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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/WC27DI5SYNWIMVBFYJ656BKX62EZGEDZ/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "133E3E402B3048A1A410F160A271C61D@parents",
    "message_id_hash": "WC27DI5SYNWIMVBFYJ656BKX62EZGEDZ",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/HXAX3GIG5EQJECYZPH4OMTXXYAD7HC7L/?format=api",
    "sender": {
        "address": "ka3hsw (a) att.net",
        "mailman_id": "afface7d7e8049fda539552165bdde78",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/afface7d7e8049fda539552165bdde78/emails/?format=api"
    },
    "sender_name": "George Henry",
    "subject": "Re: [amsat-bb] Note ref. doppler w/ UHF iGate listener for ISS\tPacket",
    "date": "2016-11-14T05:45:14Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/HXAX3GIG5EQJECYZPH4OMTXXYAD7HC7L/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "If your receiver is equipped with AFC, like the Icom IC-910, it will correct \nfor doppler without the need to do it in software...\n\n\nGeorge, KA3HSW\n\n\n----- Original Message ----- \nFrom: \"Scott\" <[email protected]>\nTo: <[email protected]>\nSent: Sunday, November 13, 2016 1:48 PM\nSubject: [amsat-bb] Note ref. doppler w/ UHF iGate listener for ISS Packet\n\n\n> Hello everyone.\n>\n> For anyone who has an interest in using the digipeater on the ISS now that\n> it has switched to 70cm, I wanted to pass along some non-scientific\n> findings.\n>\n> Of course it's great to see your packets digipeated from the ISS but part\n> of the fun also is showing up on the ariss.net website which lists\n> digipeated packets that were received by a ground station setup as an\n> \"iGate\" to forward that traffic over the internet (resulting in a listing\n> on the ariss.net website).\n>\n> It is my understanding that a couple of factors are contributing to a\n> reduction in the number of digipeated packets successfully making it to \n> the\n> ariss.net site.\n>\n> For one, there are less iGates able to receive on 70cm.  That issue can be\n> resolved over time as people naturally add the ability to listen on 70cm\n> with an iGate app.\n>\n> But another issue that several folks have pointed out is that with the \n> more\n> substantial doppler shift at 70cm, a receiver set to a single frequency\n> will miss much of the traffic sent back down from the ISS.\n>\n> I have never run an iGate and wasn't completely sure what was involved, \n> but\n> with a number of SDR-equipped Raspberry Pi's around here I wanted to put\n> one more set of ears out there for UHF packet.\n>\n> I'm sure there are any number of ways to setup a Pi as an iGate; I used \n> the\n> instructions at:\n> https://github.com/wb2osz/direwolf/blob/master/doc/Raspberry-Pi-SDR-IGate.pdf\n>\n> But how to setup a Pi is not why I wanted to post this.  Of course I\n> initially setup my Pi-iGate to listen on the published frequency of\n> 437.550.  However, I received very few packets from the ISS.\n>\n> It crossed my mind that, at the point of closest approach, the doppler\n> frequency is changing quite rapidly.  So, I thought that I might improve \n> my\n> count of iGated packets if I listened on a frequency that would be viable\n> for a longer period of time.  Using (WD9EWK) Patrick's doppler adjustment\n> guide as a reference, I chose to change my listener to 437.555.\n>\n> Again, this is not scientific, but I am now receiving more packets on the\n> Pi-iGate than I was before.  Only time will tell if this continues.  Of\n> course the better solution would be to program the Pi to adjust for \n> doppler\n> throughout the entire pass and there IS code online to provide that\n> compensation.  However, I have not been able to get that working.\n>\n> If anyone is interested, here is the script that I run to activate the\n> iGate listener on my Pi... it runs in the background so that I can log off\n> from the Pi and just leave it running stand-alone.\n>\n> -----------------------------------------------------\n> #!/bin/bash\n> nohup rtl_fm -f 437.555M - | direwolf -l /home/pi/iss-uhf-log/ -c\n> /home/pi/sdr.conf -r 24000 -D 1 - > /dev/null 2>&1 &\n> #\n> -----------------------------------------------------\n>\n> Hope someone finds this informative and at least one of you might be\n> prompted to add a 70cm iGate to your shack!\n>\n> 73,\n>\n> -Scott,  K4KDR\n> Montpelier, VA  USA\n> _______________________________________________\n> Sent via [email protected]. AMSAT-NA makes this open forum available\n> to all interested persons worldwide without requiring membership. Opinions \n> expressed\n> are solely those of the author, and do not reflect the official views of \n> AMSAT-NA.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb \n\n\n---\nThis email has been checked for viruses by Avast antivirus software.\nhttps://www.avast.com/antivirus\n\n",
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}