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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/BH6LUBV7AWWJMF2LPUTJ6WIHROHXI722/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "BH6LUBV7AWWJMF2LPUTJ6WIHROHXI722",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/34RBN2KKUJXQT3HLVTI56C2I6IMW5X6Z/?format=api",
    "sender": {
        "address": "ronoverdrive (a) tehfurry.com",
        "mailman_id": "813484ce2b5442148f5f100f58809600",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/813484ce2b5442148f5f100f58809600/emails/?format=api"
    },
    "sender_name": "Ron Overdrive",
    "subject": "[amsat-bb] Re: SO-67 back on air!",
    "date": "2010-06-21T14:41:25Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/34RBN2KKUJXQT3HLVTI56C2I6IMW5X6Z/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Honestly sounds like a good way to keep people from doubling/tripling up on\neach other. Might end up making more contacts per pass if everyone is forced\nto wait between transmissions to be heard.\n\nOn Mon, Jun 21, 2010 at 10:04 AM, Jan-Albert Koekemoer <\[email protected]> wrote:\n\n> Hello\n>\n>\n>\n> After much delay we are now in a position to re-activate the SA-AMSAT\n> payload\n> schedules on a regular basis again!\n>\n>\n>\n> During the downtime we conducted several experiments in order to\n> investigate\n> possible alternatives for the \"cut-off\" problem experienced by many at the\n> end of last year / beginning of this year.  The cut-off is caused by SW\n> running on piggyback electronics that continues to gate the received audio\n> onto the transmitter for about 3s after a specific ground transmission has\n> ended, whereafter the received audio is cut off.  The SW then waits for the\n> next ground transmission with a valid \"transponder\" tone embedded, before\n> gating the audio onto the transmitter again.  So if a second transmission\n> starts within the 3s \"tail\" period, it will be cut off when the 3s expires.\n> Listen to this mp3 recording as an example:  http://tinyurl.com/38vvg3o\n>\n>\n>\n> Unfortunately the piggyback electronics does not have reprogramming\n> functionality, so we are not able to change the SW.  We did however manage\n> to\n> implement a mechanism on the satellite transponder (used by the piggyback)\n> that should be of some assistance when using the payload:  the PTT of the\n> transmitter now STAYS ON for the duration of the payload activation (i.e.\n> 15\n> min), regardless of a valid \"transponder\" tone received.  Note that this\n> does\n> not get rid of the \"cut-off\" problem, nor of the requirement to embed a\n> valid\n> tone when you want to use the payload - see detailed explanation below.\n>\n>\n>\n> The following example depicts the ideal usage scenario of the payload:\n>\n> 1.       As the satellite comes over the horizon, an unmodulated carrier\n> (\"quieting\") will be received by all on UHF\n>\n> 2.       Person A starts to transmit on VHF (with valid \"transponding\" tone\n> embedded in the transmission) and the transmission is relayed on UHF\n>\n> 3.       When Person A releases his/her PTT, the satellite will continue to\n> transmit what it is receiving (usually this will be \"noise\") for a further\n> ±3s.  Nobody should start to transmit during this time!\n>\n> 4.       At the end of the ±3s period, everybody will again hear the\n> unmodulated carrier.\n>\n> 5.       NB: only when this unmodulated carrier is heard should Person B\n> start to transmit.  Listen to this mp3 recording as an example of valid\n> usage:  http://tinyurl.com/32rjbxm\n>\n>\n>\n> I suppose this will take some getting use to - at least the system has a\n> built-in \"punishment\" mechanism for the impatient! ;-)\n>\n>\n>\n> Please refer to previous posts on general voice quality optimization when\n> using the SA-AMSAT payload on SO-67.\n>\n>\n>\n> I will request Gladys Magagula at the Satellite Application Centre to\n> obtain\n> regular schedules from the regional coordinators as soon as possible.  We\n> will start off with day passes only, transmit on 2.5W and see how things\n> go.\n>\n>\n>\n> Enjoy!\n>\n>\n>\n> Regards\n> Jan-Albert\n>\n>\n>\n> ________________________________________\n>\n> Jan-Albert Koekemoer, PrEng\n>\n> Sun Space & Information Systems (Pty) Ltd.\n>\n> Stellenbosch, South Africa\n>\n> www.sunspace.co.za <http://www.sunspace.co.za>\n>\n> +27 21 880 8117 (tel)\n>\n> +27 83 461 6643 (cell)\n>\n> +27 21 880 1703 (fax)\n>\n>\n>\n>\n>\n> E-mail Disclaimer\n> http://www.sunspace.co.za/emaildisclaimer.htm\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": []
}