth orbit (ISS)
now need to be addressed. This will be an ongoing process. Here's what
participants recommended at SDMG:

Since there are LEO constellations up to and including Ka band, the
tracking and doppler have been done. It's just a question of learning the
requirements, design patterns, limitations, and techniques.

We already incorporate the near-space communications recommendations from
CCSDS, so we're in good shape there.

HamTV on ISS is at 2.4 GHz, which while lower than our 5/10 GHz, has all
the other aspects of broadband digital. There is plenty to be learned from
there, and meetings are being set up to begin to collaborate with the
principals of HamTV on deeply appreciated advice & next steps.

Strong advice to eliminate antenna pointing. Use an antenna system in space
and on the ground that does not require tracking, and that would
dramatically increase adoption.

With Adaptive Coding and Modulation, all sorts of systems can be
accommodated.

Meaning, a ground station that does track can use a directional antenna
with a lot more gain, and get a much higher bitrate, while a station with a
120 degree field of view would get a lower bitrate, but would not have to
track at LEO. This needs thorough link budgeting.

We have several link budgets in Jupyter Notebook in progress at
https://github.com/phase4space/payload-dmt

If you are interested in helping here, welcome aboard.

Testing for human rated spacecraft incurs a substantial increase in
engineering, paperwork, and time requirements.

Putting the equipment outside instead of inside does not eliminate the
testing requirements. This is going to require advice/direction from ARISS.

Space heritage of this type, where we are an external payload only
requiring power, makes hosted payload options easier to negotiate. There
are 5-6 GEO missions going up in the next 3 years that we could and should
target.

Doppler is a factor here, and we received strong recommendations about
talking with particular ARISS team members with experience. We will be
learning from and incorporating their advice in the very near future.

Thank you all for supporting this project and being generous with your
time, talent, and treasure. We are making excellent progress while
providing all of our work to the general public, with AMSAT as a primary
beneficiary, at no cost.

Next meeting scheduled is an AREx technical team followup (from last
Thursdays ARISS International review) on Thursday 2 July 2020.

-Michelle W5NYV
(One of your AMSAT Directors)



On Fri, Jun 26, 2020 at 11:46 AM Michelle Thompson <
mountain.michelle at gmail.com> wrote:

> Here's an invite to the San Diego Microwave Group zoom meeting to be held
> this upcoming Monday evening (US Pacific 7pm).
>
> I will talk about putting ORI work (payload) on ISS at the meeting to get
> advice and feedback. This affects ground stations and testing for the
> payload equipment. This work directly benefits all AMSAT organizations.
>
> Being on the ISS was raised as a possibility this past week from the
> ARISS/AREx hardware summit meetings.
>
> The San Diego Microwave Group meeting is a regular technical roundtable on
> amateur microwave activities, questions, operations, and experiments. You
> don't have to make a presentation to be part of the call.
>
> If you want to be on the SDMG email reflector, send me an email at
> w5nyv at arrl.net and I will make sure it happens.
>
> Please forward to anyone you think would be interested.
>
> -Michelle W5NYV
>
> Topic: San Diego Microwave Group
> Time: Jun 29, 2020 07:00 PM Pacific Time (US and Canada)
>
> Join Zoom Meeting
> https://us02web.zoom.us/j/81927112936?pwd=UzROZ3MrQnFnTTdFVHgrNjlqaTZ1dz09
>
> Meeting ID: 819 2711 2936
> Password: 487697
> One tap mobile
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>
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> Meeting ID: 819 2711 2936
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> -Michelle W5NYV
>
> "Potestatem obscuri lateris nescis."
>
>