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

S band or any backup?
by G0MRF＠aol.com 10 Sep '06

10 Sep '06

On the subject of a parallel S band TX. That may or may not be simple depending on what else is available inside Eagle. But in any event it should not require switches. About two years ago when there was a similar period of outrage on the BB, the hot topic was the wisdom of flying an untried or tested SDX transponder without a switchable conventional 'linear' backup. I beleieve it was Bob who announced "There will be no conventional linear transponder in Eagle" I was very pleased to see Rick, W2GPS, leap quickly into the debate and reassure everyone that the complicated DSP + logic in the SDX would be backed up by conventional linear electronics. 'just in case' In a recent mail the UV transponder has been referred to as having unbelievably high audio quality. An apparent and very well justified comment on the quality of the SDX. What I can't recall seeing, is any reference to any fall back position of a linear system as a back up. It's worth remembering that 3 - 5 years time will be the peak of the sunspot cycle. High solar activity, or an unfortunate error with the orbital change burn as AO-10, could result in the satellite receiving a great deal of radiation. It would be good to know that the linear backup plans have not been quietly filed in the waste paper basket. If it hasn't, then a parallel transmitter for S or any other band is very simple to implement. Just split the IF, wire the other transmitter in parallel. 5W to an S band patch or whatever, and control it by turning the DC power line on or off. S band amplifiers no longer need to run in class A with 30% efficiencies, so an up to date class AB design would not be a large burden on the power budget. I suppose my quiet concern is not really the lack of S band, but; If the SDX or 2m TX fails, what is left in the current design to provide a service to the 90+% who will not have, or are not interested in C band? Good engineering is important, but planing for the unexpected is vital. Incidentally. It occurs to me that a disadvantage of having one major UV transponder operating 24/7 is that while that concept removes the need for complicated scheduling it will occupy 100kHz or so of the 2m band permanently which may not be totally desirable in a limited 200kHz bandwidth. Presumably with Eagle 2 and 3 under design / construction at the time of launch they will have differnt bands. - Maybe 2390 - 2400 ish Enjoying the debate David G0MRF

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S-Band Down Link P3E/Eagle
by WILLIAMS MICHAEL 10 Sep '06

10 Sep '06

One thing is certain, P3E will provide a real world test of S-band down link capability. It will then be perfectly clear if the decision to delete it from the Eagle was a wise choice. Mike K9QHO AMSAT 33589

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HT Mindset
by sco＠sco-inc.com 09 Sep '06

09 Sep '06

HTs are nice. I have been reading about the plans for Eagle and how it must serve the HT and CC&R community of hams. Thats fine, when Eagle is close to Earth HT users can work it. But when Eagle is 40,000 km out in space that is when the larger tracking antenna arrays should come into their own. That lets both camps (HTs and tracking arrays) use and enjoy the next HEO satellite. CC&R restrictions should be taken care of with new state laws like PRB-1 to allow Hams to have antennas on their property that asist in case of natural disasters and in the war with Islamic Facists. If the goal is to launch 3 HEO sats over a 13 year period that means design and build one style spaceframe then change the insides as more modern technology is developed over the time span waiting for launch. P3E seems to be using a tried and true spaceframe. Why did Eagle need to be different? If there are plans for a 2nd P3E #2 or #3 that would interest me more than Eagle #1 with unproven ideas. Let most of the experimentation take place in the ground stations, not in space (at least not until we can send a repairman to space to fix it). Can't PSK31 work thru a HEO using very small V and U band antennas for one thing? Let the digital crowd do that and let the SSB folks use their tracking arrays to work voice on V and U and yes even S band if the users want to try it (thru the future interference). Maybe by then we will be using digital voice with techniques to work thru the interference on S band. Are we just going to give up and move to a higher band everytime a few commercial users get on one of our bands? Why? It may take 13 years to design, build and launch the first Eagle. You can not launch 3 Eagles in 13 years with the way you are going now. Just a few thoughts from a ham satellite user. Les W4SCO

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S-band on Eagle
by Jim Sanford 09 Sep '06

09 Sep '06

Ladies and gentlemen: I have been reading the comments regarding the Eagle S-band downlink decision. I herewith respond to some. All along, the Eagle project has put a premium on hard science, rigorous peer review, and dispassionate analysis. All along we knew there might or would be some changes to what we've been planning. With several other issues on the move or decided, we took a few days in late June to hammer out, based on science, the transponder situation. We did multiple, independent link analyses, and all came to the same conclusion. We validated interference predictions with measurements that have been taken. The conclusion is that S-band is marginally useful as a downlink today (unusable in many locations), and by the time Eagle is launched, and through it's lifetime, will be unusable. Personally, I do not like this decision. I have S-band equipment that I was looking forward to using. Personally, I can live with this decision, and defend it to myself, let alone anyone else, because I am convinced that it is technically sound. As one of you commented this evening, AO-40 wasn't exactly a rock crusher on S-band. It worked, and adequately, at least on CW, but was not great. As I reflect on my personal AO-40 experiences, I now understand that there are 2 reasons for my disappointment. Local noise was one, and transponder distortion was another -- the latter will be corrected by SDX. S-band on AO-40, by necessity not choice, got many of us out of our comfort zones and convinced us that microwaves really aren't that hard. Let's enter the realm of S up and C down with that same realization. REMEMBER THAT AMSAT IS DEVELOPING THE GROUND STATION ALONG WITH THE SPACE SEGMENT. You will not be left on your own to develop ground equipment. You will not be asked to mortgage your house; affordability by the masses is a key component of the design for the entire system. Comparison with AO-51 is an "apples and oranges" thing. The path losses are much different. FM is very unlike CW/SSB or wideband digital modes. Remember that a goal of the Eagle system is that everything is on all the time. No more matrix switches, no more schedules. We need up and downlinks to be useful throughout the entire orbit. Why did we "regress" to U/V? For one reason, many of you asked for it, and some of us worked hard to somehow incorporate that capability in response to member's desires. The foot in the door was the utility of a V-band beacon in case everything else goes sour. The forcing function was as follows. A goal of Eagle has always been some kind of hand-held or jump bag portable ground station capability for entry into the emergency area while the tsunami waters are receeding and the hurricane winds are down to gale force. Many of us thought we could take advantage of the gain in small antennas to do this on the microwaves. Rigorous link analysis led us to the conclusion that the best place to do this is U/V -- both from a RF/DC power perspective, and from a link standpoint. This leads to the digital and "traditiona"l transponder package for U/V, implemented in SDX. Why not also include a (switchable) S-band downlink in parallel with the V-band? Remember, no switches. Also, we run into an antenna space problem. We've already increased the size of the spacecraft from where we started, and for many reasons, do NOT want to build something as large as AO-40. A couple of you have commented this evening that perusing EaglePedia has not revealed the details of the decisions. That is because, while Bob McGwier (N4HY) and I have been working on the report of the meeting, it is not public. We've been working hard on it since June, in and around other AMSAT, ham radio, and life events. Shortly after I push send on this message, I'll begin my final look at that document prior to public release. Before I go spend time with the spousal unit TONIGHT, I will finish it and publish it. I will send an announcement on the amsat-bb that it is public. To read the report, go to the EaglePedia main page, and select project index. From there, select Team and Meetings, and there will be several options, not all public. The San Diego meeting minutes will be obvious and public. Several of you have commented, "If S-band is unusable, why is it flying on P3E?" Fair question, but I can't answer for AMSAT-DL. I DO know that the P3E system design is considerably older and farther along than Eagle. Eagle design decisions were made based on the best information in June of 2006. Aspects of this discussion have been worthy of /dev/null. More aspects of this discussion have raised valid points and reasonable questions, deserving of response, which is why I've been composing this note for the last four hours or so. A few have raised the old allegation of the builders doing what they want, without regard to users needs. This is not true. While the desire to advance the state of the art (part of amateur radio's justification for existence and allocation of valuable spectrum) leads to enthusiasm and study of potentially useful new techniques, this desire had no impact on our analysis-based decisions. We started with requirements and services, and explored what would deliver. I thank all of you for your interest and support. Your Eagle team is working hard to develop a system that will serve our needs, as well as advance the state of the art. As promised, we are making decisions based on sound, peer-reviewed science, not anybody's opinions or desires. Please read the report, study the spreadsheets, download the excel file and play with it. If you can, make your own measurements and put those numbers into the spreadsheet. I think you'll understand how these decisions were reached. After contemplating the report, send me your questions. I'll either respond or forward to he who can best respond. Another fundamental tenet of the Eagle project is openness, so you have a right to a response to a rational question. Please recognize that we're volunteers too, and subject to the realities of day jobs, families, and a real life. Response may not be instantaneous. Thanks again and very 73, Jim James A. Sanford, PE Eagle Project Manager wb4gcs(a)amsat.org

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AMSAT BOD Elections...
by Roger Kolakowski 09 Sep '06

09 Sep '06

I have only one suggestion... Vote with your minds, not your hearts... Roger WA1KAT

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Re: Sband and Eagle: an appeal for a higher level discussion
by Joe Leikhim 09 Sep '06

09 Sep '06

This thread so reminds me of the past pleas for more mode B birds to replace AO-10 and AO-13. The AMSAT board response was that the VHF and UHF bands were getting noisy, illegal VHF and legal UHF interlopers were showing up and for the membership to embrace microwaves and build S band and L band stations. Well I am one who has such a station and while I would love certainly to see mode B, come back, I am also fully equipped to excercise some S and L band experiments. I can understand that many households are polluted with 2.4 GHz toys, mine is. My solution will be to pull the plug on that stuff during operation and to utilize a medium size dish for the downlink (Note: those grid panels can't discriminate as well as a bigger dish, and secondly the IC-970 noise blanker works on some types of S band ISM interference). Please someone tell me that we can work L and S band modes with HEO and linear transponders, I would become so much more interested in the hobby! -- 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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P3E page in english
by dave 09 Sep '06

09 Sep '06

Hello All, Just saw that the p3e-satellite.org page has the english translations working. Now I can start understanding all the references to Euros. One question - on the Join-in page under the "more about the raffle" heading, does it mean that to get any info on the status of P3E I will have to pay for a pixel? 73 de David VK5DG

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C C Rider
by Carl Yaffey 09 Sep '06

09 Sep '06

Will someone please explain what "C C Rider" means for a newbie? Thanks and 73, Carl Carl Yaffey K8NU Banjo, guitar, bass, mandolin lessons. Pro Tools recording studio. carl_yaffeyNO_SPAM(a)yahoo.com. 614 268 6353, Columbus OH http://www.carl-yaffey.com

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dichroic plate
by Geoff 09 Sep '06

09 Sep '06

Hi guys, It appears that future satelllite operations are likely to require operations on multiple microwave bands. Has anyone looked into the design and construction of dichroic plates suitable for amateur band operations? Mode S/X on P3E comes to mind as one place that might need them? For me the mechanical aspects do not present problems. Design does present problems as I do not have the test equipment for ¨cut and try¨ :-( . There are references on descanso.jpl.nasa.gov . 73 de Geoff vk2tfg.

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SuitSat-1 Return
by Frank H. Bauer 09 Sep '06

09 Sep '06

Masa, I sent this to the SAREX reflector, since it is human spaceflight related. But I will post here since the question was raised. 73, Frank, KA3HDO All, On September 7, 2006 at 16:00 GMT, SuitSat-1 re-entered about 1400 km south-southwest of Western Australia. For more details, including the winners of the Chicken Little Contest, please go to: http://www.amsat.org/amsat-new/ariss/suitsatContest.php I want to thank all who made SuitSat-1 the phenomenal event that it was. Your hard work and dedication paid off. In just 3 weeks the SuitSat team developed and delivered a safe satellite system that has gained the confidence of the international space agencies. The web and PR team were able to garner unprecedented press coverage of our ham/educational outreach activity, including over 9 million hits on www.suitsat.org in February. Students around the world had the opportunity to participate in a 7 month "school spacewalk" with the artwork, pictures, signatures and voices on-board. And the "super-sleuth" ham radio operator extraordinaires were able to pull a significant amount of data from the satellite despite of its low signal strength. And my congratulations to the students and adults who won the Chicken Little contest!! Next for SuitSat-1--the commemorative certificates/diplomas. And at the AMSAT-NA symposium/ARISS meeting we will discuss our thoughts and plans for a potential SuitSat-2. Stay tuned! 73, Frank H. Bauer, KA3HDO AMSAT V.P. for Human Spaceflight Programs ARISS International Chairman Message: 4 Date: Sat, 09 Sep 2006 12:19:56 +0900 From: Masahiro Arai <m-arai(a)a.email.ne.jp> Subject: [amsat-bb] SuitSat-1 return To: amsat-bb(a)amsat.org Message-ID: <200609090319.AA01511(a)giga.a.email.ne.jp> Content-Type: text/plain; charset=us-ascii Alititude of SuitSat-1 is decreasing drastically. Its alititude at 1330z 8th Sep was about 150km. SuitSat-1 must have returned the Earth. Many thanks, SuitSat-1!! Masa JN1GKZ Tokyo Japan

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