October 2008 - AMSAT-BB - mailman.amsat.org

Why choose one language over another - was :Re: Programming language recommendation?
by Eric Fort 06 Oct '08

06 Oct '08

Much of this choice would seem to be based upon what you want to accomplish. My 3 top choices would be PERL which is well supported by CPAN, Python, and C using the gnu compiler collection (gcc). It seems that everyone has a favorite and each has it's merits. Why one language would be chosen over another is a topic probably best answered by others on the listso I'll open that up. Why choose one language over another to code a given task? What makes a language better for one task and not so good for another? Eric AF6EP On Sat, Oct 4, 2008 at 2:55 PM, Alan P. Biddle <APBIDDLE(a)united.net> wrote: > We have a lot of folks here who do programming at a variety of levels. > After a 20+ year hiatus, I am looking to get back into doing a bit of > programming. The intent is not to get into it at a professional level, but > to be able to rip off quick and dirty small programs. Data acquisition, > taking the output of a program and merge and reformat it for specific > purposes, which of course I can do in some cases with Excel, are a couple > of > things which come to mind. It will need the ability to interact with > external hardware. However, the primary purpose is as a brain stretcher > for > someone who once thought F*RTR*N was a real language. > > I am tempted to say that I am looking for the current generation BASIC, but > I am want something a bit beyond that, though of course the ability to > print > "Hello World" with less than 10 lines of code is a plus. ;) And it needs > to be something I can get into using a free or low cost compiler. I am not > much interested in spending a few hundred dollars. > > People have recommended Python, older versions of Delphi, early version of > C, etc, as what I should do. Well, maybe. So if anyone has a good > recommendation, please contact me OFF LIST. And did I say, it needs to be > cheap?! > > > > Alan > WA4SCA > > ----------------------------------- > > What's the opposite of Diversity? > University! > > Catherine McMillan > > > > _______________________________________________ > Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb >

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Re: Mode S advice
by Michael Heim 06 Oct '08

06 Oct '08

Actually, I just looked at the new operating schedule that was just posted. This turns out to be fantastic for me. I have a couple weeks to get things set up, and several days of testing before its switched to V/s while its in L/s. During the testing mode, while its in L/s (I cant transmit mode L yet), I just might put both antennas and converters up and switch between them and make comparisons using several passes, lets say I'm able to catch all of the available passes for 2 days, I can use one unit one day, record my results, use the other antenna the next day, record the results and compare. By the time I can get on and operate, I should have made my choice. Might even try out the DSS dish with the little helix feed on it as Art also suggested. When I do test with that, one of the biggest things I'll be watching for is beamwidth. I am going to venture a guess however that the helix will win out. It sort of makes sense, especially if one does not know the linear polarity the satellite is running, and what sense the signal is coming in to a fixed point while its moving. One thing of note... I am using a linear antenna for V/u, vhf with horizontal elements, vertical 70 cm elements, and I'm quite happy with the arrangement. Therefore, I'll try the linear antenna on 2401 vertical Michael Heim ARS KD0AR ----- Original Message ---- From: Luc Leblanc <lucleblanc6(a)videotron.ca> To: amsat-bb(a)amsat.org Sent: Sunday, October 5, 2008 11:16:36 PM Subject: [amsat-bb] Re: Mode S advice On 5 Oct 2008 at 18:27, Michael Heim wrote: I noticed, while listening in using either antenna, a noticeable amount of deep fades on the bird. I'm not sure if it was caused by reflections nearby, or uplink fades on 1269 mhz. Hi Michael If your fades are on the S band downlink it is you downlink antenna who probably gives you the fades. I tested a standard BBQ grill screen meshed and i also got theses huges fades. When i switched to a linear 42 stacked elements (A WIFI antenna) theses fades disappear completely. as AO-51 S band antenna is linear i guess a linear antenna is the best choice? "-" Luc Leblanc VE2DWE Skype VE2DWE www.qsl.net/ve2dwe WAC BASIC CW PHONE SATELLITE _______________________________________________ Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

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Re: Mode S advice
by Michael Heim 06 Oct '08

06 Oct '08

I want to thank everyone for the advice. Everyone recommends a CP antenna. That's what I'm going to put up. I built one using a wood support that appears to work. One fellow suggests a 60 cm dish. I do have a couple here, one is being used on 10 GHz. The other I may do something with as a portable antenna. I would put the dish up on the mast, but at present, I do not have an elevation rotator, and everything is tilted up about 20-30 degrees. I figure the 12 turn helix by itself would have a wider beamwidth , and yet brings in a pretty darn good signal When the bird gets turned on to V/s, I'lll try to be there too. Michael Heim ARS KD0AR ----- Original Message ---- From: Michael Heim <kd0ar(a)sbcglobal.net> To: AMSAT-BB(a)amsat.org Sent: Saturday, October 4, 2008 7:08:27 PM Subject: [amsat-bb] Mode S advice Last month I was experimenting with mode S receive antennas, and I think I posted some questions on here as to what you guys who are on mode S use. Although I have operated microwave, I have never done so via the satellites. I have 2 options and both appear to work about equally. one involves a linear yagi, the other a helix, RHCP. The last time the bird was in mode S analog, it used mode L for the uplink. I noticed, while listening in using either antenna, a noticeable amount of deep fades on the bird. I'm not sure if it was caused by reflections nearby, or uplink fades on 1269 mhz. Both of these antennas were mounted on a camera tripod about 4 feet off the ground, and there was some metal within about 25 feet or so, which is unavoidable. The antennas will be placed about 15 feet above the ground, and the metal in the vicinity will be below the antenna. So, your advice... should I go with a 16 dbi linear yagi, commercially made for the MMTS band, or the RHCP homebrew 12 turn helix? I am having trouble getting much longer than 12 turns, winding the helix evenly. Is there really an advantage in using either? I guess I'm looking for whatever will do the best as far as fading goes. I am impressed, as the signals were quite strong while using only 2 foot long antennas. By the way, I am building a 1269 TX converter from scratch. I happened upon a brick oscillator that I recrystalled for the proper LO for a 144 IF. The mode S IF is 123 mhz, so there should be no IF leakage problems. Michael Heim Chief Engineer, Forever Broadcasting New Castle PA WKST WJST WWGY 814-671-0666 Chapter Chair, SBE-122 ARS KD0AR _______________________________________________ Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

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Re: AO-51
by Michael Heim 06 Oct '08

06 Oct '08

Well, I accidentally transmitted on 435 into an unswitched 70 cm receive preamp... That would qualify I'm sure, as one of the better ones. Fortunately I realized what I did and ordered 10 replacement transistors, knowing that I'd prolly do it again. Michael Heim ARS KD0AR ----- Original Message ---- From: Luc Leblanc <lucleblanc6(a)videotron.ca> To: amsat-bb(a)amsat.org Sent: Sunday, October 5, 2008 11:17:42 AM Subject: [amsat-bb] Re: AO-51 On 5 Oct 2008 at 9:55, David - KG4ZLB/MØZLB wrote: > Thanks to all who replied both here and off-list, the embarrassing > results of the station investigation reveal a major operator error! :-[ > > > > David > KG4ZLB > The worse one can be your coax not plug in :) but we never know could be you have a better one? That one of you who is faultless may throw the first stone say the tall guy with a beard! "-" Luc Leblanc VE2DWE Skype VE2DWE www.qsl.net/ve2dwe WAC BASIC CW PHONE SATELLITE _______________________________________________ Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

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Coaxial helix
by Luc Leblanc 05 Oct '08

05 Oct '08

I was given an old Helix from a SK estate. It was used in the AO-10 AO-13 era. The helix is made of an RG8-U the inner conductor is connected to an SO-259 and about 1/4 turn from the connector a copper metal plate is soldered to the braid. The round metal reflector is standard but about 10 extension radials are bolted around the plate making the reflector about 30 inches in diameter +- With this kind of reflector it seems to be a VHF helix??? a very odd one!!! If this peculiar design seems to remember something for someone i will appreciate your inputs as i will try to rebuild it as she is in a very poor state. P.S. If this antenna was really existing as it was could be an experimental one by this SK it will make's another alternative to the standard design but as it was made for a back mounting the counter poised should be about 5 pounds!!! quite heavy. "-" Luc Leblanc VE2DWE Skype VE2DWE www.qsl.net/ve2dwe WAC BASIC CW PHONE SATELLITE

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Re: SSB SP-7000 rejection
by WILLIAMS MICHAEL 05 Oct '08

05 Oct '08

Tim, I have a SP-7000 and get some desense, but I think this is the reason. As I key on CW, the noise floor increases depending on the position of the antennas. My antennas are only eight feet above ground. I notice the desense level changes as I rotate. If the antennas are a zero elevation, I get reflections back into the 435 MHz helix antenna from nearby objects. If I point the antennas above the ground clutter, I have no desensing. This is a great preamp. I would try it without the duplexer first. By boom is about 6 ft. I hope this helped. Mike (K9QHO) AMSAT 33589 At 05:37 AM 10/4/2008, Tim Tapio wrote: >Hello all, > >I'm planning a new antenna system and planning on using an SSB preamp on the >430 downlink side. The 7000 uses helical bandfiltering. >My antenna separation will be on an 8' fiberglas boom. Will desense be an >issues? Should I plan on using a bandpass filter such as a duplexer? > >Thanks and 73 de Tim, K4SHF

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Mode S advice (Michael Heim)
by WILLIAMS MICHAEL 05 Oct '08

05 Oct '08

I have built helix antennas from the sites of G6LVB and N4WYK all with PVC. Here are some good websites for 2.4GHz helix antennas. 1. http://webpages.charter.net/n4wyk Click on satellite website, then click on "2401MHz Helix" above the picture of the antenna. 2. http://ve2zaz.net/ Select 2.4 GHz helix. 3. www.g6lvb.com/ Select quadruple helix for AO-40. 4. www.qsl.net/ve3cvg/antennas/2400/ 5. http://members.aol.com/k5oe A site for good reading and links. There are advantages and disadvantages to each type, dish, yagi, or a helix antenna. If I can be of any help, please email me. 73, Mike K9QHO (AMSAT 33589)

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One for the boffins, solved. Thank you.
by Dave Aitch 05 Oct '08

05 Oct '08

Thanks to all who responded. It seems that SatPC32, Orbitron and NOVA will do what I need. 73, Dave. AMSAT UK 5766

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One for the boffins...
by Dave Aitch 05 Oct '08

05 Oct '08

In an effort to plan ahead for some far off satellite operation, I am trying to find software that will show mutual visibility between to known locators, a week or so plus, in advance. Is there such a beast available for us mortals ? Thanks in advance. Dave. G1OCN. AMSAT UK 5766.

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Some more details of XW-1
by Michael Chen, BD5RV 05 Oct '08

05 Oct '08

Hi, guys, Here are some details about upcoming Chinese XW-1: Orbit: Sun Synchronous Orbit Altitude: 499km Inclination: 98 degrees Period: 94 minutes Weight: 35kg Size: 550mm * 350mm Temperature: -20 to +45C Power: Li ion battery: 16Ah Long-term maximum power: 8W Short-term maximum power: 18W Payload: Amateur radio payload: 5.2kg Youngster's experiment payload: 1.6kg CMOS camera: 0.2kg About amateur radio payload: Beacon: 435Mhz, CW 20dBm Linear transponder: RX: 145Mhz, TX: 435Mhz, 40KHz, 30dBm FM Transponder: RX: 145Mhz, TX: 435Mhz, 16KHz, 30dBm Digital store and forward transponder: RX: 145Mhz, TX: 435Mhz, 16KHz, 30dBm 145Mhz RX Antenna: 2dBi, 135 degree, LHCP, unpacked by remote control after entering the orbit. 435Mhz TX antenna: 2dBi, 135 degree, RHCP, unpacked by remote control after entering the orbit. Michael, BD5RV/4

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