AMSAT-BB September 2007

176 participants
273 discussions

Call for Papers--2007 ARRL/TAPR Digital Communications Conference

by Ford, Steve, WB8IMY

Technical papers are solicited for presentation at the 26th Annual ARRL and TAPR Digital Communications Conference to be held September 28-30, 2007 in Hartford, Connecticut. These papers will also be published in the Conference Proceedings (you do NOT need to attend the conference to have your paper included in the Proceedings). The submission deadline is July 31, 2007. Please send papers to: Maty Weinberg ARRL 225 Main St Newington, CT 06111 or you can make your submission via e-mail to: maty(a)arrl.org Papers will be published exactly as submitted and authors will retain all rights. 73 . . . Steve, WB8IMY ARRL

9 years, 11 months

FS: Kenwood TS-790A + IFD board + TNC31S

by Francisco Costa, CT1EAT

Dear AMSAT friends My pacsat station is for sale: Kenwood TS-790A 144/432/1200 MHz transciever ============================================ with the following extras: * UT-10 1200 MHz module * Symek IFD-B board (for speed up to 76000 bd) and mods: * extended rx (on 3 bands) * 9600 baud tx/rx * 100ms mute disabled * IFD-B board (38400 baud rx) plus: * Hand microphone * DC cable * Instruction Manual (in english) include schematics * External Control Instruction Manual (in english) * Modifications documentation (in english) All mods were performed by me and no holes were done. This equipment was bought new (1997), and until now there was not a single problem! It was kept on a non smoking environment. Cosmetic is a 8/10 (one minor dent, sort of paint bubble and 4 rotator control box feet "stain", all on top cover) Unfortunatly I don't have the original box anymore. Sorry TNC Symek TNC31S ================ * Tx 9600/Rx 38400 baud card * 128kb RAM * 512kb Flash-EPROM * English mailbox * Kiss autostart including: * RS232 cable plus adapter (DB9) * DC cable * Diskette with software * Original Manuals (english and german) This TNC was bought new (2000), and was used on UO-36 and Tiungsat-1 with great sucess. I did't use it since a long time ago, but I belive it's 100% operational. Cosmetic is 9/10. I will only sale the 2 items together. Price: 1500 Euro Buyer pays shipping. Payment methods: Euro countries: Bank money transfer only! Elsewhere: Western Union or PayPal. Photos: please visit http://ct1eatsale.no.sapo.pt/ Thanks for your attention. See you on P3E or Eagle. 73 F.Costa, CT1EAT www.qsl.net/ct1eat

14 years, 5 months

InstantTrack

by Dave Guimont

Amen on InstantTrack!! IT!!! I was fortunate enuff to be one of the beta testers, many moons ago. I use SatPC32 to control my rotors now, but I always parallel it with IT on another computer to do some of the things that PC32 does not do... I don't know how any serious satellite operator would be without either one, for the pittance they cost in comparison to what they need to do anything on any amateur bird!! Or if one has ANY interest in either the sun or the moon.... 73, Dave wb6llo(a)amsat.org Disagree: I learn.... Pulling for P3E...

14 years, 8 months

Satellite IOTA Award

by Eric H Christensen

I've been considering petitioning the IOTA board to make a special award for IOTA contacts made via satellite. Right now their rules (http://www.rsgbiota.org/rules/rules.pdf, Para C.3.10) do not allow satellite contacts for any award. Are there others here that would support such a petition? 73s, Eric W4OTN

14 years, 8 months

Question about doppler correction software

by Scott Wilson

I have a question regarding software doppler correction - in particular when using linear satellites. I am working on some control software that is a little more flexible than what I've used. I really like SatPC32 on Windows and Predict/gsat on Linux. I haven't yet fallen in love with any available software, but that's really a different story. I can imagine that doppler correction for an FM sat is rather easy in that you simply tune the transmitter/receiver to the published frequencies depending on the operating mode. I'm a little less sure how that would work for a linear satellite. As mentioned before, I do have a chart from AMSAT that lists channelized frequencies for them. If I can tune the transmitter such that the frequency at the satellite is one of the listed frequencies, how sure can I be that the receive is as published? Can I extend that to the point where I would be able to automatically determine frequencies (at the satellite) of the downlink for a given uplink and then compute doppler from there? It would then be fairly convenient to tune within the satellite's passband and let the computer do the 'thinking'. Thanks for any feedback. Scott NW2S

14 years, 8 months

GO-32 APRS experiments Tuesday

by Bob Bruninga

Next Tuesday on the 9 and 10 AM EDT passes over the East Coast, we hope to do a class demonstration via GO-32. We will be looking for other APRS stations and trying to message anyone we see. Mark your calendar if you get a chance. More will be posted later. If anyone can run heir sat station as an IGate, that too would help us capture all packets. thakns Bob WB4APR Naval Academy Satellite Lab

14 years, 8 months

Linux Satellite Tracking

by Bob Stewart

As long as satellite tracking is the subject; gpredict just released version 0.9.0. It looks nice, and seems to have cured the freezes I was getting in the Polar View window. Well done Alex and crew! Bob - AE6RV

14 years, 8 months

Re: SUD (Small Ugly Dish)

by Bob Bruninga

> Back to my "new" [18"] dish... Being that it > is an offset dish, is 1.2GHz possible with > this dish? No. > Anyone tried this? Yes. I tried it for our satellite labs for students and althogh I get about 14 dB or so measured gain with it at 2.4 GHz, at 1.2 GHz, it was nothing more than a big piece of metal giving no more gain than a flat reflector... maybe between 3 to 6 dB. See the photo of its use at 2.4 GHz on the top of this page: http://www.ew.usna.edu/~bruninga/ea467.html With the antenna for one of those $75 wireless camera receivers at the focal point, and the companion little wireless camera as a signal source a mile away with only its 1.5" whip antenna, we receive the picture perfectly with a margin of at least 16 dB. This means the picture would still be good out to maybe 6 miles... It sure is an easy way to get into Amateur TV. Even though it does not even require a license.. But if there are wireless LANS around, then the picture gets lots of QRM.. Bob, Wb4APR

14 years, 8 months

Re: Keep It Simple Silly

by G0MRF＠aol.com

To say the hardware does not not get any simpler is perhaps true for the number of components, but the complexity within those components is much greater than anything flown before in AMSAT transponders. It's probably true to say that Eagle will use 20,000 transistors to do the same job as 20 transistors in Oscar 7. But it's also fair to say those 20,000 transistors will do a much better job. The SDX technology will get its first on orbit test with suitsat2. That will tell us all something about reliability in LEO before launching Eagle and P3E. In 2009 The SSETI ESEO mission to a higher radiation geostationary transfer orbit will include a mode U/S transponder. It converts 435 down to 10.7MHz and that signal can be routed to a software defined transponder or to a conventional linear transponder before being upconverted to 2401MHz. Hopefully, the SDX will perform flawlessly, but should there be a problem, then the satellite can be commanded to bypass the SDX and use a traditional circuit. Somewhere along the line an SDX will be designed that is reliable and give much better performance than whats been flown in the past. It's a learning curve, there may be problems along the way, but we have moved on since October 4th 1957 and we need to investigate new technologies and sort out what works and what does not. Happy 50th birthday Sputnik (I wonder how many valves were inside that?) David G0MRF In a message dated 30/09/2007 16:06:16 GMT Standard Time, hartzell(a)gmail.com writes: Even as a proponent for SDR (and an SDR "user"), the lingering thought in my mind regarding SDX in space is survivability. There is no flight heritage (yet) for an SDX in space, and there is quite a bit of complexity with regards to software and integrated components (ADCs, DACs, FPGAs, CPUs, etc.). But these problems plague analong XPNDRs as well....with the right selection of components, de-rating of components, and rad-hardened when feasible, chances for success increase. 73, Dave n0tgd On 9/30/07, David B. Toth <ve3gyq(a)amsat.org> wrote: > > Patrick: it is too bad that you were unable to join us here in > Hartford, CT this weekend for the TAPR-ARRL DCC ... > There were many presentations on SDR, some by AMSAT personnel ... > > The hardware does not GET any simpler than in SDX ... the HUGE > advantage is that a component with a shifting value (such as might > occur in a spacecraft with wide temperature swings) does not degrade > the performance/optimization of a device, because if the hardware > does age/shift, then that can be compensated for in software ... >

14 years, 8 months

AO-27 scheduler

by John Hackett

AO-27. Easysat ? ... right !!!l. I've been trying (unsuccessfully) to figure out how to tell when the AO-27 transmitter is switched on over my QTH ... (Frei Island JP33WB) ... or not. Of course, any tracking program tells me *WHEN* the satellite is over my QTH but tracking programs don't tell me whether the transmitter is switched on or not. The AO-27 scheduler supposedly does this ... the only problem is ... I find it thoroughly confusing. The passes (according to any tracking program with the latest keps) and the AO-27 scheduler don't seem to agree ... (me'thinks John is doing something wrong !!!) ... or ... from the scheduler I can see if the transmitters are on (or not) when the satellite is well out of my footprint ... but I'd like to know whether it's on when the satellite is workable from my QTH. Is there anyone out there who can explain in words of one syllable (or less) how one figures this out ... and then explain it to a thick and illiterate old sod like me. This mail is in NO WAY meant as any form of criticism of the AO-27 scheduler, it is ENTIRELY me being TOTALLY stupid! and not being able to see the wood for the trees ... and asking for HELP. How about an example that a 5 year old could understand? (Even I might have a chance then). 73 John. <la2qaa(a)amsat.org>

14 years, 8 months

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AMSAT-BB September 2007