[amsat-bb] Community Survey Request -- crosslinks, multi-hop packet, and satellite DX

[Zach Leffke]

Oh and I should also mention that for #1 there, I'm really really 
pushing that 'providing a service to the Amateur Radio Community' be an 
actual project goal.  Like, they can't declare mission success unless 
hams are also using the constellation.  So 'distance records' per say 
aren't a requirement, but if I get my way, 'Providing Amateur Service' 
will be on the Mission Goals list along with the science goals.


-Zach, KJ4QLP

Research Associate
Aerospace Systems Lab
Ted & Karyn Hume Center for National Security & Technology
Virginia Polytechnic Institute & State University
Work Phone: 540-231-4174
Cell Phone: 540-808-6305

On 4/2/2017 8:13 PM, Zach Leffke wrote:
> Thanks again for the responses both on and off list, keep 'em coming!
>
> 1.  No, not really a an academic goal.  But cross linking is a 
> requirement.  And pseudo-range determination is a requirement. So, 
> 'distance records' or at least multi-hop comms are a natural extension.
>
> 2.  3 1Us in a single P-POD.  But, different drag profiles and 
> different masses.  One has a drag brake that will be deployed shortly 
> after deployment from the PPOD and after initial checkout.  The other 
> two have the same profile but different masses.
>
> 3.  Aiming for an ISS deployment.  Overall science goal is to generate 
> data for atmospheric density models at LEO and low LEO altitudes. So 
> higher would be better for the crosslinking/distance, but would be 
> worse for the science.  So it will be a relatively short mission, 
> current estimates on the order of 6 months or so.
>
> 4.  We're still sorting out the exact operating details. Earlier I 
> gave a two satellite example, simplest case.  We'll see how 
> complicated we can make it as we move forward.  One options is up to 
> one, across to the other two, and down from both.  Another is the 
> triple hop (the really desirable one), where each time it hits a new 
> bird, it gets sent on the crosslink and on the downlink.  We don't 
> have a specific plan yet, which is part of why I sent out the survey 
> request, to see what people would be interested in, if at all, so we 
> can try to incorporate it into the design.
>
> 5.  yesss!!! different modes, different options, different ways to 
> reconfigure, either from the ground or with built in 'fallback' 
> operating modes.  All the kind of things we're discussing and working 
> through, but are leaving to the students to decide / figure out.  I'm 
> only a faculty advisor on the project, so can lob recommendations at 
> my team, but I'm not in charge.  We know for a fact (or are at least 
> really really sure) that we will almost certainly lose one of them 
> (the one with the drag brake) faster than the others.  So the comms 
> will need to be able to adapt.
>
> 6.  Thats all the money we could drum up for the mission.  But we'll 
> take it, and are grateful for the chance here!  I'm just hoping we can 
> balance power budgets appropriately, cause yeah, its tight.
>
>
> -Zach, KJ4QLP
>
>
> Research Associate
> Aerospace Systems Lab
> Ted & Karyn Hume Center for National Security & Technology
> Virginia Polytechnic Institute & State University
> Work Phone: 540-231-4174
> Cell Phone: 540-808-6305
>
> On 4/2/2017 7:12 PM, Stefan Wagener wrote:
>> A few quick thoughts:
>>
>> 1. Is the "long distance record" truly an academic goal? I hope that 
>> this
>> is just a side effect of a more scientific endeavour :-)
>> 2. How will the deployment of the satellites being scheduled? Too close
>> together means long time for separation to make it useful but longer
>> lifetime for use. Too much initially separation and the satellites won't
>> see each other for too long.
>> 3. How about the deployment altitude. The higher the better?
>> 4. What happens to the sat in the middle, just a link between the other
>> ones and no direct contact/use?
>> 5. How can the system be programmed that if one satellites fails it 
>> still
>> works?
>> 6. Why 1Us and not bigger for better power budget and redundancies?
>>
>> Have fun,
>>
>> 73, Stefan VE4NSA
>>
>> On Sun, Apr 2, 2017 at 5:54 PM, KO6TZ Bob <my.callsign at verizon.net> 
>> wrote:
>>
>>> Zach,
>>>
>>> I like what I see so far on your initial proposal.
>>>
>>> In the past, I have been involved with 2-HOP and 3-HOP packet attempts
>>> using various combinations of the ISS, NO-44 and NO-84 when they 
>>> were all
>>> working on 145.825MHz.
>>>
>>> Your proposal of using a 9K6 FSK 2-port_digi's on board three 
>>> satellites
>>> in the same orbital track resolves what I believe to be the main 
>>> challenges
>>> we faced in our 1200 baud experiment.  If the footprints overlap, the
>>> satellites should be able to talk to each other.
>>>
>>> 1)  Since the satellites were in different orbits, there was Doppler 
>>> shift
>>> in the signal between them.  In your proposal, doppler is minimal 
>>> for FM
>>> packet.
>>>
>>> 2)  With your 2-port digi, the repeated packets between satellites will
>>> not be interfered with by multiple up link signals. Improving the 
>>> success
>>> rate.
>>>
>>> 3)  I find that 9K6_FSK is as easy to copy as 1200baud, so 
>>> efficiency in
>>> channel usage is gained.
>>>
>>> Once the operators acquire confidence in establishing basic 2 & 3 Hop
>>> packet contacts, the other experiments and distance records you 
>>> mentioned
>>> will follow.
>>>
>>> I'm in.....
>>>
>>> BOB
>>> KO6TZ
>>>
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>> _______________________________________________
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>
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. 
> Opinions expressed
> are solely those of the author, and do not reflect the official views 
> of AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite 
> program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb