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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/Y3JY73MBBQJI3NUQ4EJSWTM7Q7DUMJQL/?format=api", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api", "message_id": "[email protected]", "message_id_hash": "Y3JY73MBBQJI3NUQ4EJSWTM7Q7DUMJQL", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/3K67Q7IKPL5Y2RIXFGNHB6TBX4IYMCMD/?format=api", "sender": { "address": "rwmcgwier (a) comcast.net", "mailman_id": null, "emails": null }, "sender_name": "Robert McGwier", "subject": "[eagle] Re: DCP Bands", "date": "2006-09-11T03:18:07Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/QOOOVY4QINW76HJ2JCKCL5AUWA6YDR2S/?format=api", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "Thanks for sending this. I received no traffic from amsat.org between \n9/8 at 4 AM and 4:57 AM this morning. Comcast had amsat.org blackballed.\n\nI would not have known Matt sent this note without the inclusion.\n\nIt is just amazing to me what a land mine microwave has become. In the \nend, we are going to have to choose the best of no good options.\n\nNo one is frustrated with this more than me.\n\nBob\n\n\nJim Sanford wrote:\n> Matt:\n> I think you have done a nice job of condensing what we discussed there, \n> or at least what I heard and captured in my notes.\n>\n> Well done.\n>\n> 73,\n> Jim\n> [email protected]\n>\n>\n> Matt Ettus wrote:\n>\n> \n>> In the time since the San Diego meeting, I have come to realize that:\n>>\n>> 1 - Nothing is ever final.\n>>\n>> 2 - The decision about bands for the DCP (digital communications \n>> payload) is likely to be made in some combination of the following \n>> venues, in none of which you are likely to find me:\n>> A - AMSAT-BB\n>> B - AMSAT Board Meetings\n>> C - Meetings with shadowy DoD figures without names\n>> D - IARU, ITU, ARRL, QCWA, or Wuoff-Hong Society meetings\n>>\n>> 3 - Many of the decision makers (especially those speaking the loudest) \n>> think that SSB is the way of the future and Shannon's Law means that sex \n>> offenders have to register with the police.\n>>\n>> 4 - It really doesn't matter to me which bands are chosen, as long as \n>> they meet certain basic criteria.\n>>\n>> In that spirit, I decided to distill the major technical constraints \n>> which we agreed on at the San Diego meeting, in order to give a basic \n>> set of rules which would provide us a workable bandplan for this \n>> satellite. The only legal/regulatory constraint I applied to this list \n>> is that we are unlikely to GAIN privileges. Someone else can decide how \n>> likely we are to lose them.\n>>\n>> The constraints, and their reasons, as I see the consensus from the SD \n>> meeting:\n>>\n>> 1 - The uplink band must be chosen from the set of { L, S1, S2, C }.\n>> The lower bands simply don't have the bandwidth necessary for what \n>> we want to do, and would have unwieldy antennas.\n>> The higher bands are much more difficult due to the pointing \n>> accuracy required for antennas and the difficulty of generating \n>> significant power and low noise figures.\n>>\n>> 2 - The downlink band must be chose from the set of { S1, S2, C }.\n>> The same reasons as constraint #1, with the added constraint that \n>> L-band is not legal for downlink (which falls under the \"we're not \n>> likely to GAIN privileges\" category).\n>>\n>> 3 - The uplink and downlink bands must be distinct. This means no C-C \n>> or S1-S1.\n>> The bands are simply too narrow to allow for practical duplexers in \n>> the quantity we are talking about (~36).\n>>\n>> 4 - The uplink band must not be used by any other payload on Eagle as a \n>> downlink.\n>> Obvious interference issues.\n>>\n>> 5 - The downlink band should not be used by any other payload as an uplink.\n>> Obvious interference issues.\n>>\n>> 6 - Sharing of uplink bands or downlink bands MAY be possible, but \n>> probably isn't necessary.\n>>\n>> Taking constraints 1-6 together, the choices are (in the form A/B where \n>> A is up, B is down):\n>> { L/S1, L/S2, L/C, S1/S2, S1/C, S2/S1, S2/C, C/S1, C/S2 }\n>>\n>>\n>> In addition to the above \"hard facts\", we can add in the following \n>> concerns which were expressed at the meeting:\n>>\n>> 7 - We would prefer not to use S1 as a downlink because of possible \n>> interference from WiFi devices.\n>> 8 - Fear of L being taken away\n>> 9 - Uncertain legality of S2 in ITU Region 1\n>>\n>> This leads to the following matrix, which I believe effectively boils \n>> down the decision process from the SD meeting:\n>>\n>> Bandplan 7 8 9\n>> L/S1 X X\n>> L/S2 X X\n>> L/C X\n>> S1/S2 X\n>> S1/C \n>> S2/S1 X X\n>> S2/C X\n>> C/S1 X\n>> C/S2 X \n>>\n>> The only bandplan with no X's is S1/C, which is what we chose at the \n>> meeting. Obviously, there are now additional concerns which have been \n>> raised:\n>> - S1-Uplink being taken away\n>> - #8 not being as big a deal as we thought. \n>>\n>> This would change the matrix.\n>>\n>> I welcome your thoughts, especially if you feel I have misrepresented \n>> the SD meeting consensus.\n>>\n>> Thanks,\n>> Matt, N2MJI\n>>\n>> _______________________________________________\n>> Via the Eagle mailing list courtesy of AMSAT-NA\n>> [email protected]\n>> http://amsat.org/mailman/listinfo/eagle\n>>\n>> \n>>\n>> \n> _______________________________________________\n> Via the Eagle mailing list courtesy of AMSAT-NA\n> [email protected]\n> http://amsat.org/mailman/listinfo/eagle\n>\n> \n\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", "attachments": [] }