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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/BXGWSCBTTXARAVNZSZQYPN3CEQJKKFLT/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "BXGWSCBTTXARAVNZSZQYPN3CEQJKKFLT",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/UYGE6XKIPFCHUJYONOY4EQ7FROFK3MSX/?format=api",
    "sender": {
        "address": "bob (a) evoria.net",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Bob Stewart",
    "subject": "[amsat-bb] Re: AO-27 (TOPR?) SCHEDULE",
    "date": "2007-09-13T18:06:21Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/UYGE6XKIPFCHUJYONOY4EQ7FROFK3MSX/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "The AO-27 transponder is generally on while it's over the US.  Mostly\nI see it go into its data mode and then shut down at more-or-less the \nCanadian border on ascending passes.  I can't think of a pass where it \nwas off since I've been using it - about 2 1/2 months.  I have no idea \nwhether this changes during other times of the year.\n\nBob - AE6RV\n\n--- Eric Fort <[email protected]> wrote:\n\n> Are there any pieces of software or web tools that will allow the input of\n> qth and give pass data for ao-27 that shows transponder on passes only?  I'm\n> looking for a simple way to tell weather or not the pass (or portion\n> thereof) is workable.\n> \n> Eric\n> KG6KQT\n> \n> On 9/13/07, Patrick STODDARD <[email protected]> wrote:\n> >\n> > Hi Eric!\n> >\n> > > I just reviewed the pass prodictions for ao-27 on the amsat website.  I\n> > then\n> > > followed the link to ao27.org.  now I'm a bit confused.  On ao27.orgthere\n> > > is listed a TOPR schedule with little explanation of what TOPR is.  It\n> > > appears however that this causes the satellite to turn on and off it's\n> > > transponder at various times.  If this is the case how does one\n> > determine\n> > >  usable passes?  A satellite overhead without a functional transponder\n> > is\n> > > about as useless as mammaries on a bull! It seems it could be a source\n> > of\n> > > significant frustration if trying to work a pass only to find out the\n> > sat\n> > > had switched itself off!\n> >\n> > First of all, AO-27 is an old satellite - about 14 years old.  Its\n> > batteries, although\n> > functional, aren't what they used to be.  This satellite originally\n> > had a non-ham\n> > use along with its use as a ham FM cross-band repeater, but now it is\n> > pretty much\n> > just used by the hams.  To keep from ruining what's left of the\n> > batteries, the control\n> > operators of that satellite (most of the time, just Michael N3UC) have\n> > found a way\n> > to keep it functional through this summer despite its age.  Especially\n> > when\n> > considering that summertime is generally the \"eclipse season\", when\n> > the satellite\n> > is in darkness for a significant part of each orbit, not able to get\n> > its batteries\n> > fully charged to support full-time operations.\n> >\n> > Last year, the satellite was working through the winter into\n> > springtime.  In early\n> > May 2006, it started to operate intermittently, and then stopped\n> > working.  At\n> > that time, it was on as an FM repeater for 6 minutes per ascending pass\n> > (from\n> > South to North) over the Northern Hemisphere along with telemetry\n> > transmissions\n> > before and after the repeater time plus an additional telemetry\n> > transmission on\n> > descending passes (passes going from North to South).  It stayed\n> > silent until early this\n> > year, and - after many weeks of testing and tweaking - and now it has been\n> > on\n> > for 7 minutes per daytime pass over the Northern Hemisphere.\n> >\n> > The TOPR (previously TEPR) scheduling determines when the satellite is on\n> > and\n> > in what configuration - analog repeater or digital telemtry\n> > transmission, and the\n> > power level.  Most of the time the power level is \"Med\" (around\n> > 500mW).  For the\n> > past couple of years, the FM repeater would come on after 20 seconds of\n> > data\n> > and then there would be another minute or so of data after the repeater\n> > switches\n> > off.  Currently, the repeater switches on for 7 minutes once the\n> > satellite reaches\n> > approximately 28-29 degrees North latitude on any ascending pass (moving\n> > from South to North) where the satellite is in daylight.  The schedule\n> > is uploaded\n> > to the satellite, but the satellite's onboard clock runs a little fast.\n> >\n> > Officially, you can see AO-27's schedule for the upcoming 24 hours on this\n> > page:\n> >\n> > http://www.ao27.org/AO27/listing.shtml\n> >\n> > My observations show that the schedule listed on this page is about 5-6\n> > minutes later than the actual times.  There is a program you can download\n> > and run on your computer (Java-based) that will do the same thing.  It can\n> > be found at:\n> >\n> > http://www.cs.rit.edu/~cjh9783/programs/satsched.php\n> >\n> > If you don't have a program to unpack RAR archives, I can e-mail the\n> > AO-27 program to you in a ZIP archive.\n> >\n> > You can tell when the schedule was made from looking on the\n> > http://www.ao27.org/ homepage.  Look for the \"TOPR Epoch\" near the\n> > middle of the page.  The last time the schedule was updated was in\n> > late June, so you can determine the approximate difference between\n> > the satellite's onboard clock and the \"real\" time when looking at the\n> > schedule.\n> >\n> > For my location, I have two possible AO-27 passes this afternoon according\n> > to the pass-prediction utility on the AMSAT web site: 2137-2152 UTC, and\n> > 2317-2331 UTC.  The AO-27 Satellite Schedule program shows that, for those\n> > passes, the repeater should be on for 7 minutes starting at 21:42:51 and\n> > 23:23:40 UTC (before accounting for the satellite's clock discrepancy -\n> > about\n> > 40-60 seconds before these times).\n> >\n> > Is it frustrating that a satellite like this is only available for\n> > only portions of\n> > some passes?  Sure.  This has been the way AO-27 has operated for\n> > many years, and despite those limitations there are usually good crowds\n> > working the passes that cover most of North America.  In my satellite log,\n> > I\n> > have made almost 25% of my 2800+ satellite contacts on AO-27, despite\n> > its limitations and the fact it had been off for several months in 2006\n> > and\n> > into the start of 2007.\n> >\n> > Good luck and 73!\n> >\n> >\n> >\n> > Patrick WD9EWK/VA7EWK - Phoenix AZ\n> > http://www.wd9ewk.net/\n> >\n> _______________________________________________\n> Sent via [email protected]. Opinions expressed are those of the author.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n> \n\n",
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}