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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/YKT6CE2RZ6QCUNUXUADECFOXPDDR5TF5/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "YKT6CE2RZ6QCUNUXUADECFOXPDDR5TF5",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/YKT6CE2RZ6QCUNUXUADECFOXPDDR5TF5/",
    "sender": {
        "address": "w.j.ubbels (a) lr.tudelft.nl",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "W.J. Ubbels",
    "subject": "[amsat-bb]   Re: CubeSat launch 27Mar07 6:46:35UT",
    "date": "2007-03-25T19:09:40Z",
    "parent": null,
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi all,\n\nwith the discussion about the upcoming CubeSat launch in mind, and since \nwe have not been able to update our website regularly just a couple of \nwords from the Delfi-C3 office:) We are currently very busy integrating \nthe spacecraft. Although it's a 3-unit CubeSat, it's still very, very \nsmall... so that gives some headaches sometimes:)\n\nDelfi-C3 carries two redundant (primary and backup), and almost similar \nradio transceivers, connected to the antenna system by a hybrid combiner \nwhich also takes care of generating the correct phase relationship \nbetween the antennas. Both transceivers consist of a UHF frontend, a \ncommand receiver, linear IF, telemetry generator and the final stages \ncapable of 400mW RF power. Each transceiver is housed on a single 96 x \n90mm board. Our tight power budget allows only one transmitter to be \nactive at all times.\nDelfi-C3 contains no batteries, one of the reasons being the fact that \nit's primary mission is to perform a solar cell and sun sensor \nexperiment which depend on the presence of sunlight. Therefore, the \nspacecraft is only active when in sunlight. Of course, since there's no \nsuch thing as a free lunch, this has made the design complicated on an \nother level, especially software-wise. (proper boot-up sequences etc.)\n\nThe first three months of the mission are what we call the \"science\" \nmission, in which the spacecraft will be transmitting 1200 bit/s AX.25 \ntelemetry on either the primary or backup VHF downlink frequency, \nfrequency information can be found on our website http://www.delfic3.nl\nTelemetry is contained in UI frames, with roughly one frame every \nsecond. All detailed information regarding telemetry will be announced \non the website as well.\nModulation is Raised Cosine (in time) BPSK, more or less similar to that \nof the Microsats. Therefore, owners of a PSK TNC such as the NB-96/PSK-1 \ncombo can use them with the software (written in JAVA) that we will \nsupply (will be made available via our website). This software package \nconnects to the TNC in KISS mode, and allows you to display telemetry in \nreal time, and upload it to our central server in Delft. Since PSK TNC's \nare not that common anymore in today's shacks, and PC's are, we are \ndeveloping a soundcard application in JAVA that can be used with the \ntelemetry decoding software. An other option is to use the popular mixw \nprogram, which can demodulate BPSK and emulate a KISS TNC.\n\nAfter three months, the linear transponder will be activated, with a \n40kHz bandwidth. In transponder mode, a CW beacon will be active instead \nof BPSK telemetry.  This CW beacon is actually transmitted as double \nsideband, with two carriers spaced 1200Hz apart. It will transmit a \nmessage saying \"hi hi de delfi-c3 delfi-c3\". Beacon power is set at 10dB \nbelow transponder PEP, users are requested to limit uplink power to the \nnecessary minimum to maintain a proper downlink, while not driving the \nAGC excessively high. Since Delfi-C3 can indeed be considered a \n\"hardsat\", with only 400mW of downlink power, it is wise to pay \nattention to a good receive system. The transponder IF is very basic, \nconsisting of ceramic filter to set the bandwidth, an amplifier chain on \n10.7MHz and a fast-attack / slow-decay AGC. You can listen to an audio \nclip of the first transponder test QSO (in Dutch...) between PA3WEG (who \ndesigned the local oscillators) and PE4WJ at \nhttp://www.delfic3.nl/wavs/Delfi-C3_transponder_link_with_QRM.mp3\n(Mind you, there is some QRM in the file that might sound a bit like \nLeila, but this is pure coincidence)\n\nWith regard to the orbit, TLE's will be anounced on the website \n(www.delfic3.nl) once they are available, for now I can give the \nfollowing preliminary parameters:\n-altitude: 630km circular\n-inclination: 97.91 degrees\n-sun-synchronous\n-LTAN: 10:30\n\nOk, back to satellite building now:)\n\nBest 73,\n\nWouter Jan Ubbels PE4WJ\n\n-- \nW.J. Ubbels MSc.\nDelfi-C3 project manager electronic systems and communications\nFaculty of Aerospace Engineering\nDelft University of Technology\nwww.delfic3.nl\nPE4WJ\n\n",
    "attachments": []
}