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    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/D7DWUURKWBDSFPR3Z65M2NLJOWM2NY5S/?format=api",
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    "message_id": "[email protected]",
    "message_id_hash": "D7DWUURKWBDSFPR3Z65M2NLJOWM2NY5S",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/DNIFMRNNSZ7S7QW6RV73AQ77G4NWPEMO/?format=api",
    "sender": {
        "address": "wb4gcs (a) amsat.org",
        "mailman_id": "87014499e012476c8198fad186f7f963",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/87014499e012476c8198fad186f7f963/emails/?format=api"
    },
    "sender_name": "Jim Sanford",
    "subject": "[eagle] Re: Module Temperatures",
    "date": "2006-10-14T14:15:20Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MITW4EAYMVBGNCTZCLKSK27GABCGQN6J/?format=api",
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/L7GAR5KQOIWF5M5HM6AR7IGBYQZGWQFR/?format=api"
    ],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "\nWill we share antennas or add some?\nJim\n\n\nRobert McGwier wrote:\n\n>I believe we should use Mirek's command receiver on L band as adapted \n>for our purposes.  If we want a redundant one for any reason,  we do \n>that one on 70cm.  The command receiver should feed the IHU-3 SDR for \n>any normal commanding and any reset vector decoder we choose to enable.\n>\n>The issue is straightforward.   Any module that needs a heat sink will \n>have been designed to be kept cool when the spacecraft is receiving a \n>large thermal input from the sun.  When this thermal input is removed,  \n>the same radiation cooling that was keeping the module cool will  \n>continue to operate irrespective of the solar input.  That module will \n>get cold over time.  If the bottom temperature stops the unit from \n>operating properly and it is a command receiver,  this is not a good \n>thing.   I believe we should have dedicated command receivers anyway and \n>these to do not need 80 dB of dynamic range and can be made narrow \n>band.  Our solar eclipse pattern has been given a preliminary analysis \n>for the proposed orbit and we will be subjected to eclipses of \n>insufficient duration to cause us severe thermal problems but what \n>thermal issues there are need to be understood and this is what Dick is \n>warning us about.  This analysis of the eclipse pattern was also the \n>basis of my analysis that it would take well over a decade to subject \n>any Li-ion battery to sufficient cycles to worry about.\n>\n>Bob\n>N4HY\n>\n>\n>John B. Stephensen wrote:\n>  \n>\n>>The SAW filters work down to -35 C and the ICs to -40 C so its not too \n>>far off. It's easy to use a lower power RF amplifier and mixer which \n>>will lower the input intercept. Right now, the receiver is designed to \n>>tolerate direct hits from PAVE PAWS at any two frequencies outside the \n>>IF passband. As the input intecept is lowered, the percentage of \n>>pulses that cause interference increases, but the receiver won't go \n>>completely deaf as was reported on earlier satelites.\n>> \n>>73,\n>> \n>>John\n>>KD6OZH\n>>\n>>    ----- Original Message -----\n>>    *From:* Dick Jansson-rr <mailto:[email protected]>\n>>    *To:* AMSAT Eagle <mailto:[email protected]>\n>>    *Sent:* Wednesday, October 11, 2006 17:51 UTC\n>>    *Subject:* [eagle] Module Temperatures\n>>\n>>    Last evening I tried to convey the concept that the\n>>    critical-command modules needed to be of low-power design to\n>>    insure their operability during the occasional rather lengthy\n>>    eclipse cooling of the spacecraft. My message apparently did not\n>>    sink in. John reports that his design of such a U band receiver\n>>    would be dissipating some 3.5W due to its bullet-proof nature\n>>    against 3rd-order IM products needed for protection on the U band.\n>>     \n>>    If we go forward with such a module of that nature, it will need\n>>    to have thermal control tapes on it to provide a mean emittance of\n>>    about e=0.45. In a 3 hour eclipse we can expect to see spaceframe\n>>    temperatures down to -100°C (173K) or lower. With such an\n>>    environment John's module would be expected to see temperatures\n>>    down to at least -44°C, which is a bit frosty for electronics that\n>>    are expected to provide the critical services of commanding the\n>>    spacecraft. Such operating temperatures are not felt to be\n>>    advisable for that service.\n>>     \n>>    If John's module were of the 1W category, temperatures of the\n>>    receiver could be expected to be in the range of -15°C to -20°C\n>>    which would be more operable for the service.\n>>     \n>>    The above numbers are, of course, based on estimates which will be\n>>    confirmed after we have the new spaceframe fully designed and\n>>    analyzed. The \"warmer\" temperatures of the lower power modules are\n>>    those that have been experienced and measured by telemetry from\n>>    AO-10 and AO-13. These projections are thus based on 25 years of\n>>    experience in these design concepts.\n>>     \n>>    /Dick Jansson/\n>>    _---------------------------_\n>>    [email protected] <mailto:[email protected]>\n>>    _---------------------------_\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>>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>  \n>\n\n\n",
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