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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/VKFV4C7XEUTZID4BK4EAVTN6DQWRFORK/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "CAKXf1rEtLbSUHLrP2fAWOL5pQTkPRLL4_pOK2y6Msc2kGDEMsw@mail.gmail.com",
    "message_id_hash": "VKFV4C7XEUTZID4BK4EAVTN6DQWRFORK",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/S37GLW3P66IUKVK54AQXDNOMKF2YEMNK/",
    "sender": {
        "address": "pa3weg (a) amsat.org",
        "mailman_id": "2d7e27ec560548fe9bb52af1b2c45c3e",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/2d7e27ec560548fe9bb52af1b2c45c3e/emails/"
    },
    "sender_name": "wouter weggelaar",
    "subject": "[amsat-bb] Re: AO-73 QSOs on the beacon?",
    "date": "2013-12-07T12:06:24Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/S37GLW3P66IUKVK54AQXDNOMKF2YEMNK/",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi All,\n\n>From a design perspective, the transponder would require about 30 to 40dB\nmore uplink power to produce a signal overlapping the telemetry. That\nsignal would then be a maximum of 9dB above telemetry, compared to the rest\nof the transponder. Since the transponder is used, the power spreads\nbetween users, further reducing the effect.\n\nThe telemetry signal and transponder are combined, with the telemetry\nstepped down 9dB, and the filter rejection for the transponder at the\ntelemetry frequency is better than 30dB (40dB with some ripple, I measured\n35dB rejection on the engineering model)\n\nThe AGC acts on the composite output, so if no-one is on the main passband,\nthe transponder will start running full gain (43dB extra). This will\npossibly reduce the required uplink power to actually overlap the\ntelemetry. But this only happens on high power uplinks combined with no-one\nrunning in the main passband.\n\nAs soon as someone triggers the AGC with a signal in the main passband, the\nAGC will kill the overlap.\nThere also is FM-ing of the telemetry beacon, but this effect is small\n(~100Hz), and the BPSK decoder can cope with it.\n\nI think it is more likely that AO-7 was up, or some local intermod is\nproducing this effect, but this effect being on the satellite can not be\ncompletely excluded. Thanks for sharing this information!\n\nWouter PA3WEG\nFUNcube RF Board designer\n\n\nOn Sat, Dec 7, 2013 at 8:25 AM, Michael Fletcher <[email protected]> wrote:\n\n>\n>     Subject: [amsat-bb] Re: AO-73 QSOs on the beacon?\n>>    From: Michael Fletcher <oh2aue@xxxxxxxxxxx>\n>>    Date: Fri, 6 Dec 2013 08:55:41 +0200 (EET)\n>>\n>>\n>> AO-7, mode B, happens pretty often...\n>>\n>\n> As I noted earlier, the only few times I have heard traffic _on_\n> the AO-73  beacon frequency is when AO-7 is above the horizon\n> in the sun and in Mode B. VO-52 downlink traffic comes close too\n> occasionally, due to Doppler and orbits, but not _onto_ the beacon per se.\n>\n> And my ancient FCD is running just fine, with a highly selective\n> HB LNA and a very sharp multicavity notch for my local APRS\n> repeater at 144.800 MHz.\n>\n> Michael OH2AUE\n>\n>\n> --\n>\n>\n>\n> _______________________________________________\n> Sent via [email protected]. Opinions expressed are those of the author.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n>\n",
    "attachments": []
}