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GET /hyperkitty/api/list/[email protected]/email/LJUYVGM6AJLZX54RVK4RUEA345JNZTTH/?format=api
{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/LJUYVGM6AJLZX54RVK4RUEA345JNZTTH/?format=api", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api", "message_id": "[email protected]", "message_id_hash": "LJUYVGM6AJLZX54RVK4RUEA345JNZTTH", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/FEBDCQJ3PAKZ6UFGO4JPZNHRAZYXDDMR/?format=api", "sender": { "address": "bill (a) hsmicrowave.com", "mailman_id": "d7ecbf0c1df148f289f27dd7a8c37974", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/d7ecbf0c1df148f289f27dd7a8c37974/emails/?format=api" }, "sender_name": "Bill Ress", "subject": "[amsat-bb] 2.4 GHz Comments and Proposals", "date": "2006-09-09T03:52:34Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/PSK35MZOI4YT25LHOB26JAFTY63PCHXH/?format=api", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "Hi Bob,\n\nYour response alluded to a desire by many to \"duplicate P3E.\" I didn't read\nthat into the responses. I seriously don't think that's a real issue for\ndiscussion.\n\nFirst the \"sunshine\" comments.\n\nI \"seriously\" appreciate the efforts that you and your team have put in, to\nget us this far in the Eagle development and look forward to a satellite\nthat will have capabilities for many communicators.\n\nSecondly, now lets focus on the \"not so sunshiny\" issue being discussed - a\n2.4 GHz downlink.\n\nI am involved with UWB (Ultra Wide Band) design and deployment. I won't go\ninto UWB details (except to say it will operate somewhere above 3 to 4 GHz\nwith a very, very wide instantaneous bandwidth) but my marketing guys say it\nwill offer the wireless systems of the near future. They may be wrong but I\nthink they're on to something. Why? Simple facts bear them out.\n\nLets just take the cordless phone history. We once had 49 MHz cordless\nphones. They're now gone. Same with 900 MHz phones. Currently 2.4 Ghz is the\ncordless phone \"de jur.\" But what's right around the corner?\n\nFact (1): You could just look at the new 5.8 GHz product offerings by\nHittite, Sirenza, Freescale and whole lot more to see where they're placing\ntheir design emphasis but today was shopping day so I thought I'd do some\nsimple consumer research, if you will.\n\nMy results:\n\nSam Club offered 5 cordless phones - all the 5.8 Ghz variety (i.e. - no 2.4\nGHz phones)\n\nCostco offered 5 cordless phones - 4 were the 5.8 GHz variety and 1 was at\n2.4 GHz.\n\nBest Buy - 3 were 5.8 GHz, 2 were 2.4 GHz.\n\nThe point: Our electronics industry is bent on creating obsolete throw away\nproducts to fuel the economic engines (Being in the industry I can\nappreciate that). Already the move is on for the WiFi applications at 5.8\nGHz (including the high power - 1 watt - 5.8 Ghz applications).\n\nSo in 3 years when Eagel is launched I believe it is very possible that the\n2.4 GHz interference issue may have gotten better with the clearly\npredictable consumer industry transitions up the microwave spectrum and at\nthat time maybe we should be concerned with the vulnerability of the\nproposed 5.8 GHz satellite links???? I believe this argument might be as\nvalid and your groups arguments.\n\nI would also ask - if the inference problem at 2.4 GHz is as severe as you\nrepeatedly state - how come the cordless phones and WiFi systems don't drown\nthemselves out an collapse with their own sea of mutual interference?\n\nWhat I have been reading is a preponderance of AO-40 2.4 GHz operators who\nhave experienced some interference but it didn't destroy their use of the\ncapability. So what's so new about amateurs working with some QRM.\n\nSo instead of just bitching I'm offering some alternatives that could \"sooth\nthe masses!\"\n\nProposal): Put in place a parallel \"2.4 GHz team\" to design and build a 2.4\nGHz downlink capability in the off chance your dire predictions could be\nwrong and room and current can be budgeted for it. Sure - problems will\nabound but its a proactive activity that is worth considering.\n\nProposal (2): As has been suggested here, lets put as much energy in getting\nour satellite allocations modified as we have used to argue 2.4 GHz. While\nit might be too late, WRC-2007 is around the corner and perhaps we can still\nlobby the FCC's Informal Working Group 4 to help us out.\n\nI would offer my help with Proposal (1) and I'm sure there are really\nqualified members would could pursue Proposal (2)\n\nRespectfully (and I mean that)\n\nBill - N6GHz\nAMSAT #21049\n\n\n\n\n\n\n\n\n-----Original Message-----\nFrom: [email protected] [mailto:[email protected]]On\nBehalf Of Robert McGwier\nSent: Friday, September 08, 2006 3:19 AM\nTo: Dave Guimont\nCc: [email protected]\nSubject: [amsat-bb] Re: S band downlink on P3E\n\n\nDave Guimont wrote:\n>\n>\n>\n>\n> 73, Dave [email protected]\n> Disagree: I learn....\n>\n> Pulling for P3E...\n>\n\nAs are many of us. That said, The S transmitter is not the primary\nmode of P3E. The S band transmitter on P3E will be hooked to a dish.\nThis dish will have a half power beam width which will limit the\nusefulness of the S band transmitter to those times of nadir pointing.\n\nThe revelation of the results of our meeting, weeks before we could be\nready to explain carefully that we are taking a system approach to the\ndesign of Eagle, is unfortunate. Not because the conclusions are made\npublic but because there is no context for the decision making process.\n\nWe cannot build an AO-40 class spacecraft. We do not have the\npersonnel, the facilities, and we likely do not have sufficient talent\nthat we can devote to such an enterprise. We have talent in this\norganization and around the world. But all of that talent leads a life\noutside of AMSAT. As an engineering manager for AMSAT it is my\nresponsibility to make cold hard decisions based on personnel,\ncalculation, advice, studies, equipment availability, the\navailability of launches that we can use and on and on.\n\nThe organization overreacted to AO-40. It downsized Eagle\nconsiderably. It set a goal of no motor. It said \"let's do digital\"\nand \"give them a whip antenna on two meters\". It did not say this in a\ncrass manner but those were absolutely the conclusions of the\norganization policies when captured into engineering possibilities.\nIt has literally taken me 11 months to ALMOST right the ship. If the\nother people in the room will admit to it, I single handedly saved the\nlinear transponders in our current designs by\n\na) picking the receiver designer\nb) picking the transmitter designer\nc) choosing SDX as the overall concept for the linear transponder\n\nEVERYONE is on board. But do you think such things are done overnight?\nNO. They are done with leadership and not by whining. These decisions\nand their outcome led to a MUCH improved antenna system, power\namplifier, and absolutely cutting edge efficiencies achievable for this\ntransponder in our current plans. It went from 25 kHz fed to a quarter\nwave monopole on the back side of the spacecraft to serious antenna\nabsolute eating valuable territory on the business side of the\nspacecraft and with bandwidth UP TO (but not necessarily) 100 kHz wide.\nThe bandwidth will be determined by the TYPE of customers we wish to\nserve. We do not want to serve only those who can transmit 10 kW\nEIRP. We do want to support 1 KW EIRP SSB contacts. We also want to\nsupport a text messaging service that will require a shortened dipole on\n70cm and 2m which will not be limited to APRS users.\n\nThe goals stated by the AMSAT board of directors for its next HEO\nspacecraft design as a follow on to P3E (besides supporting P3E in the\ninterim) included aiding those people who live in CC&R (covenant\nrestricted) communities. It included aiding the first responders by\ngiving them the ability to take a back pack full of equipment, set it\nup, and operate quickly. It stated that it wanted to produce a system\nof such satellites over a decade to be available 7/24.\n\nWe have a concept, not a design, for a spacecraft. This concept is an\n\"upsizing\" of the near cubical Eagle. We are filling in the blanks on\nthe concept in an attempt to present a design.\n\nThe concepts we are building to include the ability to use the\ntransponders on this spacecraft 365 days a year, in EVERY year the\nspacecraft is functional and to try and build a spacecraft that will be\nthere and still usable when the third in the constellation is launched.\nDo you think this is easy? Of course not. It is easy to pitch mud when\nyou are not responsible for an outcome.\n\nWe are attempting to have NO bad seasons. We are attempting to have NO\nfunny orbital problems. We are attempting to have the gain antennas\nsolidly usable over 70% of the entire orbit. For these reasons and\nbecause of the desire to serve the CC&R customers, this meant we had to\nuse microwaves to get sufficient gain on the antennas on the spacecraft\nand the ground. We fully understand that Dick Jansson, Drew, Dave,\nTony, and others can give us anecdotes of how they can throw enough gain\non their antenna system and make S band work for them. I believe they\nwill not be happy with a 60 cm dish but will require a much larger dish\nto be happy and I am certain they would do it. I do not care. They are\nnot who I am computing for. These are not the customers I am trying to\nserve. The customers I want to serve for the future of AMSAT cannot be\nserved by a scratchy SSB signal and a (now) 4 foot dish. I have a\nmission directive from the board of directors you elected and voted for\nto serve these NEW customers. Those who will be here when the third\nsatellite is launched. They will not be where Dave will be by then. I\napologize for the crassness of this remark, but I am trying to make a\npoint. I know Dave and have for nearly 30 years.. We are building for\na guessed audience, with a guessed legal and RF environment, with a\nguessed ability to deliver 3 such payloads over the next 13 years.\n\nCOLD HARD CALCULATION went into this analysis based on our best guesses\nand analyses. Given what we believe the environment will be We can\nonly do this on microwaves and we can only do it digitally. PERIOD.\nEnd of story. God (as demonstrated through the mathematics of Claude\nShannon) has dictated this outcome. We did not sit in a back room and\ndecide what new toys we would throw your way to delight ourselves and to\nscrew you (no more smoke and no more drink in there, we have grown old\nand boring) . To do it, I have to build a very complex antenna system\nthat will take up most of the available area on the spacecraft for\nantennas. I cannot build a three axis stabilized spacecraft (I do not\nhave the team or the money to do it), so I must do it with phased\narrays. Matt Ettus has given us a great head start on this design and\nTom Clark and John Stephensen have done great work on the antennas so\nfar. We will test these antenna designs in the next twelve months\nthanks to a very generous antenna test range offer and design help by\none of our members.\n\nThe direction Jim and I gave our engineering team was that we cannot\nrely on this to work perfectly and meet every operational goal\nperfectly. STUFF HAPPENS. We are attempting to be ambitious but we\nabsolutely must have a credible back up in case this system does not\nmeet our expectations. We now have the upgraded Mode B transponder\ndesign which I believe will be the sweetest one flown since Oscar 7's\nMode B. Fully equipped with the channelized AGC (Leila or Stella),\ngenerating HELAPS with modern technology and new fantastic amplifier\ncomponents.\n\nI gave the argument to our engineering team that I have witnessed one\nexperimental, new widget after another get built, flown, and then have\nits designers disheartened and dejected because it got \"RUDAK'ed\". It\nnever really gets used or fully developed. It drifts into an inert lump\nthat people mumble about when they are asked of their involvement. I\ninsisted on enough spacecraft power generation to run BOTH the linear\ntransponder and the digital transponder simultaneously and 365 days a\nyear, EVERY year. This is the single most expensive decision we have\nmade. We might spend 1/2 to 3/4 MILLION dollars on solar panels to\naccomplish this. I have insisted we have enough antenna space to make\nall of the antennas credible and based on calculation of the required\nantenna gains to close the links. Again, Claude Shannon has\ninterpreted the natural laws and dictated the outcome. Cold hard\ncalculation has gone into the needed solar generators, and the size of\nspacecraft required to support this.\n\nIt will be about 4 feet across and look initially like a scaled DOWN\nAO-40 at launch if the concept becomes our design.\n\nWe cannot deliver the quality of services we are demanding of ourselves\nif we fly all of the bands to be flown on P3E. We do not have the power\nor the antenna territory to meet our goals for these services.\n\nI have taken my direction from the board of directors of this\norganization. They made the vision statement. They can change it. You\nelected them.\n\nSeveral things will happen in October. We will install four\ndirectors. I may, or may not, be one of them. The board will vote\nwhether or not to retain me as the VP Engineering. I have made almost\nNO ONE happy by slowing down those who drive me crazy with wanting to\nrush head long in a ready fire aim approach by demanding that we\ncalculate our way to the vision statement to show the directors the\nconsequences of the decision making processes. I have to tell you, I\nam damn proud of how much has been done in eleven months. Stuff got\nput on hold that aggravated many. We all make decisions about the way\nthings have to go but I have done my best to aim us in a technically\nfeasible direction. I do not have time to do all the everyone wants me\nto do. I will continue to do my best if I stay in the job.\n\nI offer the following. If the board votes to change their vision\nstatement and not to build the spacecraft we are proposing, I will\ntender my resignation as VP Engineering since I will have failed to do\nthe job they elected me to do which was to produce a usable concept to\nmeet their vision. I am not interested in flying a carbon copy of P3E\nwhen I know it makes no sense whatsoever. I am 52 years old and one of\nthe most active technical contributors in all of amateur radio. I will\nnot waste my time doing what I know in my heart and my head is not in\nthe best interests of amateur radio even if it is currently perceived to\nbe for the good of the shrinking aging membership of AMSAT. It would\nbe irresponsible of me not to attempt to aid the organization in\naddressing a new group of members while attempting to thread the needle\nof serving our current members. If elected to the board, and it changes\ndirection, I will offer my seat to the first alternate. Vote for\nsomeone else if you do not want P3E built and you do not want the AMSAT\nvision statement attempted if you have not cast your vote.\n\nThe story you have just been told should not have come out in this\nform. It was NEVER meant to be displayed in this form. The\ncalculations were made at the first of July. They have undergone\nseveral iterations and were not really put in there latest form until\nAugust. In an attempt to get further interest from the microwave\ncommunity, we made a decision to give a sneak peek to get some technical\naid from RF specialists. This has backfired badly because we, the\nvolunteers who have sacrificed countless hours on your behalf, have not\nhad the time to put together a hundred pages of supporting documentation\nto tell the story in a coherent fashion so not only do we look like\nidiots, we have had to do things like waste 3.5 hours writing this\nsilly note when I should have been asleep.\n\nLastly. I have been accused here of being a con artist. I resent\nit. I don't need to con anyone. Frankly, I don't have to be here at\nall. I choose to be.\n\nBob\nN4HY\n\n--\nAMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,\nNJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman\n\"You see, wire telegraph is a kind of a very, very long cat.\nYou pull his tail in New York and his head is meowing in Los\nAngeles. Do you understand this? And radio operates exactly\nthe same way: you send signals here, they receive them there.\nThe only difference is that there is no cat.\" - Einstein\n\n_______________________________________________\nSent via [email protected]. Opinions expressed are those of the author.\nNot an AMSAT-NA member? Join now to support the amateur satellite program!\nSubscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n\n", "attachments": [] }