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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/ZS5T5J44AGURLQRBXYU5G4TK52YQTJH5/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "20120504102900.31XLA.62733.root@viefep11",
    "message_id_hash": "ZS5T5J44AGURLQRBXYU5G4TK52YQTJH5",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/ZS5T5J44AGURLQRBXYU5G4TK52YQTJH5/",
    "sender": {
        "address": "pa3guo (a) upcmail.nl",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "PA3GUO",
    "subject": "[amsat-bb] How to measure the performance of my satellite station ?",
    "date": "2012-05-04T08:29:00Z",
    "parent": null,
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Since I had been in-active for quite a number of weeks, of course I first wanted \nto check if my (70cm) satellite station was still functional. \n \nThe first step I always take is listening to the stable beacon of HO-68, CW @435.790MHz. \nMy goal is to have the antenna tracked automatically, and frequency PC controlled by HRD. \nWhen the result is that I hear the beacon, no doppler shift, I know this first step is taken \n(means hardware and software incl kepler sets seem to work). Now what next ? \n \nSignal strength of that CW beacon is one way to measure my station, another way \nis looking at RAX-2, which transmits at 437.345 MHz (9k6 FM packets, KISS mode). \nRAX sends these days each 10 seconds a short burst of data. Using the free \ndecoding SW from the RAX team you can:\na) analyze the satellite data yourself \nb) help the scientific experiments of the university by forwarding the telemetry \nc) test your own station ! \n \nhttp://rax.engin.umich.edu/?page_id=301 \n \nAn example is this mornings pass, which had a max elevation of 46 degrees. With \nmy 16 elements DK7ZB (http://pa3guo.com/ant_jun_2011.jpg) my station could \nhear the satellite starting at 2 degrees elevation, and decode at around 8 degrees. \nSee the table below (decode timestamps from the decoding software) \n \n4 May 2012 07:51:38 GMT (6.2 degrees elevation) \n4 May 2012 07:51:49 GMT \n4 May 2012 07:52:01 GMT \n4 May 2012 07:52:09 GMT \n4 May 2012 07:52:19 GMT \n4 May 2012 07:52:29 GMT \n4 May 2012 07:52:39 GMT \n4 May 2012 07:52:50 GMT \n4 May 2012 07:53:02 GMT \n4 May 2012 07:53:10 GMT \n4 May 2012 07:53:20 GMT \n4 May 2012 07:53:30 GMT \n4 May 2012 07:53:41 GMT \n4 May 2012 07:53:51 GMT \n4 May 2012 07:54:01 GMT \n4 May 2012 07:54:11 GMT \n4 May 2012 07:54:21 GMT \n4 May 2012 07:54:32 GMT \n4 May 2012 07:54:42 GMT \n4 May 2012 07:54:52 GMT \n4 May 2012 07:55:02 GMT \n4 May 2012 07:55:12 GMT \n4 May 2012 07:55:22 GMT \n4 May 2012 07:55:33 GMT \n4 May 2012 07:55:43 GMT \n4 May 2012 07:55:53 GMT \n4 May 2012 07:56:03 GMT \n4 May 2012 07:56:13 GMT \n4 May 2012 07:56:24 GMT \n4 May 2012 07:56:34 GMT \n4 May 2012 07:56:44 GMT \n4 May 2012 07:56:54 GMT \n4 May 2012 07:57:05 GMT \n4 May 2012 07:57:15 GMT \n4 May 2012 07:57:25 GMT \n4 May 2012 07:57:35 GMT \n4 May 2012 07:57:45 GMT \n4 May 2012 07:57:55 GMT \n4 May 2012 07:58:06 GMT \n4 May 2012 07:58:16 GMT \n4 May 2012 07:58:26 GMT \n4 May 2012 07:58:36 GMT \n4 May 2012 07:58:46 GMT (11 degrees) \n... \n4 May 2012 07:59:48 GMT (5 degrees) \n \nSo at the end my station stopped decoding at 11 degrees elevation, it picked up a final beacon at 5 degrees. \nWe could define a kind of 'Ground Station Effectiveness' as number of packets decoded (not heared!) between \na certain elevation threshold (eg 10 degrees). When no packet would be missed my station would rate now \nfor 100% (at 10 degrees). \nOr more scientifically: the GS effectiveness of PA3GUO's station is 100% (@10 degrees elevation)\n \nAll kinds of items can bring this number down from 100% to lets say 80%: \n- hard mechanical stop of the rotor, forcing a full 360 degrees turn during a pass\n- interference of other signals/satellite during a pass (at the same frequency) \n- tumbling of the satellite (antenne pointing to wrong direction)\n- polarization changes (rotation of the satellite) \n \nWell, the above shows that my 1x16 elements (horizontal pol) antenna works fine to support missions like RAX. \nNo need for circular antenna (admitted: other satellite give different results for circular (both better and worse) \n \nJust sharing some thoughts, looking forward to your feedback / reflections !\n \nHenk, PA3GUO \n\n",
    "attachments": []
}