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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/JUIXC5RCOOBMHKDFWN4T6MORIGGS4AUJ/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "JUIXC5RCOOBMHKDFWN4T6MORIGGS4AUJ",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/UADPJ2VQ2C65E6QYNMVNYV3YIMVTUMKU/?format=api",
    "sender": {
        "address": "dquagliana (a) aol.com",
        "mailman_id": "75c9beaffd1d4a0cb28236652097bbb0",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/75c9beaffd1d4a0cb28236652097bbb0/emails/?format=api"
    },
    "sender_name": "Douglas Quagliana",
    "subject": "[amsat-bb] Re: Digital modes and antenna questions",
    "date": "2007-04-28T23:59:11Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MUEKS64MQKGLX33KN7Z7P3GITAEFNEUB/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi guys,\n\nRod asks:\n > Also decoding telemetry from the birds, is there a\n > \"one size fits all\" software or does each satellite\n > have specialized software for doing this?\n\nThere is no one single program that does everything\nfor every amateur radio satellite.\n\nHowever, you can do much of the work completely in\nsoftware. For example, when AO-40 was still active it\nwas common to receive the 400 bps telemetry signal\nwith your radio, then demodulate the signal with\na soundcard and AO40Rcv (software) and then display\nthe telemetry with P3T, another piece of software.\nThese days you can accomplish a similar feat for\ncurrently active satellites like AO-51, albeit using\ntotally different software packages.\n\nIf you're really interested in digital satellite modes\nyou might want to check out the AMSAT Digital CDROM -\nit comes with several digital program and test\nsignals for everything from 1200 baud to 38k4 baud.\n(Disclaimer: I had a hand in the making of a couple\nof the items on the CDROM.)\n\[email protected] wrote:\n> Apparently nobody has yet written software that can\n> demodulate 38600 bps (or 38k6). \n\nActually, it's 38,400 bps (38k4) and, yes, there is\nsoftware that will demodulate the signal using only a\nsoundcard. I know because I wrote it. :-) For my\nversion, see the paper \"A First Look at a New\nSoundcard DSP Modem for Satellite Telemetry\" in the\n2005 AMSAT Symposium Proceedings, or just email me\nwith your questions.\n\nThe 38,400 bps signal will just fit into the bandwidth\nof a soundcard running at 48,000 samples per second.\n(No, this doesn't violate Nyquist.)\n\nAnd I'm not the only one to write software for 38k4.\nThere's also a 38k4 DSP modem for the DSP56002EVM,\nif you have one of those. (I don't.) See\n\nhttp://bips.bi.ehu.es/prj/modem/tossa/index.html\n\nfor their 38k4 software modem that runs on a\nDSP56002EVM. There's probably others too.\n\nThe tricky part, in my opinion, is receiving the\n38k4 signal and getting it (undistorted) into the\nsoundcard. At RF you need a very wide filter to\npass the whole FM signal, and as an audio signal,\nits spectrum goes from almost zero Hertz up to\n19,200 Hertz. Some FM receiver chips, which would\nwork fine at 9600 baud, have a frequency response\nthat cuts off before 19,200 Hertz. With the effects\nfrom the RF filter, and the FM receiver chip\ncombined, in some receivers the 38k4 signal will\nnever make it to the soundcard. But I digress...\n\nAnybody know a good drop in replacement for\nsomething like an MC13135P that would work up\npast 20,000 Hertz?\n\nDouglas KA2UPW/5\n",
    "attachments": []
}