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@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@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 ...
----- Original Message ----- From: G0MRF@aol.com To: amsat-bb@amsat.org Sent: Sunday, September 30, 2007 21:01 Subject: [amsat-bb] Re: Keep It Simple Silly
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.
....hmmm, and its also unfair to don't say that, the possibility for a malfuction with 20,000 vs 20 transistors is .... 1,000 times greater !
Simple mathematics... even if these 20,000 transistors do a better job, the risk is too big.
73, Mak SV1BSX
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At 05:23 AM 10/1/2007, SV1BSX wrote:
....hmmm, and its also unfair to don't say that, the possibility for a malfuction with 20,000 vs 20 transistors is .... 1,000 times greater !
Simple mathematics... even if these 20,000 transistors do a better job, the risk is too big.
Well, I don't think the risk of failure should be keeping us in the 1970's. Sure, the SDX is untested, but so was every other technology that is used in space at one stage. If you don't take the risk, you don't learn how to enable these things to survive in space either. I certainly like the idea of a backup analog transponder, so that the satellite can perform some useful function, even if its primary "experiment" fails. Having older technology alongside the new also gives a benchmark to compare against, in terms of how they degrade over time in the space environment.
Oh, and we don't seem to get the same complaints about the digital birds that have been flying for over 2 decades, or newer and more complex IHUs that have flown. The way I see it, is new technology has to be flown when the risks seem acceptable to make it worth putting into space. I don't have a problem with having backup, in case the experiment fails (obviously, there is a weight penalty here), but my question is whether there is really any value in an am Amateur satellite service that does little more than puts "more of the same old stuff" in orbit. Shouldn't be putting some of our energy into finding out how to safely use new technologies in the space environment at an affordable cost?
73 de VK3JED http://vkradio.com
Can I offer my viewpoint as a newcomer and a relative outsider?
From my POV, AO-7 is the most successful amateur satellite
ever made. It's the energizer bunny of satellites, it has a large footprint, and a long hang-time. To top it off, it's easy to access for someone with few financial and technical resources.
I've seen a few comments about AO-40, but where is it? Again, from my POV, it's a proof of concept that needs to be followed up with a working model.
It's very nice that there is a satellite going to mars. But, will I ever get any benefit from it, other than an warm fuzzy feeling that some engineers with access to mega-equipment and big money to pursue their hobby also happen to be hams? Not likely.
As far as digital stuff goes, well, yawn. I find it totally disinteresting, but I'm happy that it's there for the people who enjoy it. When digital communications gets to the reliability level of analog, then someone please wake me. I don't mean to be insulting, but I just don't see it happening because of the direction digital has taken. When I was a programmer, we addressed something similar when our customers wanted to go from UDP to TCP. We were just barely able to convince them that UDP would serve their needs better. It's all well and good that what you get is 100% what was sent, but the bands are too crowded and the ether is too unpredictable to make that 100% an actual 100%.
OTOH, I'd love to see Amsat put something on the moon, but I don't think there's any free money available. If that $20 million were within easy reach, someone else would already have plucked it. But, I'd love to see a U/V transponder on the moon, because I simply do not have the resources to put up an EME station, and I probably never will.
To sum it up, I've spent most of my years in ham radio on HF. I like the idea of being able to contact people in foreign countries. Two of my most exciting contacts on satellite were with VO10R and our own VE9QRP. Because of my QTH and finances, I'm not sure if I'll ever be able to contact Hawaii or Alaska via satellite. Europe is a dream that's probably way out reach. In any case, what works for me are challenges that are just meetable with my resources. IMHO, projects that are usable by an ever narrowing group of people (microwaves, nanowaves, extremely weak signals, etc) are doomed to an eventual failure of large-scale support.
KISS
Bob - AE6RV
At 02:27 PM 9/30/2007, you wrote:
Can I offer my viewpoint as a newcomer and a relative outsider?
Bob, there are no OUTSIDERS in amateur radio...I've been licensed for 57 years, have operated the amateur satellites for 28 years, and have operated everyone launched since then, analog/digital/am/cw/ssb/fm. Have hundreds of QSL cards to prove it, and have made well over 7000 logged ssb/cw amateur satellite contacts. And I've been helped by dozens of other hams, since then, and still need it once in awhile for things I've forgotten...I'm 85. AO7 was my first one by the way, and I operated it then(1980) with wa5zib, Andy (he has a new callsign w5acm, I believe) and operated AO7 with him again on 21mar 04.....when it miraculously came back to life!!
So don't let any of the Johnny-Come-Lately's on here (and there are some, with responses that sound as tho they were licensed yesterday) cause any grief!!
A good idea to start is with the THE RADIO AMATEUR'S SATELLITE HANDBOOK by Marty Davidson if you don't have it..
From my POV, AO-7 is the most successful amateur satellite
ever made. It's the energizer bunny of satellites, it has a large footprint, and a long hang-time. To top it off, it's easy to access for someone with few financial and technical resources.
I've seen a few comments about AO-40, but where is it? Again, from my POV, it's a proof of concept that needs to be followed up with a working model.
To sum it up, I've spent most of my years in ham radio on HF. I like the idea of being able to contact people in foreign countries.
Me too, and I've talked to over a hundred on the satellites!
A lot of us understand your dilemma. AO40 and other high altitude sats enabled worldwide communications with enough bandwidth, that I've never heard of anyone being able to get on...Some times sounded like 20 meters at sunspot high, but that's the fun of ham radio....Most of those have deserted the reflector because of a lot of the crud that is on here, but just hold on until P3D is launched!!!
Google Peter Guelzow DB2OS, and it will tell a bunch about P3D.
But I am interested in ham progress to the moon, mars, and anything else that can be dreamed up, but I want any small contribution that I have or might make to got to development of a high orbit satellite, and not some dumb 2 user FM bird. (That we have circling us now!)
OK, there's my oar, it's been bent before so go ahead!!
73, Dave wb6llo@amsat.org Disagree: I learn....
Pulling for P3E...
At 05:27 PM 9/30/2007, Bob Stewart wrote:
I've seen a few comments about AO-40, but where is it?
It's motor blew up, and that wasn't really new technology - someone forgot to remove a pin.
As far as digital stuff goes, well, yawn. I find it totally disinteresting, but I'm happy that it's there for the people who enjoy it. When digital communications gets to the reliability level of analog, then someone please wake me. I don't mean to be insulting, but I just don't see it happening because of the direction digital has taken.
Digital is more than sending keyboard to keyboard or files. It is digital voice. It is Software-Defined Radio and transponders. The SDX(s) in the Advanced Communication Package(s) is designed to make it possible for folks with antenna restrictions to work satellites with nothing more than a dish the size of one for DirecTV .
To sum it up, I've spent most of my years in ham radio on HF. I like the idea of being able to contact people in foreign countries. Two of my most exciting contacts on satellite were with VO10R and our own VE9QRP. Because of my QTH and finances, I'm not sure if I'll ever be able to contact Hawaii or Alaska via satellite. Europe is a dream that's probably way out reach. In any case, what works for me are challenges that are just meetable with my resources.
See above re the reduced requirements for ground stations. Sounds like just what you are looking for ... stay tuned for info re future world-wide coverage 24/7 by satellite.
IMHO, projects that are usable by an ever narrowing group of people (microwaves, nanowaves, extremely weak signals, etc) are doomed to an eventual failure of large-scale support.
We are already doomed to extinction if we do not make fundamental changes. The average age of US hams is 57 yr., and it is rising by 1 yr. per yr. Do the math and you see if we do not make it more relevant to young people, then it will not matter. Simply looking to HF and DXing and contesting to excite kids is not going to do it. If it was, we would have seen it already. Check with the kids - it's a digital world out there. If we build for the old and disgruntled, then with all due respect we are building our own coffins.
Lest you think this is being done to exclude people, nothing could be further from the truth .... the goal is to accommodate many people with simpler antennas and gear.
Really.
73, Dave VE3GYQ/W8 Spencerville, OH
At 01:51 PM 10/1/2007, David B. Toth wrote:
At 05:27 PM 9/30/2007, Bob Stewart wrote:
I've seen a few comments about AO-40, but where is it?
It's motor blew up, and that wasn't really new technology - someone forgot to remove a pin.
I have to agree, we do have to keep up with technology. Sure, the Amateur service is unique in that old modes can always find a niche, but we need to explore the newer techniques. And I certainly agree with the demographics. It's the only hobby interest of mine (and I have a number) where I am still seen as "young" (and I'm 40 next year). In all of the others, I fall somewhere between the median age and the older end of the spectrum.
I for one look forward to what the satellite community will dream up. I was looking forward to AO-40 and was disappointed when the incident happened, but there's always the next bird to look forward to. :-)
73 de VK3JED http://vkradio.com
At 03:23 PM 9/30/2007, SV1BSX wrote:
----- Original Message ----- From: G0MRF@aol.com To: amsat-bb@amsat.org Sent: Sunday, September 30, 2007 21:01 Subject: [amsat-bb] Re: Keep It Simple Silly
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.
....hmmm, and its also unfair to don't say that, the possibility for a malfuction with 20,000 vs 20 transistors is .... 1,000 times greater !
Simple mathematics... even if these 20,000 transistors do a better job, the risk is too big.
Even simpler math ... 1 out of 20 failing is likely worse than 1 out of 20,000 ...
G0MRF is correct of course ... SuitSat-2 will test the SDX ...
I'm not sure where anyone thinks this "debate" is going - it IS going to be an SDX and not analog ... this has already been decided on as far as I can see ... and I sat through a lot of talks at the DCC about this stuff. Because that is: a) what the guys doing all of the work want to do, and b) what is required to provide the services desired for the power budget available.
However, we might be able to put a spark-gap up there if we need something "rad-hardened" ...
<sigh>
Dave
Hi Dave,
I'm not sure if Sputnik had VALVES, but it might have had TUBES! ;-)
Happy Birthday Sputnik,
Dave n0tgd
On 9/30/07, G0MRF@aol.com G0MRF@aol.com wrote:
Happy 50th birthday Sputnik (I wonder how many valves were inside that?)
participants (7)
-
Bob Stewart -
Dave Guimont -
Dave hartzell -
David B. Toth -
G0MRF＠aol.com -
SV1BSX -
Tony Langdon