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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MWZYQT6RWFFT2LQ5VP5I2EEOEB7GSGKQ/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "MWZYQT6RWFFT2LQ5VP5I2EEOEB7GSGKQ",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/YUKH4DQ77SUSHNVLE4ZNNW6R2PFZPWJD/?format=api",
    "sender": {
        "address": "zleffke (a) vt.edu",
        "mailman_id": "57a24afb1cf641f98121841e6753c12e",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/57a24afb1cf641f98121841e6753c12e/emails/?format=api"
    },
    "sender_name": "Zach Leffke",
    "subject": "Re: [amsat-bb] FM signal on FO-29?",
    "date": "2015-11-08T22:13:27Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/TENXDYXNF5DCS2MS75KHLC2DOWOVPBR4/?format=api",
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/PKQUJBULU3RJJPG65ANMONI24NJAGGKB/?format=api"
    ],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi Rick,\n     I've been monitoring FO-29 on and off for the last few weeks as \npart of my AO-73 to FO-29 cross link experimentation.  I have \nconsistently seen FM on FO-29.  In fact I played a video at the AMSAT \nsymposium where I pointed it out in a spectral display (FFT and \nWaterfall) of the FO-29 downlink.  We can see the entire noise floor of \nFO-29's passband with the VTGS setup, and when the FM activity jumps up, \nyou can see the entire passband of the transponder drop in power as the \nFM signal sucks up all the power of the transponder.\n\nI have detected, but have yet to decode AO-73's tlm beacon via FO-29.  \nRight now I'm operating on a weak crosslink signal theory as the reason \nfor failed decodes.  I can hear FO-29 just fine (in fact VERY strong at \nVTGS), but AO-73 is barely making it into the uplink passband.  I've \ncome up with a simulation tool thats a mixture of STK output data and \npython that tells me when chain events will occur (a chain being AO-73 \nto FO29 to VTGS) and a whole bunch of other info like doppler offsets, \ncrosslink path loss, etc.\n\nIn fact, this last Friday, around 1357 Eastern time, was one of the best \nopportunities to catch AO-73 via FO-29, in terms of minimum crosslink \npath loss, in a two week window.  At the beginning of the FO-29 pass \nthere was LOTS of FM activity on FO-29.  I was cursing and pulling my \nhair out (to the dismay of the students who were watching) because I was \nworried that the FM activity would suck up resources on the transponder \nright when I'm hunting for a weak signal on the bird.  BUT... as the \nsatellite continued through the pass (an ascending pass) the FM activity \ndied down, which was good for my experiment because the AO73 chain event \nwas about the last 300 seconds or so of the pass.  I still didn't decode \n(though I *think* I detected AO-73, I need to review the capture file \nmore) because doppler shift had the AO-73 signal sweeping right through \nthe center of FO-29's passband, where there was lots of normal SSB activity.\n\nSo yes, in the last couple weeks I've seen a LOT of FM activity on \nFO-29.  And based on my experience with Friday's pass, which was \nascending, I'm leading towards the Central/South America QRM theory.  \nLots of strong FM activity as the pass started and the satellite was \nover the lower latitudes, but as FO-29 ascended over higher latitudes \ntowards the north pole, the FM activity died down.\n\n-Zach, KJ4QLP\n\nOn 11/08/2015 03:25 PM, Jim Jerzycke wrote:\n> On 11/08/2015 07:03 PM, Rick Walter wrote:\n>> I was just on the 18:44 Z pass of FO-29 and was certain I heard an FM\n>> signal around 435.869. There was a loud squeal and it sounded like an \n>> alien\n>> was talking! Should I get my hearing checked or did anyone else notice?\n>> Thanks.\n>> Rick - WB3CSY in FN10\n>>\n> I've heard FM on FO-29 before, but it's been a while. I forget if it \n> was a Ham, or a Mexican/South American taxi or similar.\n>\n> 73, Jim  KQ6EA\n> _______________________________________________\n> Sent via [email protected]. AMSAT-NA makes this open forum available\n> to all interested persons worldwide without requiring membership. \n> Opinions expressed\n> are solely those of the author, and do not reflect the official views \n> of AMSAT-NA.\n> Not an AMSAT-NA member? Join now to support the amateur satellite \n> program!\n> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb\n\n",
    "attachments": []
}