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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/2JQIKIHS5G4TRELMVZCSX7IBSI2R4F3K/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "006d01c6d305$0ac333e0$0200a8c0@Tanguray",
    "message_id_hash": "2JQIKIHS5G4TRELMVZCSX7IBSI2R4F3K",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/6QJ6IZF75J3GVEODIJJDD7F5ZYVIZPCJ/?format=api",
    "sender": {
        "address": "rogerkola (a) aol.com",
        "mailman_id": "8323dbe496014835b5bd2be9b5ff6f66",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/8323dbe496014835b5bd2be9b5ff6f66/emails/?format=api"
    },
    "sender_name": "Roger Kolakowski",
    "subject": "[amsat-bb] Re: [Fwd: S-band on Eagle]",
    "date": "2006-09-08T05:10:00Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/6QJ6IZF75J3GVEODIJJDD7F5ZYVIZPCJ/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Jim replied....\n\n>>>We validated interference predictions with measurements\nthat have been taken.  The conclusion is that S-band is marginally\nuseful as a downlink today (unusable in many locations), and by the time\nEagle is launched, and through it's lifetime, will be unusable<<<\n\nRoger (WA1KAT) asks...\n\nIs it possible to provide the locations where your measurements were taken,\nwhat prediction criteria were used, and support your statement that the s\nband downlink \"is marginally useful as a downlink today (unusable in many\nlocations)\"\n\nIt seems that actual users of S Band do not support your research and\nquestion your empirical methods.\n\nCould you also provide us with your experience with S Band satellites and\nyour physical location?\n\nMany thanks!\n\nRoger\nWA1KAT\n\n\n\n\n----- Original Message ----- \nFrom: \"Jim Sanford\" <[email protected]>\nTo: <[email protected]>\nSent: Thursday, September 07, 2006 10:53 PM\nSubject: [amsat-bb] [Fwd: S-band on Eagle]\n\n\n>\n>\n> -------- Original Message --------\n> Subject:    S-band on Eagle\n> Date:   Thu, 07 Sep 2006 21:40:37 -0400\n> From:   Jim Sanford <[email protected]>\n> To:     [email protected]\n>\n>\n>\n> Ladies and gentlemen:\n>\n> I have been reading the comments regarding the Eagle S-band downlink\n> decision.  I herewith respond to some.\n>\n> All along, the Eagle project has put a premium on hard science, rigorous\n> peer review, and dispassionate analysis.\n>\n> All along we knew there might or would be some changes to what we've\n> been planning.\n>\n> With several other issues on the move or decided, we took a few days in\n> late June to hammer out, based on science, the transponder situation.\n> We did multiple, independent link analyses, and all came to the same\n> conclusion.  We validated interference predictions with measurements\n> that have been taken.  The conclusion is that S-band is marginally\n> useful as a downlink today (unusable in many locations), and by the time\n> Eagle is launched, and through it's lifetime, will be unusable.\n>\n> Personally, I do not like this decision.  I have S-band equipment that I\n> was looking forward to using.\n>\n> Personally, I can live with this decision, and defend it to myself, let\n> alone anyone else, because I am convinced that it is technically sound.\n>\n> As one of you commented this evening, AO-40 wasn't exactly a rock\n> crusher on S-band.  It worked, and adequately, at least on CW, but was\n> not great.  As I reflect on my personal AO-40 experiences, I now\n> understand that there are 2 reasons for my disappointment.  Local noise\n> was one, and transponder distortion was another -- the latter will be\n> corrected by SDX.  S-band on AO-40, by necessity not choice, got many of\n> us out of our comfort zones and convinced us that microwaves really\n> aren't that hard.  Let's enter the realm of S up and C down with that\n> same realization.\n>\n> REMEMBER THAT AMSAT IS DEVELOPING THE GROUND STATION ALONG WITH THE\n> SPACE SEGMENT.\n>\n> You will not be left on your own to develop ground equipment.  You will\n> not be asked to mortgage your house; affordability by the masses is a\n> key component of the design for the entire system.\n>\n> Comparison with AO-51 is an \"apples and oranges\" thing.  The path losses\n> are much different.  FM is very unlike CW/SSB or wideband digital\n> modes.  Remember that a goal of the Eagle system is that everything is\n> on all the time.  No more matrix switches, no more schedules.  We need\n> up and downlinks to be useful throughout the entire orbit.\n>\n> Why did we \"regress\" to U/V?  For one reason, many of you asked for it,\n> and some of us worked hard to somehow incorporate that capability in\n> response to member's desires.  The foot in the door was the utility of a\n> V-band beacon in case everything else goes sour.  The forcing function\n> was as follows.  A goal of Eagle has always been some kind of hand-held\n> or jump bag portable ground station capability for entry into the\n> emergency area while the tsunami waters are receeding and the hurricane\n> winds are down to gale force.  Many of us thought we could take\n> advantage of the gain in small antennas to do this on the microwaves.\n> Rigorous link analysis led us to the conclusion that the best place to\n> do this is U/V -- both from a RF/DC power perspective, and from a link\n> standpoint.     This leads to the digital and \"traditiona\"l transponder\n> package for U/V, implemented in SDX.\n>\n> Why not also include a (switchable) S-band downlink in parallel with the\n> V-band?  Remember, no switches.  Also, we run into an antenna space\n> problem.  We've already increased the size of the spacecraft from where\n> we started, and for many reasons, do NOT want to build something as\n> large as AO-40.\n>\n> A couple of you have commented this evening that perusing EaglePedia has\n> not revealed the details of the decisions.  That is because, while Bob\n> McGwier (N4HY) and I have been working on the report of the meeting, it\n> is not public.  We've been working hard on it since June, in and around\n> other AMSAT, ham radio, and life events.  Shortly after I push send on\n> this message, I'll begin my final look at that document prior to public\n> release.\n>\n> Before I go spend time with the spousal unit TONIGHT, I will finish it\n> and publish it.  I will send an announcement on the amsat-bb that it is\n> public.  To read the report, go to the EaglePedia main page, and select\n> project index.  From there, select Team and Meetings, and there will be\n> several options, not all public.  The San Diego meeting minutes will be\n> obvious and public.\n>\n> Several of you have commented, \"If S-band is unusable, why is it flying\n> on P3E?\"  Fair question, but I can't answer for AMSAT-DL.  I DO know\n> that the P3E system design is considerably older and farther along than\n> Eagle.  Eagle design decisions were made based on the best information\n> in June of 2006.\n>\n> Aspects of this discussion have been worthy of /dev/null.  More aspects\n> of this discussion have raised valid points and reasonable questions,\n> deserving of response, which is why I've been composing this note for\n> the last four hours or so.\n>\n> A few have raised the old allegation of the builders doing what they\n> want, without regard to users needs.  This is not true.  While the\n> desire to advance the state of the art (part of amateur radio's\n> justification for existence and allocation of valuable spectrum) leads\n> to enthusiasm and study of potentially useful new techniques, this\n> desire had no impact on our analysis-based decisions.  We started with\n> requirements and services, and explored what would deliver.\n>\n> I thank all of you for your interest and support.  Your Eagle team is\n> working hard to develop a system that will serve our needs, as well as\n> advance the state of the art.  As promised, we are making decisions\n> based on sound, peer-reviewed science, not anybody's opinions or desires.\n>\n> Please read the report, study the spreadsheets, download the excel file\n> and play with it.  If you can, make your own measurements and put those\n> numbers into the spreadsheet.  I think you'll understand how these\n> decisions were reached.\n>\n> After contemplating the report, send me your questions.  I'll either\n> respond or forward to he who can best respond.  Another fundamental\n> tenet of the Eagle project is openness, so you have a right to a\n> response to a rational question.  Please recognize that we're volunteers\n> too, and subject to the realities of day jobs, families, and a real\n> life.  Response may not be instantaneous.\n>\n> Thanks again and very 73,\n>\n> Jim\n>\n> James A. Sanford, PE\n> Eagle Project Manager\n> [email protected]\n>\n>\n>\n> _______________________________________________\n> Sent via [email protected]. Opinions expressed are those of the author.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n>\n\n",
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