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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/SYJJLNRMIDUCNBX4TCLJRLA4VGMARMAF/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "SYJJLNRMIDUCNBX4TCLJRLA4VGMARMAF",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/VCDTMBIXHRBZ2VBNHJORBFZIX3HQFHWY/",
    "sender": {
        "address": "nate (a) natetech.com",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Nate Duehr",
    "subject": "[amsat-bb] AO-16 & FM receiver thoughts (was: AO-16 report from\tCopenhagen)",
    "date": "2008-01-26T10:06:20Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/VCDTMBIXHRBZ2VBNHJORBFZIX3HQFHWY/",
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/DFTPXQCNOOVV3DEYL2MUOH5ZXOQ5YGM4/"
    ],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "\nOn Jan 23, 2008, at 11:14 PM, Tom Clark, K3IO wrote:\n\n> The receiver has a 15 kHz wide crystal filter with sharp skirts. So if\n> your NBFM xmtr is set with a ±5 kHz deviation, you may well find your\n> signal hitting the filter \"walls\". You may get better performance if  \n> you\n> crank the deviation back a bit.\n\nLots of folks who haven't worked on FM repeaters (or repeater  \ncoordination) don't realize that a 5 KHz deviation signal actually  \noccupies 16 KHz, Tom.  This is a great reminder, and knowing there's a  \nsharp-skirted 15 KHz filter is great info for folks trying.\n\n(Sadly, lots of repeater users don't know the difference between  \n\"deviation\" and \"modulation\" these days, either -- but that's a whole  \ndifferent rant...)\n\nThis would also mean that if you're way off on correcting for doppler  \non the uplink you could ram into the skirts of the filter too... on  \nmodern rigs, go into those menus and set that FM step for as small a  \nnumber as it'll go, and play around folks... you might find that fine  \ntuning things a bit the correct direction for the doppler on the  \nuplink might help a bit too.\n\nA little lower deviation and a little more tuning and fiddling as  \nneeded with the uplink frequency, and voila!\n\nAnyway this leads me to a thought, Tom -- for those who have modern FM  \nrigs that have so-called \"narrowband\" mode (usually max 2.5 KHz  \ndeviation) would the satellite's FM receiver be fairly linear when fed  \nwith low deviation levels?  I know it hurts on S/N ratio on the DSB  \ndownlink, but would 2.5 KHz deviation yield 50% modulation of the DSB  \ntransmitter, or is the FM receiver's audio output non-linear to some  \nextent (like most are) and 2.5 KHz deviation would really be down to  \nsomething like 30-40% modulated on the downlink?\n\nIt'd keep people from hitting the filter skirts as much, but if it  \nyields really low modulation levels of the DSB transmitter, it'd  \nprobably hurt more than it would help.  What do you think from what  \nyou know of the ol' girl's FM receiver audio setup?  Any thoughts?   \nWorth experimenting with the feature if folks rigs have that setting?\n\nNeat stuff seeing the reports of those playing with the bird since she  \ncame back to life, both the control stations folks who did their  \nmagic, and now the end-users.  Cool to read along!\n\n--\nNate Duehr, WY0X\[email protected]\n\n\n\n",
    "attachments": []
}