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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/GFNTL4OG2NJBRZDKIQOLCAABPZQ7USMZ/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "001d01d0969a$270a97c0$751fc740$@net",
    "message_id_hash": "GFNTL4OG2NJBRZDKIQOLCAABPZQ7USMZ",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/GFNTL4OG2NJBRZDKIQOLCAABPZQ7USMZ/?format=api",
    "sender": {
        "address": "tjschuessler (a) verizon.net",
        "mailman_id": "e00b615eeb1940c790a22f139add6462",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/e00b615eeb1940c790a22f139add6462/emails/?format=api"
    },
    "sender_name": "Tom Schuessler",
    "subject": "Re: [amsat-bb] PSAT and Bricsat FM PSK on same frequencies",
    "date": "2015-05-25T03:23:21Z",
    "parent": null,
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Bob,\n\nYour explanation to my questions make much more sense now that I worked\nanother pass of the satellites.  Today the two were sufficiently separated\nthat I could see one lagging behind and thus higher up in frequency because\nof Doppler shift.  Your explanation on why the same frequencies for the two\nbirds is quite nice.  Also the frequency offset difference for the PSK\nbeacons as well as the different IDs work as well.\n\nBricsat was quite a bit weaker but that was probably because I was trying to\ntrack PSAT with my Arrow on a tripod.  It was also a couple of Khz higher\nup.  I also saw the difference in the two beacons so now I know how to tell\nwhich from which.\n\nI did try transmitting PSK31 USB on 28.120 + 1Khz or so and listening\nthrough HDSDR on 435.350.  I heard faint signals of other PSK signals but\nbelieve they were just some other terrestrial QSOs and not directed through\nthe satellite.  They were slipping down the DIgipan waterfall as they would\nbe without correction.  I was not doing correction either on 28Mhz but I was\nhoping, even on playback of the HDSDR I/Q recording, to find me but I never\ndid.  Going to try a different software configuration next weekend to try\nand hear myself live.\n\nThe best time to test PSK through these satellite transponders will be\novernight passes when possible so as to avoid terrestrial stations from\ncalling other terrestrials and confusing things.  Will have to wait for\ntimes to shift for that.\n\n73, Tom, N5HYP\n\n____________________________\n\nMessage: 11\nDate: Sun, 24 May 2015 10:56:55 -0400\nFrom: Robert Bruninga <[email protected]>\nTo: [email protected]\nSubject: Re: [amsat-bb] PSAT and Bricsat FM PSK on same frequencies\nMessage-ID: <[email protected]>\nContent-Type: text/plain; charset=UTF-8\n\n> ... how will this work with two FM satellites on the same frequency?\n\nThe idea is to serve users no matter which spacecraft is in view.  And to\nnot have the users have to always change frequencies and track different\nobjects.  Imagine a camper in the field.  Just point your beam towards AOS\ngenerally and set +5 KHz tuing and when a satellite comes into view, you can\nuse it.\n\nMany things separate them:\n1) Distance\n2) Time\n3) Doppler\n4) Users antenna beamwidth\n\nWhen they are 5 minutes apart, the beam headings will be over 90 degrees\napart (10 to 15 dB separation), the Doppler will be typically 10  KHz\n(10-15 dB separation) for a total of 20-30  dB or more to prevent capture\neffect.\n\nSince an orbit is 95 minutes long, and the satellites will drift, then 95%\nof the time, this condition of at least 5 minute separation, will be met.\n\nPSAT PSK (W3ADO-5) was built over 3 years ago and is hardwired to power up\nby default (maximum chance it will work despite spacecraft packet link or\nother failures)\n\nBRIC PSK (W3ADO-6) was built just last year and has independent control by\nBrno designers (can be off while sats are adjacent)  It also powers up by\ndefault (again, for maximum availability in case of bus failure).\n\nSo I think the choice pretty much meets the goals of maximum availability to\nusers and as independent of spacecraft failures as we could make them.\n\nHope that Helps.\nBob, WB4aPR\n\n\n\n",
    "attachments": []
}