December 2006 - AMSAT-BB - mailman.amsat.org

thermal vac chamber
by Nick Pugh 13 Dec '06

13 Dec '06

This is a little off topic but the CAPE team and the University of Louisiana is looking for a deal for a small thermal vacuum chamber. If you know if there is one that can be acquired for something less than a small fortune please let me know off line thanks nick

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AO-51 CTCSS/PL tone
by Andrew Glasbrenner 13 Dec '06

13 Dec '06

The primary FM repeater modes on AO-51 have historically required a 67 Hz subaudible tone to access the satellite. This tone was originally designed to allow the downlink to be switched off when the satellite was not in use. Because of the difficulties in power management between orbits seeing heavy use and those with light use, this scheme is not practical with the current software onboard the satellite. The use of the subaudible tone access has also been problematic when trying to identify the seemingly growing interference issues experienced on most 2 meter uplink frequencies, and when the satellite is over areas of heavy use. Furthermore, despite the near ubiquity of subaudible tone enabled radios in North America, many areas of the world have limited or difficult access to this type of equipment, even in commercial off-the-shelf gear. After careful evaluation and discussion, I have made the decision to suspend the subaudible tone access on AO-51 until such time as it becomes necessary or useful for power management. Please continue to listen to the downlink before and as you transmit to reduce QRMing other users. This means full duplex operation is the most courteous and efficient means of operating the FM satellites. Also, please continue with renewed vigor to help identify and eliminate both non-amateur interference, and amateurs operating outside of the established bandplan that interfere with our satellites. I encourage those with questions or feedback regarding this policy to email me at ko4ma(a)amsat.org, and those with special mode requests to continue to submit them to ao51-modes(a)amsat.org for consideration. The Operations Committee will soon begin to put together the schedule for the upcoming month, and your input is welcome. 73, Drew Glasbrenner KO4MA AMSAT-NA VP Operations AMSAT LM 2332

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Re: Discovery
by Joe Leikhim 13 Dec '06

13 Dec '06

I would expect the main engines might continue run on for a while because or the fuel remaining in the lines and turbo pumps being under tremendous pressure and expansion. Also I think the engine bells are cooled by cryo fuel so some may remain inside as well and some flow desireable to cool down. Perhaps someone more familiar with the engines can describe the shutdown process. It is probably more complex than closing one set of valves so that unburned fuel doesn't burn/explode when the tank seperates. -- Joe Leikhim K4SAT "The RFI-EMI-GUY"© "Treason doth never prosper: what's the reason? For if it prosper, none dare call it treason." "Follow The Money" ;-P

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Re: Is Wi-Fi Headed toward an Early Grave?
by Nate Duehr 13 Dec '06

13 Dec '06

Greg D. wrote: > The wild card in my opinion is Wi-Max (802.16), which is intended to be > the "last mile" connection for service prividers. If this wins, it will > be the death blow to BPL (Yeah!), and will ease the pressure to blanket > Wi-Fi across every major city on the planet. I believe Wi-Max is on > licensed frequencies outside of the Ham bands, so this would be a really > good thing. WiMax may be dead in the water, due to a lack of interest from the service providers already -- in my humble opinion. The service providers already in place, are doing point-to-point last-mile services on 5.3 and 5.8 GHz and have a huge install base they won't want to drop. Examples of the equipment they're using: Trango Wireless, Motorola Canopy Unless the manufacturers of those example systems above make a WiMax product that inter-operates with the existing management tools for managing subscriber units on those other widely-deployed systems, WiMax doesn't stand a chance in anything but new deployments, because the install base is fairly fixed in many areas now. Of course, there will be plenty of new deployments... we'll see if they can compete with the existing providers in areas that already have coverage. Around here we're starting to see the "second stage" of wireless broadband services. The little 802.11 companies are being eaten up by the guys who did their RF equipment "right" with the 5.8 GHz equipment, and point to point high-speed licensed microwave backbone links. Their networks are being yanked out and replaced with these much more manageable units. I remember seeing early stuff where small companies were taking the Lucent 802.11b routers and stuffing them in NEMA boxes -- but we haven't seen those on towers around here in a couple of years. The 5.8 GHz providers are using panel antennas and "sectorizing" their sites, just like cellular. Nate WY0X

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Discovery
by Andrew Glasbrenner 13 Dec '06

13 Dec '06

Gorgeous view of Discovery climbing out tonight from across the state. It gave me a good feeling, especially knowing there are ham radio satellites onboard! 73, Drew KO4MA

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Re: Brace for impact!
by Jerry W 13 Dec '06

13 Dec '06

There is a short video clip on http://www.spaceweather.com/index.cgi of what they call a SOLAR TSUNAMI, amazing! The video was posted today December 8, 2007. If the site updates, check the archive for December 8, 2006 Jerry - K0HZI

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Re: Is Wi-Fi Headed toward an Early Grave?
by David Barber 13 Dec '06

13 Dec '06

Could I perhaps just highlight an unwanted side effect of all the discussion regarding Wi-Fi and its impact on "our" frequencies. Any newcomer reading all the gloom and despondency may well reach the conclusion that 2.4GHz is not worthy of their investment. Surely if we are not careful this becomes self defeating as potential new users shy away and we end up with another under utilised band. The recent scheduling of AO-51 with downlink on 2.4GHz has been interesting. I live in a highly populated urban area with a number of locally active home and commercial Wi-Fi's however using just a K5GNA down converter and corner reflector (hand held) huge interference free signals are easily received. David G8OQW

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Re: Pre amp question
by Bruce Robertson 13 Dec '06

13 Dec '06

Quoting Steve Raas <sraas(a)optonline.net>: > As I prepare for getting on the birds.. I decided to test out this > AG-25 Steve: (Once again, it has to be said that I'm new at this stuff, too, and I'd be happy for the folks on this list who have taught me over the last two years to correct any errors.) What you describe in your letter would, I believe, correspond to the situation in which the noise figure of your preamp is not much better than the noise figure of the front end of your receiver and there is not very much loss between the preamp and the radio (i.e., not very long a run of cable). Is it possible that you hooked it up with a short run of cable in the shack, shorter than you usually use for terrestrial work? Perhaps your receiver nf has improved. If the preamp and the front end have the same noise figure and there is significant loss in the cable, however, you will win with this setup. >From my experience, if your cable is low loss, a 145 preamp isn't as necessary as a 435 one because thermal noise is higher and the cable won't ding you as much. My preamp went funny and it wasn't a complete tragedy. Who knows, maybe *my* 145 preamp is the pits, too :-) Those ICOM units are a bit dodgy, though: they don't seem to specify their noise figures very well. I think all would agree that 435 MHz is the band that *really* needs a preamp. You want one that has a 1 dB noise figure or less for the usual 15 + dB of gain. Advanced Receiver Research and SSB USA are known to be fine. My in-shack ARR preamp is *amazing*. (I have a short run of heliax between antennas and preamp.) Be sure to get one that switches on xmit. As far as setting up a station, I'd try building something minimal to start so that you can observe the improvement each added element brings. Use a female-female N connector in place of a preamp on 145 at first and observe the helpful always-on beacon on VO-52. How high above the horizon does it need to be before you can hear it over the noise? before it starts to move the S-meter? (Don't try this with AO-7; it's too weak.) Even on 435, you'll hear *something* without a preamp if you have an antenna with some directionality. (And, as I've mentioned in the previous letter, even a 1/4w vertical will bring in LO-19 and others.) 73, Bruce VE9QRP

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Re: GeneSat-1 postponed
by Mineo Wakita 13 Dec '06

13 Dec '06

> Wallops announces that Friday, 12/15/06, is now the earliest > possible launch date. Launch time remains 0400-0700 PST for > each day in the current launch window, which has now been > extended from 12/15-22/06. The report on TacSat-2 is that > analysis and testing continue of its flight software and its > ground-based simulator at Kirtland AFB. Web sites to watch > for more information include the NASA TacSat-2 Mission site > and the Wallops TacSat-2 Mission site. http://genesat1.engr.scu.edu/log/opslog.htm > The TACSAT-2/Minotaur 1 launch set for Monday, Dec. 11, has > been delayed with Friday, Dec. 15, as the earliest possible > launch date. Analysis and testing continue on the TacSat-2 > flight software and the ground-based simulator at Kirtland > Air Force Base, N.M. The launch window now extends to Dec. 22. > As information becomes available, updates will be provided. http://www.wff.nasa.gov/webcast/ --------------------------------------------- Name: Mineo Wakita / JE9PEL, JAMSAT member Mail: ei7m-wkt(a)asahi-net.or.jp URL : http://www.ne.jp/asahi/hamradio/je9pel/ QTH : Yokohama Japan, GL:pm95tj Date: Dec 13, 2006 ---------------------------------------------

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GALILEO Green Paper on Satellite Navigation Applications
by Trevor 13 Dec '06

13 Dec '06

>From http://ec.europa.eu/dgs/energy_transport/galileo/green-paper/index_en.htm Document at http://ec.europa.eu/dgs/energy_transport/galileo/green-paper/doc/com_2006_g… Note 5.5 which reads: ---- 5.5. Frequencies ---------------- The international spectrum allocations are done in full compliance with Regulations of the International Telecommunications Union and, in Europe, with the Radio Spectrum Decision Safeguarding the frequency spectrum and promoting the allocation of new frequency bands is a key objective in order to ensure safe and guaranteed service performance for all users. Please note that these issues are also subject to a broader discussion in the context of the review of the EU regulatory framework for electronic communications. Continuous performance improvement is dependent on frequency spectrum allocation. QUESTION 8: Do you foresee the need for a better coordination of spectrum at the international and European level? Should measures be adopted regarding potential sources of interference? ---- Amateur operations in 1260-1300 MHz could be regarded as a potential source of interference to Galileo. 73 Trevor M5AKA --------------- Daily Amateur Radio RSS News: http://www.southgatearc.org/ Email your news items to: editor at southgatearc.org News On Your Website: http://www.southgatearc.org/rss/index.htm News On Your PC: http://www.southgatearc.org/rss/newsreader.htm Upload Your News: http://www.southgatearc.org/news/your_news.htm --------------- Send instant messages to your online friends http://uk.messenger.yahoo.com

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