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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/3HNF6DMI5P3KUSGUQV3O5VRYSYCOWNDU/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "3HNF6DMI5P3KUSGUQV3O5VRYSYCOWNDU",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/3HOBEX6G2BEGIWMKM6QRTK6HQYE65LZN/?format=api",
    "sender": {
        "address": "oz1my (a) privat.dk",
        "mailman_id": "b2f56900318d4d1193159750f39aa3fe",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/b2f56900318d4d1193159750f39aa3fe/emails/?format=api"
    },
    "sender_name": "OZ1MY",
    "subject": "[amsat-bb] Re: Linear link budgets",
    "date": "2007-01-05T17:47:58Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/3HOBEX6G2BEGIWMKM6QRTK6HQYE65LZN/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi Grant and all,\nYes you are right about the PEP - but it is not as\nbad as that if we take statistics into account.\n10 stations are not likely to transmit at the same\ntime.\nAs far as I remember AMSAT-DL used the square root\nof the number of users as a good indication of how\nmany users there can be on a linear transponder to\ncalculate the power for each user.\nHave a nice weekend\n73 OZ1MY\nIb\n----- Original Message ----- \nFrom: \"Grant Hodgson\" <[email protected]>\nTo: <[email protected]>\nSent: Friday, January 05, 2007 11:35 AM\nSubject: [amsat-bb] Linear link budgets\n\n\n> Unfortunately, the calculations for dividing transponder power equally\n> amongst users are not as simple as have been suggested.\n>\n> For the 400mW case :- assume that 400mW is the maximum power that the\n> transmitter can produce.  Then a single CW signal could in theory be\n> sent at a power of 400mW, assuming no AGC, beacons etc.\n>\n> However, if 2 equal level CW signals were being transmitted, then the\n> Peak Envelope Power of these 2 signals would be 6dB higher than each of\n> the signals individually.  This is because the voltages of each of the 2\n> CW signals have to be added together, giving a peak signal with double\n> the voltage of each signal, which is 4 times the power or a 6dB increase.\n>\n> Therefore, to keep within the 400mW limit, each CW signal would be\n> restricted to 100mW each.  The same analysis can be done for 3 equal CW\n> signals, where each would be 9.5dB down; i.e. 44mW each etc.\n>\n> For SSB signals, the same analysis can be performed by simply taking the\n> PEP of each SSB signal; so one CW signal could co-exist with one SSB\n> signal, both of which would have a downlink power of 100mW.\n>\n> The above is actually a slight over-simplification, as it takes no\n> account for compression etc, but serves as a useful example.\n>\n> As Graham mentions, a beacon may be present at a much higher level than\n> the rest of the transponder, which makes the analysis slightly more\n> complex, but the principle remains :-\n>\n> It's the PEAK power that limits the RF performance of linear\n> transmitters, and that is valid for all linear transmitters.\n>\n> regards\n>\n> Grant  G8UBN\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\n\n",
    "attachments": []
}