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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/RCU6I7JYOWV3VKO2WDNI227JFMN5RZNN/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "74947E53F52B401E88A6DDDF6DB21410@athlon",
    "message_id_hash": "RCU6I7JYOWV3VKO2WDNI227JFMN5RZNN",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/B5K3JKQZYHSDXJSNFPTUXBSAGVUNBMCS/?format=api",
    "sender": {
        "address": "ve4yz (a) mts.net",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Alan",
    "subject": "[amsat-bb] Re: Help for Humber College Students with ISS Contact",
    "date": "2008-11-27T02:29:52Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/PQYEL7AJEAH4HHNEKBBK7MLD7ISNTJWH/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": " \nSorry for the spam but I neglected to include the URL to a great open source\napplication ENAMIN\n\nhttp://www.enzim.hu/~szia/emanim/emanim.htm used to create these graphic\nsimulations of polarization\n\nYou don't have to download and run it... Several samples are included on the\nsite such as\n\nhttp://www.enzim.hu/~szia/cddemo/edemo0.htm\n\n\n... Alan\n\n\n-----Original Message-----\nFrom: Alan [mailto:[email protected]] \nSent: November 26, 2008 8:16 PM\nTo: 'Roger Kolakowski'; '[email protected]'; '[email protected]';\n'[email protected]'; '[email protected]'\nSubject: RE: [amsat-bb] Re: Help for Humber College Students with ISS\nContact\n\nWith all due respect to describing LHCP and RHCP which gives me a brain\ncrap... Here is a visualization of polarization.\n\nhttp://sv1bsx.50webs.com/antenna-pol/polarization.html\n\n\n... Alan\n\n\n-----Original Message-----\nFrom: [email protected] [mailto:[email protected]] On\nBehalf Of Roger Kolakowski\nSent: November 26, 2008 5:38 PM\nTo: [email protected]; [email protected]; [email protected];\[email protected]\nSubject: [amsat-bb] Re: Help for Humber College Students with ISS Contact\n\nNice explanation...Thank you!\n\nRoger\nWA1KAT\n\n----- Original Message -----\nFrom: <[email protected]>\nTo: <[email protected]>; <[email protected]>; <[email protected]>\nSent: Wednesday, November 26, 2008 11:04 AM\nSubject: [amsat-bb] Re: Help for Humber College Students with ISS Contact\n\n\n> Hi all,\n>\n> Let me clear up a little bit of what ARISS wants for a school ground \n> station.  What you do for your own home contact is your business but \n> here\nis what we\n> want for an ARISS school contact:\n>\n> 1.  We require two complete radio stations, each one 75 watt  class or\nbetter\n> (we actually prefer over 100).  RF amps are OK.  The  radios should \n> have\nthe\n> ability to go in frequency steps smaller than 5kHz so  that the \n> Doppler\nshift\n> can be corrected (at 2 meters it goes about +/-3.5  kHz).\n> 2.  The primary radio is to have a circular polarized beam with \n> azimuth\nand\n> elevation control rotors.  We prefer computer control of the  rotors.\n> 3.  The backup radio is to have a vertical and/or eggbeater style\nantennas.\n>\n> Now for a short explanation of why for each:\n>\n> 1.  The need for two complete radios is so that if one radio fails for\nany\n> reason, the school contact can carry on (it is recommended each radio \n> be\non\n> its own 120VAC circuit and UPS if possible).  The reason for the 75 \n> watt\nclass\n> is that we want to have as much signal to reach the ISS as  possible.  \n> The\nISS\n> is actually pretty noisy and the radio footprint is very  big and it \n> picks\nup\n> all sorts of interference.  So it helps to have as much  signal get to \n> the astronaut.  Throw in the fact that the ISS superstructure  is so \n> big now\nthat we\n> have had schools have the signal dropout to almost nothing  and you \n> can\nsee\n> that every little bit helps.\n>\n> 2.  The circular polarized beam helps because the signal to and from \n> the\nISS\n> can be bouncing off of the superstructure itself and in some cases the \n> surrounding ground terrain.  As I mentioned above, we have had some\nschools  where\n> the signal dropped out almost to zero.  Luckily the signal (sometimes\nabout a\n> minute later) came back up as the ISS changed its orbital position\nrelative\n> to the ground station and thus some of the blockage was reduced.   I have\ndone\n> 4 school contacts as control op and I use 5x2  LHCP and 10x2 RHCP \n> circular polarized beams with an antenna  switch.  Most of the ARISS \n> telebridge\nstations\n> are using something  similar.  The ISS antennas are basically vertical \n> antennas but the signal  can be deflected all over the place because \n> of\nthe\n> superstructure.   I tend to run my contact on the RHCP beam (but  I am\nready to\n> switch) but we at ARISS have had some reports where the signal did \n> come\nup a bit\n> when using LHCP. Those who are really into satellite work know  that \n> the\nRF\n> pattern does change during a contact so it makes sense to be able to\nswitch\n> polarity.  And don't forget the ISS radio is running maybe 25 watts \n> (or\nmaybe 5\n> depending on the radio used) and can not do any Doppler  correction.\n>\n> 3.  The backup radio is to have a non-directional antenna so that in \n> case\nof\n> rotor or computer failure, the contact can carry on although it will \n> be\nwith\n> a shortened contact time and the quality may suffer.  I have an \n> antenna switch to switch between the 2 antennas during a pass as the \n> RF pattern\nbetween\n> the 2 antennas is completely different.\n>\n> The biggest reason for doing what some may think is overkill is this.\nThe\n> hams involved with a school contact are just the messengers.  The \n> school\nkids,\n> teachers, and parents are the ones we have to satisfy and they  don't \n> understand this ham radio business.  They do understand good audio and \n> no\nscrew ups\n> on the part of the ham crew.  I always tell the schools  that I mentor \n> to\nplan\n> on 600 to 800 people-hours for 10 minutes of contact  time.  They \n> usually think I am nuts until they do the contact and they  often tell \n> me that my estimate was too low.  Think of a school contact as  your \n> worst case Field\nDay; not\n> so much because of the equipment issues but  because of the 600 or so \n> kids watching.\n>\n> Hope this helps a little.\n>\n> 73,\n> Charlie Sufana AJ9N\n> One of the ARISS mentors\n>\n>\n>\n> In a message dated 11/26/2008 4:15:52 A.M. Central Standard Time, \n> [email protected] writes:\n>\n> Ken Owen  wrote:\n> <snip>\n> > From: Paul Je [mailto:[email protected]]\n> > Sent: Monday, November 24, 2008 1:17 PM\n> > To: Ken Owen\n> >  Subject: RE: ISS contact\n> >\n> > Say Ken, we've set up our primary  station just fine, but I was\nwondering if\n> > I could ask for your  advice.  Well, you see, we've tested the\ntransceiver\n> > that we have  (the ICOM IC-V8000), and we can transmit and receive \n> > just\nfine\n> > with it  on our circular-polarized HyGain 2m antenna.  Also, we did \n> > a\nVSWR\n>\n> What kind of antenna?  Anything more than a 3-element Yagi  will be \n> more trouble than it's worth.  Bear in mind that I've  successfully \n> sent and received APRS with the ISS using a homebrew  vertical.  The \n> higher the gain of your Yagi, the more directional it  is, and the \n> more accurately it needs to be pointed.  I find that a  3-element beam \n> is okay for handheld use when working portable, and has  more than \n> enough gain to hit the amateur satellites with 5W from an  HT.\n>\n> > test and our loss is minimal with the 75W transceiver that the  ICOM\n>\n> 75W sounds a bit much, especially into a very directional antenna.\n> You're trying to talk to the ISS, not etch your name on the  side.\n>\n> > produces.  Ok, so here's the problem.  Even with  all the proper \n> > testing done, we still can't seem to pick up or hear  the 166MHz \n> > beacon that the\nISS\n> > produces.\n>\n> Are you using a 166MHz  aerial for this?  Are you sure the beacon is \n> even transmitting when  you think it is?  Your high gain Yagi might \n> well be very very deaf  outside its intended band.  Try making a \n> simple dipole or even a  two-element beam for 166MHz.  With two \n> elements, it will have a more-or-less cardioid pattern, so you \n> shouldn't really even need to steer it much ;-)\n>\n> > My classmates and I are a bit  worried/stressed out.  I mean, just \n> > on\nlast\n> > Friday, we did a test  and someone drove at least 5km away from out\ncollege\n> > and heard us fine  with the handheld radio he had.  We had a signal\nstrength\n> > of 3+  out of 5.  He could've drove out even further, but we felt \n> > that\nwe\n> did\n> > enough testing to know that any attenuation losses were very  minimal.\n>\n> The ISS is pretty much the classic case of  line-of-sight.  There's \n> nothing in the way, and it's only 200 miles  away.  There's nothing to \n> stop the signal anywhere.\n>\n> > Well,  do you know what the problem could be?  Have you heard the\nbeacon?\n> > What does it sound like?  Maybe we should delay or  advance the \n> > rotor by\na\n> > few seconds?   We're using NOVA  software, and it allows us to send our\n> > transmission a few seconds  ahead or behind.\n>\n> Use a wider beamwidth.\n>\n> > Ok, so we  have a circular polarized HyGain antenna hooked up to our\nYaesu\n> >  G5500.  Uhm, this might sound dumb but do you know whether we \n> > should\nbe\n> > right hand circular polarized or left hand circular  polarized?  Is \n> > the\nISS\n> > right hand or left hand on  144.490MHz?\n>\n> This I'm not sure about.  I thought about  building a circular \n> polarised antenna for ISS and amateur satellite work,  but it seemed \n> more trouble than it was worth.  If you've got the  polarisation \n> wrong, it will be incredibly deaf!\n>\n> > I'm trying to  research this, but I'm having the hardest time to \n> > find\nthis\n> >  information out.  Oh, also, since our antenna is \n> > circular-polarized,\ndoes\n> > the way we set our antenna have an effect on our  transmission?  I \n> > know\nthis\n> > sounds confusing, but let me  explain:\n> >\n> > If you looked at our antenna from the front so  that you could see \n> > all\nthe\n> > dipoles/elements both vertically and  horizontally to your view, \n> > well,\n> should\n> > they be perfectly aligned with  one set horizontal and one vertical?\nBoth\n> > the vertical and the  horizontal are perfectly 90degrees to each \n> > other, however, instead of  being a perfect cross to your view, the \n> > elements\nare\n> > more like an \"X\"  to your point of view (even though both are \n> > perfectly 90degrees to  each other).\n>\n> That shouldn't make much of a difference.  Imagine  the signal \n> arriving like a big corkscrew - the key to the circular  polarisation \n> is that the signal arrives at one set of elements and then a  quarter \n> wavelength later arrives at the second.  Now, let's imagine  we've \n> made our circular-polarised aerial by putting two dipoles on a boom,  1/4\n> wavelength apart, and connected them by two equal-length lines.   The\n> vertical one is at the \"front\" of the boom and the horizontal one is \n> to the \"back\", and the up and left elements of the dipoles are  \"hot\".\n>\n> Let's pause reality just as a \"vertical\" peak hits the vertical  dipole.\n> That dipole now has some signal.  Using the  single-Planck-time \n> advance button on our Worldivo (it's like a Tivo for  the fundamental \n> nature of the Universe), we'll step through - tick, tick,  tick, tick\n> - until a quarter wavelength has passed.  Now the vertical  peak is \n> somewhere above the centre of the horizontal dipole - it's picking  up \n> no signal - and there's a horizontal peak about the centre of the \n> vertical dipole - no signal there either.\n>\n> Step forwards another  quarter wave, and there's a vertical dip at the \n> cold end of the vertical  antenna, and the horizontal peak we just saw \n> came in is at the hot end on  the horizontal antenna.  We now have a \n> negative signal on the cold  side of the antenna connection (remember, \n> both dipoles are effectively in  parallel) and a positive signal on \n> the hot side of the antenna connection  - loads of signal!\n>\n> If we reversed the direction of the corkscrew, or  reversed the phase \n> of\n> *one* of the dipoles, then the two signals would  cancel out almost \n> completely.  You can have two signals transmitted  in left and right \n> circular polarisation on the same frequency, and have  *phenomenal* \n> rejection between the two.\n>\n> I should point out that  there's quite a lot in that explanation \n> that's not entirely true, or at  least terribly inaccurate.  It's \n> still a useful model for getting  your head around what seems at first \n> to be a very confusing polarisation  mode.\n>\n> HTH,\n> Gordon\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\nprogram!\n> Subscription settings:  http://amsat.org/mailman/listinfo/amsat-bb\n>\n>\n> **************Life should be easier. So should your homepage. Try the \n> NEW AOL.com.\n>\n(http://www.aol.com/?optin=new-dp&icid=aolcom40vanity&ncid=emlcntaolcom00000\n002)\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_______________________________________________\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",
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}