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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MG2EL4HGO6VJEAMIBF2JYC4C7HGELR6B/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "MG2EL4HGO6VJEAMIBF2JYC4C7HGELR6B",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/MG2EL4HGO6VJEAMIBF2JYC4C7HGELR6B/",
    "sender": {
        "address": "avollhar (a) physik.uzh.ch",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Achim Vollhardt",
    "subject": "[amsat-bb] Re: requesting help on a RF link solution (imaginary, ka-band link!)",
    "date": "2009-10-27T17:09:36Z",
    "parent": null,
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi Samundra,\n\ndon't see which path loss you assumed, but for 1 AU (149 mill km), I \ncalculate 286 dB @32 GHz.\n\nAlso 3000K seems much to bad.. assume 300K.\n\nSo let's add up for 1 AU:\n\n40 dBm (10W) +2x56.4 dBi -286 = -133.2 dBm at RX input\n\n1 Gbit/s assumes 1 GHz bandwidth. 300K is roughly -174 dBm/Hz.\n1 GHz = 60dB worse = -116 dBm.\n\nSo you end up with -133.2 - (-116) = -17.4 Eb/No.. not good.\n\nIf you add 20dB you end up at 2.6 dB Eb/No. Not brilliant, but close. \n20dB means 0.1 AU instead of 1 AU = 14.9 Mill km.\n\nI think your result was 4.6E9 m (!), not km.. which is 4.6 mill km. \nShould be it, if getting back to your assumed 3000K RX.\n\n\n73s Achim, DH2VA\n\n\n\n> Date: Tue, 27 Oct 2009 06:03:30 -0400\n> From: Samudra Haque <[email protected]>\n> Subject: [amsat-bb] requesting help on a RF link solution (imaginary\n> \tka-band\tlink!)\n> To: Amsat-bb <[email protected]>\n> Message-ID:\n> \t<[email protected]>\n> Content-Type: text/plain; charset=ISO-8859-1\n> \n> Hi, amsat-bb\n> \n> CQ any satellite link budget expert !\n> \n> I'm trying to do a calculation on my own based upon published specs\n> for the NASA MRO Ka-band experiment, but am getting some unexpected\n> results for a Ka-band simplex link with Temp=3000K (hypothetical),\n> operating with a Signal to Noise ratio (unitless) figure of 1.171\n> (representing 4.5 dB eb/no with a data rate of 1 Gbps and a bandwidth\n> of 2.4x109 Hz)\n> \n> Question : is 1 gbps not 1x109 bps ?\n> \n> Question : if both antennas are 3m parabolic (both are the same type)\n> with 56.4 dBi boresight gain, what would you think the furthest\n> distance the link can perform with SNR of 1.171. I have actually used\n> a padding of 3 dB Eb/No in my link budget, so am not worried about any\n> further signal loss at first (ok, I should be ..) For the exercise, I\n> am choosing a 10 Watt estimated output on an arbitrary basis.\n> \n> So:\n> \n> P_t = 10W\n> \n> G_t = 56.4 dBi = G_r , can we assume the same gain for TX and RX on a\n> parabolic dish ?\n> \n> T = 3000K at receiver\n> \n> SNR = 1.171 required\n> \n> f=32.2 GHz\n> \n> B = 2.4E9 Hz, (bpsk, ldpc code 0.5)\n> \n> DR = 1E9 bps\n> \n> So, I am puzzled why this link budget says the range with these\n> parameters is equal to 4.644 x 109 Km -- that seems to be a long\n> distance ! What am I not able to conceptualize.\n> \n> \n> BTW, I know if I send this out, the answer will come to me soon\n> thereafter, but for education, I would like to know where the problem\n> in my understanding lies !\n> \n> \n> Samudra N3RDX\n> \n> \n> ------------------------------\n\n",
    "attachments": []
}