Email Detail

HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/OW6Q2EAX7DYRM6OPFIQHC2Y5YXM7URNA/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "OW6Q2EAX7DYRM6OPFIQHC2Y5YXM7URNA",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/5HCWDGY7NTFKXMOTF2O7KEJMGKDL6VW4/",
    "sender": {
        "address": "oe6pse (a) wirklich.priv.at",
        "mailman_id": "fa4fb017902d44de886b2b4476096eb5",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/fa4fb017902d44de886b2b4476096eb5/emails/"
    },
    "sender_name": "Patrick Strasser OE6PSE",
    "subject": "[amsat-bb] Re: Decoding wideband recordings",
    "date": "2011-08-18T15:15:55Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/5HCWDGY7NTFKXMOTF2O7KEJMGKDL6VW4/",
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/ERTHDWTXUGJFHBSMWHIBDBLJR427CYU7/"
    ],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Am 2011-08-10 00:54, schrieb Phil Karn:\n> It's been suggested that I modify my ARISSat-1 BPSK-1000 telemetry\n> demodulator/decoder to accept wideband quadrature (I & Q) recordings\n> like those produced by most of the software defined radios out there.\n> \n> This is fundamentally not that hard, but first I need some information.\n> \n> How many people could actually use this?\n\nI guess all people that use SDRs in the style of FCD, like SDR Widget,\nor generally all DDC receivers that work with soundcard interfaces.\n\n> What is the format of the\n> recorded files? Is there a standard, or does each make of SDR produce\n> its own?\n\nOften the I and Q channel are recorded via Left and Right of a sound\ninterface, either built-in in the computer or via USB. FCD for example\nis not more than a very powerful DDC chain, an USB audio device with\n96kHz bandwidth and a USB HID interface to control all the settings,\nlike filters and gains. So for a recording you'd probaly end up in\nwhatever your recoding program produces, likely WAV, but any format with\n16bit and 2 channels would do.\n\nFor decoding please be aware that I/Q via sound interfaces has a weak\nspot at the centre frequency. The interfaces all have a high pass\ncharacteristic below like 30Hz, which means the resulting spectrum has a\nnotch in the middle. You usually would not like to exactly tune the\ncenter frequency to the frequency of your interest, but a little below\nor above. You can see that notch for example at\n\nhttp://www.oz9aec.net/index.php/funcube-dongle/423-funcube-dongle-on-the-air-tests-at-oz7sat\nWith all oscillators being not perfect this can probably be ignored, as\nyou wouldn't end up at the center frequency anyway.\n\nFor converting audio files I can recommend sox\n  http://sox.sourceforge.net\nwhich is quite common in Linux distributions, but as cross platform tool\nalso available for Windows and Mac OS X. It's also available as library.\n\nWhat I wonder is how good BPSK1000 survives speech encoders, like MP3.\nIs there any experience already?\n\n73\n\nPatrick\n\n\n\n-- \nEngineers motto:   cheap, good, fast: choose any two\nQTH: JN77rb                       http://sat.mur.at/\nPatrick Strasser OE6PSE <oe6pse at wirklich priv at>\n",
    "attachments": []
}