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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/2RC7WK76VWD4GRBNWMCK3YJNUAQPOH2X/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "2RC7WK76VWD4GRBNWMCK3YJNUAQPOH2X",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/UPK4RTUGRHTRVDPDYXKITZDIFRCLMXOK/?format=api",
    "sender": {
        "address": "ko6th_greg (a) hotmail.com",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Greg D.",
    "subject": "[amsat-bb] Re: Galileo interference on L band",
    "date": "2006-09-23T20:11:20Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/4PWNJNZ6GLINHPUSG45MJYF6UTP3KGSC/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "So, interference in the \"safety for life\" band is of interest to the \ngovernment, and lots of testing, backups, and certification will be required \nto use it.  Interference in the \"commercial\" band is of interest to \nGalileo's bottom line ($$), and they will be motivated ($$, again) to invest \nthe least for the best payback.  My worry is that it may appear cheaper to \nthem to try to ban all other uses of those frequencies, than to invest in \nthe engineering design and end-user hardware components to prevent that \nservice from going down.  Loss of life due to interference cannot be \ntolerated, of course, but to see what motivates action, follow the money.\n\nGreg  KO6TH\n\n\n----Original Message Follows----\nFrom: Bruce Rahn <[email protected]>\nReply-To: [email protected]\nTo: \"John B. Stephensen\" <[email protected]>\nCC: amsat bb <[email protected]>\nSubject: [amsat-bb] Re: Galileo interference on L band\nDate: Thu, 21 Sep 2006 14:28:21 -0400\n\nJohn B. Stephensen wrote:\n > High-accuracy receivers use multiple downlink frequencies to compensate \nfor\n > errors, such as those induced by the ionosphere. There are probably 3\n > downlink frequencies in case 1 fails.\n >\n > 73,\n >\n > John\n > KD6OZH\n >\n > ----- Original Message -----\n > From: <[email protected]>\n > To: \"amsat bb\" <[email protected]>\n > Sent: Thursday, September 21, 2006 16:54 UTC\n > Subject: [amsat-bb] Re: Galileo interference on L band\n >\n >\n >\n >> I understand this argument. BUT what i do not understand is the idea\n >> that an airliner would only be receiving one of the three bands that\n >> Galileo is saying that it intends to use for GPS. The L band is in\n >> just one of those three bands that the airplane would be receiving.\n >> Would the system not require the receiver to take data from the best\n >> signal? Could we not ask the FAA to require any airborne receiver\n >> that it certify must receive all three bands and switch bands if it\n >> receives any interference?\n >>\n >> As a practical matter G GPS is not now in orbit, it would take years\n >> before it could be funded, launched and be operational. Then it would\n >> take the FAA probably another 10 years before they would certify it\n >> for use.  I see 10-15-20 years before Galileo might be a problem to \nhams.\n >>\n >> Why not fly Eagle with a backup L/S linear and use C/X for the\n >> digital transponder?\n\nThis debate grows more interesting with time.\n\nCurrent publicly available Galileo documentation indicates that \"Safety\nof Life\" services will be provided on  E5a/E5b (1164 to 1215 MHz)\ndownlink and the E2/L1/E1 (1559 to 1591 MHz)  downlink.  The E6 (1260 to\n1300 MHz) downlink is designated for 'commercial services' and not the\naviation.  Thus, I am VERY curious why the interference to aircraft\nnavigation receivers is constantly brought up in this discussion as it\nappears a non-player.\n\nFor all but the most precise needs, dual frequency capabilities will\neliminate the 1st order ionospheric errors leaving only the 2nd and 3rd\norder terms which are on the centimeter level.  Thus I don't see the\nneed for aircraft navigation systems to employ 'tri-frequency' receivers.\n\nWhat am I missing here?\n\n\n--\nBruce Rahn\n\nWisdom has two parts:\n1.  having a lot to say; and\n2.  not saying it!\n\n_______________________________________________\nSent via [email protected]. Opinions expressed are those of the author.\nNot an AMSAT-NA member? Join now to support the amateur satellite program!\nSubscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n\n\n",
    "attachments": []
}