July 2009 - AMSAT-BB - mailman.amsat.org

Re: The Moon is our Future
by G0MRF＠aol.com 02 Jul '09

02 Jul '09

In a message dated 02/07/2009 13:42:15 GMT Standard Time, ka1rrw(a)yahoo.com writes: Right now this is the concept theory phase. Is a 2m/440 SSB transponder practical? If our analysis proves that it is not, then we can move on higher in frequency until we find an affordable solution (within the ITU guidelines 2m to 440. ? No, too much noise from Earth on 2m and too much path loss on 440. 440 to 2m is a much better solution David

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Re: The Moon is our Future
by Armando Mercado 02 Jul '09

02 Jul '09

Hi Dave, Thanks for your comments. If the "international project" approach were a successful model we would have a constellation of amateur satellites in HEO/GEO flying now. But, different space groups have different priorities. I am not opposed to a lunar repeater, but I think we can get a bigger bang for the buck by pursuing other opitions. To me this sounds like a one time stunt that will take most of our already limited resources. 73's Armando N8IGJ ----- Original Message ----- From: D R Mynatt To: Armando Mercado Sent: Thursday, July 02, 2009 5:28 PM Subject: Re: [amsat-bb] Re: The Moon is our Future A moon repeater/datacom/SSTV/cw whatever else we can do, could be coordinated with *all* the various amateur groups, not just AMSAT-NA. This could make this an international project, similar to ESMO and ASMO projects under way now. It would be financially feasible if, for instance, we landed first (probably not going to happen) and, if I remember correctly, collect the cash prize for the first non-commercial moon landing. I think that's still out there, isn't it? Dave//KA0SWT

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Re: Has anyone considered???
by MM 02 Jul '09

02 Jul '09

Yes, Digital is an option. However, i would want it to pass through the analog transponder unprocessed. The reason is that we can't afford the Million dollar Radiation hardened chips to support digital processing required on satellites. DSP or SDR will add to the Cost and add many years to the project. WE need projects much faster than have been delivered in the past, 1-2 year schedules not 10 year schedules. Miles --- On Thu, 7/2/09, Jack K. <kd1pe.1(a)gmail.com> wrote: > From: Jack K. <kd1pe.1(a)gmail.com> > Subject: Has anyone considered??? > To: bruninga(a)usna.edu, "'Joe'" <nss(a)mwt.net>, "'MM'" <ka1rrw(a)yahoo.com> > Cc: amsat-bb(a)amsat.org, kg4zlb(a)gmail.com > Date: Thursday, July 2, 2009, 8:40 AM > Has anyone considered the notion that > the communications from a HEO or Moon or Mars need not be > analog? Has anyone considered a digital mode such as WSJT > for comms? I know for a fact people are running meteor > scatter and EME using a single beam (albeit a long one) and > 150 watts. This is not out of the reach of most hams and it > is not non-viable communications mode... Heck the US Navy > even ran RTTY in the 60's from Hawaii to Maryland as a > normal mode of communications (yes it was big and wieldy, I > just mentioned it as an aside). > > DE - KD1PE - Jack > > > > >> Why go with the minimal antenna gain? > >> ... any antenna with a 3 db point that exceeds > >> 6.5 degrees is just wasting transmitter power. > > > > I think that would be about a 24 dB gain > antenna. Pretty big > > and would take some careful alignment... Kinda > like a realy big > > EME array > > > >> Just remember what an Oscar 10 station took > >> to have reliable communications, At Apogee > >> it was only 35,000 miles away, the Moon is ...] > >> [250,000 miles] > > > > Which is 7 times farther, squared or 50 times more > power (about > > 17 dB). > > > >

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Moon project: why not a passive refeector?
by andy thomas 02 Jul '09

02 Jul '09

Guys, taking a tip from ECHO, why not improve the EME link budget by building a structure of resonant cavities at 2m or 70cm, and above? Such a structure could be built by a metallic (reflective) polymer surface "bubble" or pyramid, and an automatic system to inject hardening-foam to give it rigidity. Our beams on earth would point to the structure at a target frequency and the increased reflectivity of the structure would bring EME possible for more modest arrays. Would bring OSCAR-0 into the backyard... justa thought... andy G0SFJ

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Re: DO-64 software support for PSK-1(T) hardware?
by PE0SAT 02 Jul '09

02 Jul '09

On Thu, July 2, 2009 21:59, Greg Beat wrote: Hi Greg, > I see that DO-64 / Delfi-C3 has a 1200 baud BPSK downlink and their RASCAL software uses the computer's soundcard DSP for decoding. > > Does the RASCAL software have an ability to support data stream from the PacComm PSK-1 combo? Look for Warble, it can be found on http://members.casema.nl/b.ubbels/pe4wj.htm Goodluck > ==== > w9gb -- With regards PE0SAT Internet web-page http://www.ham.vgnet.nl/

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24 Ghz stats
by Howie 02 Jul '09

02 Jul '09

In response to Joe, W9SBD, at 24 Ghz: 6' antenna = 51 dB gain, 3dB BW = .4 deg, EIRP @1W = 126 KW 4' antenna = 48 dB gain, 3dB BW = .6 deg, EIRP @1W = 63 KW 18" antenna = 39 dB gain, 3dB BW = 1.6 deg, EIRP @1W = 8 KW All figures rounded to next whole number, gains assume 65% efficiency. We have excellent space allocations at 3.4 GHz for downlink that would be very inexpensive to build. Even a high end 30 deg./K LNB with external 10 MHz. reference is less than $500 new and will convert 3.4 Ghz to 950 Mhz. The used price is much lower. I have sketched out some ideas to compensate and downconvert a really cheap ($50) DRO LNB to a 432 MHz. IF using mostly off the shelf parts. This band is great for space comms and can use very inexpensive commercial parts. There is very little terrestrial activity to worry about and this band is not allocated for commercial downlinks in this region. In areas where it is allocated, the frequencies below 3.410 don't seem to be popular commercially. Howie AB2S

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DO-64 software support for PSK-1(T) hardware?
by Greg Beat 02 Jul '09

02 Jul '09

I see that DO-64 / Delfi-C3 has a 1200 baud BPSK downlink and their RASCAL software uses the computer's soundcard DSP for decoding. Does the RASCAL software have an ability to support data stream from the PacComm PSK-1 combo? DO-64 Frequencies: a.. Primary telemetry downlink: 145.870 MHz 1200 Baud BPSK AX.25 400mW b.. Backup telemetry downlink: 145.930 MHz 1200 Baud BPSK AX.25 400mW c.. Linear transponder passband downlink: 145.880 - 145.920 MHz (inverting) 400mW PEP d.. Linear transponder passband uplink: 435.570 - 435.530 MHz e.. Transponder mode beacon: 145.870 MHz CW (10dB below transponder PEP) ==== w9gb

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Re: The Moon is our Future
by MM 02 Jul '09

02 Jul '09

Hi W0JT: I like your simple explanation of the path loss; it should help many understand that an Active Repeater on the Moon will not require as big of an antenna system as passive Moon EME station. Now we just need to run the path loss numbers a few different ways to see which Amateur Radio Band option works the best. If we are able to piggyback on a NASA funded Unmanned Moon lander, then we have the possibility of the least expensive flight to High orbit possible. This is an opportunity we just can not miss trying for. Our only other option for affordable high orbit flight may be with China. I believe the High orbit flights with NASA and EAS are now cost prohibitive. 73 Miles WF1F MarexMG.org --- On Thu, 7/2/09, tosca005(a)umn.edu <tosca005(a)umn.edu> wrote: > From: tosca005(a)umn.edu <tosca005(a)umn.edu> > Subject: [amsat-bb] Re: The Moon is our Future > To: amsat-bb(a)amsat.org > Date: Thursday, July 2, 2009, 11:52 AM > On Jul 2 2009, kd8bxp(a)aol.com > wrote: > > > Don't want to get a whole new thing started here but - > I don't think we > > ever went to the moon in 1969 and I don't think we > will ever goto the > > moon - in 2012 or whenever they proposed a "return" to > the moon > > With that level of disbelief I can certainly see why you > are predisposed to > discount the possibility of a moon-based transponder. > > > I would love to see an amatuer repeater on the moon > thou - from my > > understanding EME is expensive to do, so I think it > would leave most of > > us out > > Not necessarily. Remember, with conventional EME, you send > as large a > signal as you can muster towards the moon, incur huge path > losses along the > way, then incur a huge loss because the moon is a very > imperfect reflector > of RF energy, then incur the huge path loss back from moon > to earth. > > With a moon-based repeater, you send as large a signal as > you can muster > towards the moon, incur the same path loss from earth to > moon; BUT, THEN > you enlarge the signal with a gain antenna at the repeater, > and then have a > sensitive receiver that can detect and amplify the signal. > The repeater > then transponds the signal to a different frequency band, > amplifies it as > much as equipment weight and power availability allow, > transmit it through > a gain antenna, and only THEN incur the huge path loss from > moon to earth. > > Because the path loss is only in a single direction, and > instead of an > inefficient (lossy) passive reflector, you have gain > antennas for reception > and transmission, plus amplification on receive and on > transmit, the net > earth station requirements should be much less than > conventional EME. > > That's not to say it would be easy, just that it should be > easier than > conventional EME in terms of station requirements on earth. > As has been > mentioned numerous times already, the station requirements > for the space > end of the system are enormously more difficult than > anything we've ever > tackled so far with either LEO or HEO satellites. > > But there's no harm in DISCUSSING the idea, and learning > about the pitfalls > and possibilities as part of the discussion. Even if it > never comes to > pass, we should all be a bit more knowledgeable after > having had the > discussion. > > As far as the dreaming goes, wouldn't an L/S transponder be > better than a > V/U or U/V transponder? Granted, the path loss is greater, > but the antenna > gain is easier to produce... > > While I am a firm believer in the KISS principle (Keep It > Simple, Stupid!), > I am getting a little tired of hearing people complain > endlessly about the > downfall of AO-40 being due to its complexity. Uhh, the > downfall of AO-40 > was human error, which will ALWAYS be an issue. The only > reason that AO-40 > was ever usable at all was BECAUSE of its complexity, i.e., > the redundancy > of multiple transponders that could be switched into place > after initial > failures, etc. OF COURSE, a mission to the moon needs to be > as light and > compact as it can be made, and therefore much simpler than > AO-40, but due > to the harsh environment in which it would be asked to > operate, it needs to > be as complex as necessary to get the job done, i.e. not as > simple as AO-10 > or AO-13. > > 73 de W0JT > AMSAT-NA LM#2292 > > _______________________________________________ > 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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Richard Garriott qsl
by Perry Yantis 02 Jul '09

02 Jul '09

I received my qsl today from Richard Garriott. Perry WB8OTH

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AMSAT Journal
by Ed Long 02 Jul '09

02 Jul '09

Everyone, The May/June issue of The AMSAT Journal was just uploaded to the printer. This one was a bit late too due to some content delays, but it is finished and I think it's a great issue. Hope you enjoy it. The Editorial team worked hard on it. 73 and have a very happy and safe July 4th (for those of you in the US), Ed Long WA4SWJ Editor, The AMSAT Journal ----

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