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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/DPGU3K4VKZSNBHOUQBUYEFDUWJGXKYWY/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "DPGU3K4VKZSNBHOUQBUYEFDUWJGXKYWY",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/DPGU3K4VKZSNBHOUQBUYEFDUWJGXKYWY/?format=api",
    "sender": {
        "address": "saguaroastro (a) cox.net",
        "mailman_id": "a4a1e7d14c254c03bd1ba487c7a01f6d",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/a4a1e7d14c254c03bd1ba487c7a01f6d/emails/?format=api"
    },
    "sender_name": "Rick Tejera",
    "subject": "Re: [amsat-bb] Receiving PSAT PSK31 FM downlink",
    "date": "2015-05-22T03:48:04Z",
    "parent": null,
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "\n    \n\n\n\n\nSent from my Verizon Wireless 4G LTE smartphone\n\n-------- Original message --------\nFrom: Robert Bruninga <[email protected]> \nDate: 05/21/2015  16:19  (GMT-07:00) \nTo: [email protected] \nSubject: [amsat-bb] Receiving PSAT PSK31 FM downlink \n\nReceiving the PSAT (and BRICsat) 435.350 MHz FM downlink is as simple as\nplacing  your PSK31 laptop microphone next to the speaker on your FM\nsatellite UHF receiver and just watching the waterfall.\n\nWhat you see is exactly what everyone else sees (its FM).  There is no\nDoppler added to the tones due to your station's position relative to the\nsatellite.  But you DO have to retune your FM radio at least 3 times\nduring the pass (+5 KHz, 0, -5 KHz) to stay in the FM passband.\n\nUser uplinks, however, will shift in the waterfall according to each\nuser's position relative to the satellite.  The shift can be as low as 1\nHz per second to as high as 6 Hz per second.  This is because the uplink\nis on 10 meters where the Doppler rate is only 1/15th of what it would be\non UHF.\n\nThe TELEMETRY channel at 315 Hz (PSAT) or 375 Hz (BRICsat) is FIXED with\nno Doppler since it is generated onboard into the FM downlink\n\nWHAT TO DO:\n\n1) We will need PSK31 authors to open the PSK31 frequency tracking to\naccommodate more than 1 Hz per second Doppler tracking.  Current\nimplementations can do 1 Hz/s but completely fail at 3 Hz/s.  2 Hz/s might\nwork a little...\n\n2) Until then, ANY uplink user that is in line with a direct overhead pass\nwill have minimum Doppler at the start and end of his pass (1 Hz/sec) when\nthe satellite is going right at him and directly away from him.  (Though\nit will be MAX (6Hz/sec) when it passes over his station).\n\n3) Just turn on MULTI CHANNEL window and let the PSK31 decode everyone.\nThe ones with the least Doppler at any instant may be decoded for a while!\n\nUSERS can transmit later when BRNO University says it has completed its\ntests.  Brno provided the transponders for use in the PSAT and BRICsat\nsatellites.\n\nSo start preparing your station to TX PSK31 on 10 meters SSB and to\nreceive the audio from an FM UHF rig on 435.350 +/- 5 KHz steps of\nDoppler.\n\nDOWNLINK Limitations:  The UHF downlink signal is only 300 mW and so a UHF\nbeam is needed on the downlink.\n\nUPLINK RESTRICTIONS:  *NOTHING MORE THAN* a Vertical 1/4 wave or Dipole is\nauthorized on the 10m uplink  and no more than 25 Watts (for now).\nRemember a 1/4 wave vertical is the ideal antenna because it maximizes the\nsignal at lower angles and tapers the signal as the satellite gets closer.\nThis keeps  user uplinks about the same during a pass.  Strong stations\njust drive down the AGC and ruin it for everyone.\n\nUse minimum power!!  Remember, this is crossband FULL DUPLEX so  you can\nsee yourself in the downlink just like everyone else can see you.  Act\naccordingly.  And of course DO NOT TRANSMIT if you cannot see the\nwaterfall  ... Duh!\n\nEnjoy!\n\nBob, WB4APR\n_______________________________________________\nSent via [email protected]. AMSAT-NA makes this open forum available\nto all interested persons worldwide without requiring membership. Opinions expressed\nare solely those of the author, and do not reflect the official views of AMSAT-NA.\nNot an AMSAT-NA member? Join now to support the amateur satellite program!\nSubscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb\n",
    "attachments": []
}