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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/QN6636LXAYH7ABLP6UEXV3ZP3XGYVRWQ/?format=api", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api", "message_id": "[email protected]", "message_id_hash": "QN6636LXAYH7ABLP6UEXV3ZP3XGYVRWQ", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/HQNZRN5A5RSKVRORZJ6CIQCRJIGZYIDM/?format=api", "sender": { "address": "zleffke (a) vt.edu", "mailman_id": "57a24afb1cf641f98121841e6753c12e", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/57a24afb1cf641f98121841e6753c12e/emails/?format=api" }, "sender_name": "Zach Leffke", "subject": "Re: [amsat-bb] Community Survey Request -- crosslinks, multi-hop packet, and satellite DX", "date": "2017-04-03T00:16:33Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/QMVGUCGI5DPA4M553DF72EKSGWFLKFYC/?format=api", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "Oh and I should also mention that for #1 there, I'm really really \npushing that 'providing a service to the Amateur Radio Community' be an \nactual project goal. Like, they can't declare mission success unless \nhams are also using the constellation. So 'distance records' per say \naren't a requirement, but if I get my way, 'Providing Amateur Service' \nwill be on the Mission Goals list along with the science goals.\n\n\n-Zach, KJ4QLP\n\nResearch Associate\nAerospace Systems Lab\nTed & Karyn Hume Center for National Security & Technology\nVirginia Polytechnic Institute & State University\nWork Phone: 540-231-4174\nCell Phone: 540-808-6305\n\nOn 4/2/2017 8:13 PM, Zach Leffke wrote:\n> Thanks again for the responses both on and off list, keep 'em coming!\n>\n> 1. No, not really a an academic goal. But cross linking is a \n> requirement. And pseudo-range determination is a requirement. So, \n> 'distance records' or at least multi-hop comms are a natural extension.\n>\n> 2. 3 1Us in a single P-POD. But, different drag profiles and \n> different masses. One has a drag brake that will be deployed shortly \n> after deployment from the PPOD and after initial checkout. The other \n> two have the same profile but different masses.\n>\n> 3. Aiming for an ISS deployment. Overall science goal is to generate \n> data for atmospheric density models at LEO and low LEO altitudes. So \n> higher would be better for the crosslinking/distance, but would be \n> worse for the science. So it will be a relatively short mission, \n> current estimates on the order of 6 months or so.\n>\n> 4. We're still sorting out the exact operating details. Earlier I \n> gave a two satellite example, simplest case. We'll see how \n> complicated we can make it as we move forward. One options is up to \n> one, across to the other two, and down from both. Another is the \n> triple hop (the really desirable one), where each time it hits a new \n> bird, it gets sent on the crosslink and on the downlink. We don't \n> have a specific plan yet, which is part of why I sent out the survey \n> request, to see what people would be interested in, if at all, so we \n> can try to incorporate it into the design.\n>\n> 5. yesss!!! different modes, different options, different ways to \n> reconfigure, either from the ground or with built in 'fallback' \n> operating modes. All the kind of things we're discussing and working \n> through, but are leaving to the students to decide / figure out. I'm \n> only a faculty advisor on the project, so can lob recommendations at \n> my team, but I'm not in charge. We know for a fact (or are at least \n> really really sure) that we will almost certainly lose one of them \n> (the one with the drag brake) faster than the others. So the comms \n> will need to be able to adapt.\n>\n> 6. Thats all the money we could drum up for the mission. But we'll \n> take it, and are grateful for the chance here! I'm just hoping we can \n> balance power budgets appropriately, cause yeah, its tight.\n>\n>\n> -Zach, KJ4QLP\n>\n>\n> Research Associate\n> Aerospace Systems Lab\n> Ted & Karyn Hume Center for National Security & Technology\n> Virginia Polytechnic Institute & State University\n> Work Phone: 540-231-4174\n> Cell Phone: 540-808-6305\n>\n> On 4/2/2017 7:12 PM, Stefan Wagener wrote:\n>> A few quick thoughts:\n>>\n>> 1. Is the \"long distance record\" truly an academic goal? I hope that \n>> this\n>> is just a side effect of a more scientific endeavour :-)\n>> 2. How will the deployment of the satellites being scheduled? Too close\n>> together means long time for separation to make it useful but longer\n>> lifetime for use. Too much initially separation and the satellites won't\n>> see each other for too long.\n>> 3. How about the deployment altitude. The higher the better?\n>> 4. What happens to the sat in the middle, just a link between the other\n>> ones and no direct contact/use?\n>> 5. How can the system be programmed that if one satellites fails it \n>> still\n>> works?\n>> 6. Why 1Us and not bigger for better power budget and redundancies?\n>>\n>> Have fun,\n>>\n>> 73, Stefan VE4NSA\n>>\n>> On Sun, Apr 2, 2017 at 5:54 PM, KO6TZ Bob <[email protected]> \n>> wrote:\n>>\n>>> Zach,\n>>>\n>>> I like what I see so far on your initial proposal.\n>>>\n>>> In the past, I have been involved with 2-HOP and 3-HOP packet attempts\n>>> using various combinations of the ISS, NO-44 and NO-84 when they \n>>> were all\n>>> working on 145.825MHz.\n>>>\n>>> Your proposal of using a 9K6 FSK 2-port_digi's on board three \n>>> satellites\n>>> in the same orbital track resolves what I believe to be the main \n>>> challenges\n>>> we faced in our 1200 baud experiment. If the footprints overlap, the\n>>> satellites should be able to talk to each other.\n>>>\n>>> 1) Since the satellites were in different orbits, there was Doppler \n>>> shift\n>>> in the signal between them. In your proposal, doppler is minimal \n>>> for FM\n>>> packet.\n>>>\n>>> 2) With your 2-port digi, the repeated packets between satellites will\n>>> not be interfered with by multiple up link signals. Improving the \n>>> success\n>>> rate.\n>>>\n>>> 3) I find that 9K6_FSK is as easy to copy as 1200baud, so \n>>> efficiency in\n>>> channel usage is gained.\n>>>\n>>> Once the operators acquire confidence in establishing basic 2 & 3 Hop\n>>> packet contacts, the other experiments and distance records you \n>>> mentioned\n>>> will follow.\n>>>\n>>> I'm in.....\n>>>\n>>> BOB\n>>> KO6TZ\n>>>\n>>> _______________________________________________\n>>> Sent via [email protected]. AMSAT-NA makes this open forum available\n>>> to all interested persons worldwide without requiring membership. \n>>> Opinions\n>>> expressed\n>>> are solely those of the author, and do not reflect the official \n>>> views of\n>>> AMSAT-NA.\n>>> Not an AMSAT-NA member? Join now to support the amateur satellite \n>>> program!\n>>> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb\n>>>\n>> _______________________________________________\n>> Sent via [email protected]. AMSAT-NA makes this open forum available\n>> to all interested persons worldwide without requiring membership. \n>> Opinions expressed\n>> are solely those of the author, and do not reflect the official views \n>> of AMSAT-NA.\n>> Not an AMSAT-NA member? Join now to support the amateur satellite \n>> program!\n>> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb\n>\n> _______________________________________________\n> Sent via [email protected]. AMSAT-NA makes this open forum available\n> to all interested persons worldwide without requiring membership. \n> Opinions expressed\n> are solely those of the author, and do not reflect the official views \n> of AMSAT-NA.\n> Not an AMSAT-NA member? Join now to support the amateur satellite \n> program!\n> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb\n\n", "attachments": [] }