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AO-51 Mode L/S.
by Dave G1OCN 12 Sep '06

12 Sep '06

Anyone for a go across the pond at 2248 UTC ? Cheers, Dave. Portland. Dorset. IO80SM

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Re: 50 MHz (was S band and Eagle: an appeal for a higherleveldiscussion)
by Tom Clark, K3IO 12 Sep '06

12 Sep '06

Trevor, M5AKA asked > What are peoples views on trying to get an Amateur Satellite Service allocation > at 50-51 MHz ? On time scales of 10 years (i.e. soon enough to be applicable to any of the ongoing decisions), IMHO the chances are somewhere between "microscopically slim" and "no way in hell". Any change like this has to be proposed to the ITU (usually by the IARU) by some national delegation (BTW -- the head of delegation has Ambassadorial status) at a WRC. If the proposal isn't laughed out of the house instantly, it will be referred to the ITU's Study Groups for presentation at a subsequent WRC. Then the topic might be placed in front of the ITU, where it it might be adopted. The ITU's recommendations must then be ratified as a treaty by the nations involved. Here in the USA, it is offered up by the President (if he/she cares) to be ratified by the Senate (a political process that hasn't been going too swiftly on this side of the pond -- witness Kyoto). To squeeze out spectrum for Galileo (& the other proposed new GNSS systems) -- which involves gigaEuro financial issues -- took at least 3 WRC cycles (if I count right) -- i.e. 10++ years. BTW -- Since we'd have to have the first fight just in the IARU in order to have the chance of getting the ideas considered by the ITU/WRC cycle, the initial fight would be 6M vs more world-wide 40M spectrum; and I note that the IARU has a heavy pro-HF bias. Personally, if we were going to fight a battle, I'd rather see us fight for an S2 = 3400-3410 MHz allocation in R1. 73, Tom

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S band and Eagle: an appeal for a higher level discussion
by Bruce Robertson 12 Sep '06

12 Sep '06

There has been a recent restatement of disappointment regarding the Eagle design committee's recent choice to use S band as an uplink not a downlink. Note that the next two HEO's scheduled to launch *will* have S band downlinks, so there's no worry that people like I, who live in radio quiet areas, will be unable to use our developing S band equipment in the future. As I understand it, the Eagle design team have used standard predictions of 801.11 usage to determine mathematically that by the time of launch the radio environment will simply not support reliable communications. I cannot imagine that they like these conclusions. Implementing new bands entails new risks, after all. But numbers don't lie (or shouldn't), and it would be a horrible disservice to all of us if they designed and launched a bird that was effectively mute at launch. The design team have said again and again on this list that they would welcome contradicting evidence that is cogent, and I, for one, believe them. They're our volunteers, and they deserve our support. I can't provide that contradicting evidence: I'm not skilled or qualified. But I can assess an argument, and the responses so far have not been nearly as rigorous. They have amounted to "works for me", which I think misses the point. Please, please, those of you who are qualified and competent and hold the opposing opinion, take the design committee at their word and assess their work, check their assumptions, present cogent opposing arguments. There is some thought that a dish antenna properly implemented will overcome the obstacles described by the design team. Let's model this. Or those who live in heavy 802.11b environments, do some experiements with terrestrial links (which I suppose could be assumed worse than earth/sky). Who knows? Maybe it's all like my last tax return, where a missed decimal point made me think I'd have to take out a second mortgage to pay our taxes :-) This list and the wiki exist so that we can undertake that sort of dialogue, and for my part, it is my favorite part of participation in AMSAT. Some have suggested that Eagle fly with an S-band downlink on the off chance that it *does* work despite the theory; others, that we survey the members to see what they'd like. I fully support the design teams rejection of the former approach. Launch weight is very expensive and the kitchen sink approach is not to my mind sensible. As to the latter, a survey presumably pertains only to *working* bands, not ones that are polluted out of existance. It's human nature for us more readily to see our misfortunes as caused by the malace of others, but I think we should strongly avoid terms like "bait and switch". We'll get much further if we all assume the goodwill of everyone involved. 73, Bruce VE9QRP

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Re: Planning for the future, downconverter options
by jules＠g0nzo.co.uk 12 Sep '06

12 Sep '06

Micheal, You can use it right now on AO51 ! Jules ----- Original Message ----- From: "Michael Tondee" <mat_62(a)netcommander.com> To: "Vince Fiscus, KB7ADL" <vlfiscus(a)mcn.net> Cc: <amsat-bb(a)amsat.org> Sent: Monday, September 11, 2006 10:33 PM Subject: [amsat-bb] Re: Planning for the future, downconverter options. > At the rate things seem to be going. I would avoid planning anything > for the future until the designers figure out exactly what it is they want. > I planned for the future a year ago and bought a dish and AIDC 3731 for > S band. Now according to the "experts", it's going to be useless in a > short while! > 73, > Michael, W4HIJ > AMsat # 36017 Hi Michael, W4HIJ You can use the actual S-band setup when P3E will be in orbit. Read please http://www.amsat-dl.org/pic/gallery2/main.php?g2_view=core.DownloadItem&g2_i temId=6497 A 5.6 MB long pdf file about P3E 73" de i8CVS Domenico

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Re: SDX transponder timing delay measurements?
by Tom Clark, K3IO 12 Sep '06

12 Sep '06

Ken wrote: >> As a design goal, it would be helpful to the >> OD process if the delay could be made consistent >> within about +/-5 micro-sec -- i.e., 1500 meters >> (smaller is better). It is also important to >> quantify the standard deviation to that bias is >> since that is also factored into the OD process. Let me chime in since this is one of my specialty areas. It has been my hope/plan that the delays will be very accurately calibrated, and that we will have "certified" ground stations that are also well calibrated. I've been pushing to have ALL local oscillators on EAGLE and all timing clocks (remember that the 100-200 kb/s sampling clock is yet one more LO in the system) derived from a single, high stability clock. In addition to ranging, it is my hope that we can have an amateur, global time synchronization capability at the usec level. When (occasionally) it is time to do the ranging task, it might be necessary to swap in a different, optimized software into the SDX -- this would be my backup just in case the delay is not deterministic when normal SDX is running. Even if the delays are not as accurately determined as I hope, I see no reason that they will not be stable over times of minutes. With this being true, then we can do very accurate DIFFERENTIAL delays using N "certified" ground stations. If you do this at ~20,000 km range with stations ~1 earth radii, the difference observable only suffers from a factor ~3 degradation. Every ground station pair you add (the number of pairs M increases with the number of stations N as M=(N)*(N-1)/2) gives a statistical improvement of of sqrt(M-1); hence the geometrical loss from using a differenced observable is easily made up on the ground. 73, Tom

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SDX transponder timing delay measurements?
by Douglas Quagliana 12 Sep '06

12 Sep '06

I know the design isn't even done yet, but has anyone ever measured the time delay of an RF signal *through* the (demo) version of SDX? That is, how much time would it take for the signal to go from the receiver's antenna through all the electronics, and out the transmitter's antenna? Can someone put this on "the plan" so that it's measured before launch? Douglas KA2UPW/5

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Crowne Plaza Reservations
by Emily Clarke 12 Sep '06

12 Sep '06

It looks like the Crowne Plaza has run out of rooms for the core period (6th, 7th and 8th) of the Symposium in our block, however we are working with them to see if we can increase the block size. It may or may not be possible as they indicated are nearing capacity. To assist you in finding suitable accommodations nearby (hopefully within walking distance) we have contacted other hotels in the area. There are plenty of rooms available and we are negotiating a group rate with one of them. I will provide additional information to you as soon as is possible. Thank-you for your patience! 73, Emily --------------------------------- N1DID formerly W0EEC - CM87tm Support Project OSCAR - http://www.projectoscar.net

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LVB tracker, USB interface boards on eBay.
by jules＠g0nzo.co.uk 12 Sep '06

12 Sep '06

All I have just seen these items. The look to be the modules that Howard designed his LVB tracker board to accept. Will give your LVB tracker an on-board USB interface. http://cgi.ebay.co.uk/USB-Serial-interface-module_W0QQitemZ160009996603QQih… Jules

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Eagle-S
by WILLIAMS MICHAEL 12 Sep '06

12 Sep '06

I'm waiting for AMSAT-DL to announce it's abandoning P3E's S-band downlink system based on AMSAT-NA's recent data. It would put an end to this. Nobody seems to put my 5 GHz phones back in their chargers when done. Mike K9QHO AMSAT 33589

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(no subject)
by David J 12 Sep '06

12 Sep '06

The Florida AMSAT Net will meet this Thursday evening at the usual time of 19:30 ET, 23:30 UTC on the West Florida Group Ni4CE repeater system, the Orlando N4HHA repeater at 443.1 MHz, 103.5Hz tone, the N4LEM Cocoa repeater, 147.36 MHz +107.2 PL or connect by echolink to KG4YZY-R. The net's purpose is to provide a platform for hams with amateur satellite interest to meet and discuss topics of interest. All amateurs are invited to check in. Dave, AA4KN

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