July 2007 - Eagle (INACTIVE) - mailman.amsat.org

Receiver Spec vs. ATP, a few Suggestions and a Question or Two
by Juan Rivera 06 Aug '07

06 Aug '07

John, I took a few minutes to look over your new specs and compare them against the Acceptance Test Procedure. I've got a number of tests in the ATP for which there are no specs: * Image rejection * Internally generated spurs * Local oscillator leakage * Input and Output VSWR Items that need to be addressed that aren't in either document: * EMI conducted susceptibility * EMI radiated susceptibility * Short and long-term frequency stability I also take issue with the -60C minimum power-down temperature. I think this is unrealistic just from a CTE mismatch perspective. The reliability of anything subjected to that wide a temperature spread is going to suffer. A way must be found to raise that temperature. I have a few thoughts... The CAN-Do switching step-down converter is only supplying 11 milliamps. If we take a slight efficiency hit we could just go to a simple linear regulator and completely eliminate the radiated and conducted EMI emission problem from CAN-do. That eases the EMI filtering and shielding requirements for every single payload. That seems like a good trade-off to me. Rather than worry about trying to conduct heat through a PCB why not just go to externally mounted regulators for the CAN-Do and the Receiver right on the case itself. We're not that pressed for space. That eases the heat sink and the associated thermal gap filler issues. EMI will still be an issue, but only for external sources instead of one that is inside the enclosure itself. That strikes me as a huge bonus. Why not design a single-sided PCB with the regulators hanging over the edge and the whole assembly, PCB and regulators, mounted directly to the enclosure. Stick it in with the CAN-Do module in a separate cell. Filter all the signal and power through the common bulkhead. I'm also curious as to why you are specifying two different types of SMA connectors. 73, Juan - WA6HTP

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This weekend at Central States VHF Society
by Tom Clark, K3IO 02 Aug '07

02 Aug '07

This year's CSVHFS meeting wound up tonite in San Antonio. Among the many AMSAT folks in attendance were W4MO, W7LB, W5IU, W3XO, N4HY, K5SDR, W5SXD, N6TX, KL7UW and K3IO. There were no satellite specific papers presented this year, but the world of DSP and SDR was very much present. K5SDR presented his new SDR5000 radio. KL7UW (with the SDR-IQ) and W5LUA (with the Softrock-40) reported on the use of SDR receivers for various VHF/UHF/Microwave tasks. AMSAT highlights of the meeting came at Saturday Night's banquet. K3IO accepted a financial contribution from CSVHFS for AMSAT. And then the crowning glory: Bob McGwier, N4HY was presented the 2007 John Chambers Memorial Award for technical achievement, recognizing his many SDR and AMSAT activities. Bob joins previous AMSAT Chambers Award recipients W0LER, W0PN, W3GEY & K3IO. Congratulations to Bob -- 73 de Tom, K3IO

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Re: N4HY wins prestigious award
by Robert McGwier 29 Jul '07

29 Jul '07

Thanks Dale, Tom, and others. I have had great partners in all of my work. I am grateful for all of the ideas, support, trust, complaints, advice etc. that have flown freely from the SDR,Flex groups, TAPR, ARRL, and of course, AMSAT. It has been amazing fun to try out new ideas here and to work with Frank, Eric, and many others on our joint endeavors. There are too many people in AMSAT to thank but one must be singled out. Tom Clark talked me into doing technical work in AMSAT when I was still in college and later talked me into doing the DSP project with TAPR and AMSAT. That advice and encouragement had a tremendous impact on my life, defining its trajectory almost completely. My close relationship with Tom has gone on for over 25 years. Tom often does not seem to see that of all his contributions, the most important of all by far is the impact he has had on others through his friendship, mentoring, and leadership. In my mind, it is the one of the most accomplished lives in amateur radio and beyond if you completely subtract all of his technical work. Tom talked me into joining Central States who gave me the award. My wife and I love it so much we go every year not unlike most of its members. Dale, your friend was the runner up in the big CSVHFS operating award again with an eye toward going for first. I know you are proud of that friendship. I do not covet awards and I certainly don't seek them but the John Chambers award is one I am extremely proud to have as all of my engineering mentors in amateur radio have received it including, but not limited to, Tom and Jan King. This was a complete shock. 73's Bob Dale Boresz wrote: > Congratulations on the award Bob - and thanks for your continuing work > to advance the state of the art of radio communications. > > Great times for amateur radio. > > Dale > WA8SRA > -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson

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Re: This weekend at Central States VHF Society
by wb4gcs＠wb4gcs.org 29 Jul '07

29 Jul '07

CONGRATULATIONS BOB!!!!!!! Very 73, Jim wb4gcs(a)amsat.org This year's CSVHFS meeting wound up tonite in San Antonio. Among the many AMSAT folks in attendance were W4MO, W7LB, W5IU, W3XO, N4HY, K5SDR, W5SXD, N6TX, KL7UW and K3IO. There were no satellite specific papers presented this year, but the world of DSP and SDR was very much present. K5SDR presented his new SDR5000 radio. KL7UW (with the SDR-IQ) and W5LUA (with the Softrock-40) reported on the use of SDR receivers for various VHF/UHF/Microwave tasks. AMSAT highlights of the meeting came at Saturday Night's banquet. K3IO accepted a financial contribution from CSVHFS for AMSAT. And then the crowning glory: Bob McGwier, N4HY was presented the 2007 John Chambers Memorial Award for technical achievement, recognizing his many SDR and AMSAT activities. Bob joins previous AMSAT Chambers Award recipients W0LER, W0PN, W3GEY & K3IO. Congratulations to Bob -- 73 de Tom, K3IO _______________________________________________ Via the Eagle mailing list courtesy of AMSAT-NA Eagle(a)amsat.org http://amsat.org/mailman/listinfo/eagle

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CAN-Do 3-second Glitches
by Juan Rivera 28 Jul '07

28 Jul '07

Stephen, I've mentioned this to you before and you've been kind enough to try to explain it to me several times, but I wanted to document these CAN-Do three-second glitches for posterity. After you look over my log and listen to the recording please feel free to add to my log. Just send me your comments and I'll include them. Here's the link --> http://www.juanr.com/pages/hobbies/ham_radio/Eagle/3-Second_Glitches.htm 73, Juan

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DC Input Test
by Juan Rivera 28 Jul '07

28 Jul '07

John, I'm in the process of reconciling your requirements document with the ATP. The first test in the ATP is a receiver power supply test. Requirement Actual Result Minimum voltage with no loss of signal level 10.8 10.35V 312.1 mA Pass Minimum voltage with 1 dB loss of signal No spec 10.14 N/A Maximum voltage 16.8 16.8V 230.7 mA Pass Juan

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[Fwd: HFSS Training, Burlington MA, August 2-3]
by Tom Clark, K3IO 26 Jul '07

26 Jul '07

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Status update
by Jim Sanford 24 Jul '07

24 Jul '07

Team: It's time for me to draft the next Journal article. Please send me your update by Wed, 1 August. If you have no progress to report, please send me that. (And let me know what's coming in the near future.) Thanks & 73, Jim wb4gcs(a)amsat.org

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70 cm Passband at -1 dB and -60 dB
by Juan Rivera 24 Jul '07

24 Jul '07

All, I re-ran the -1 dB passband test of the 70 cm receiver for my presentation. Here's another look at a 500 kHz span at 0.5 dB/Div: Here's a look at the -60 dB passband with a 2 MHz span and 5 dB/div. I increased the input Level to get the skirts out of the noise. It's 1.248 MHz wide at -60 dBc. Juan - WA6HTP

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A new opportunity (Phase 4 lite?)
by Robert McGwier 23 Jul '07

23 Jul '07

In the last few weeks we have been presented with a new opportunity to launch RF platforms into space. This note will necessarily be cautious because we do not wish to do or say anything that will throw a monkey wrench into the works. More specific details than are given here will come from one voice, and that is from Rick. This is a major development. One which will refocus some of the energy of the organization should it come to pass. That said, no one in management has proposed we stop Eagle and Jim Sanford will remain its project manager irrespective of what goes forward on the new project because we are still looking for rides for it. The following is adapted from Rick's note to the board of directors, with comments from me (and edits). We are being asked to propose that we ride on someone else's satellite with our RF gear and antennas. The primary is not a small satellite. It will go to geosynchronous orbit. There are MULTIPLE rides being discussed but we have to get our act together for round one. The planned lifetime of the large satellite is over a decade and they have a track record of exceeding it. At the beginning of life it produces 1 kw of excess power and we are trying to ask for at least 1/3 of that because at the end of life, after years of solar degradation, that is what the primary expects it to produce as excess power. They do station keeping to maintain their subsatellite point. They provide the ride. Thus, we do not need a motor, fuel tanks, hydrogen bottles, propellant flow assemblies, or liquid ignition units. They provide the electricity, thus we do not need solar cells or a battery. We will not need an attitude control system at all or even attitude sensors except for "gee whiz" like cameras or experiments. They could easily provide us about as much space and mass as the Eagle would have consumed, BUT WE DO NOT NEED IT. Rick suggested to them that we would probably need as much antenna space as we have proposed for Eagle, and they did not blink. Mechanical constraints (moment of inertia ratios) allowing for a motor are completely out of the picture. We will be rigidly mounted to their frame and they do the work. They will be asked to provide some thermal control for our RF modules, which will sit on the Nadir pointing side of their spacecraft, which is 3 axis stabilized, and will of course be subjected to hours in the sun and hours in the dark. A careful thermal design is required. We will never need to point another antenna on the ground after the very first time should their payload behave. We will not need to despin a phased array at 3 rpm. WE WILL need a phased array but it will be adjusted in tiny increments on a daily basis at most. No more spin modulation unless there is some failure on their bird. We need our very high efficiency power amplifiers, both the proposed linear and hard limiting design to be, as much as possible, producers of RF and not heat. They are offering this opportunity because they have discovered that if a goodly portion of the heat that is dumped from their solar arrays at the beginning of life is consumed in RF, light, etc., it saves them a considerable number of resources. This was one clever study by an in house engineer. They have been given some basic technical information on our proposed payload. We, AMSAT, must get together now and provided them with real answers on our proposed payload in a formal written proposal, but they were given these rough estimates. We need to provide the follwing which includes but is not limited to: 1) Size & Mass [less than 50kg, probably closer to 20kg, no batteries, ] Antenna Configuration (space required) [they were told the same as Eagle, a 60cm per side hexagon or some equivalent] Frankly, it needs no symmetry at all. It can be completely determined by the needs of the antennas and the envelope restricting us. 2) Given that, there is no need for a very thick spacecraft since it has NOTHING in it but RF modules and computer(s). 3) Power requirements [they were told about 300 Watts] 4) Efficiency (how much power becomes heat) [we agreed to choose 0% to start thermal design] (sic, from Rick. I don't understand what needs to be calculated if we agree that we produce 300w of heat, then our body will quickly rise to a very high temperature and melt. I think they want to upper bound the thermal control needed for us. ;-) . ) 5) Need for some of their on board resources to be specified and more details follow after our study. 6) They must be told a REALISTIC schedule that we can meet. That will determine what launches will be available to us and where the multiple payloads will be placed. We do know their power bus is many times our planned voltage, and we need to decide if we or they build the power converter. This is pretty obvious because they don't want to power TWT's, etc. from 5 or 14V!!! If we do multiple payloads with them, as is currently proposed, they would consider providing a "LAN" for us to communicate between satellites to our payloads (think direct, bird to bird interlinking). If the design study says we will not impact them greatly, they can provide us this link. For Eagle, we have planned to use 3400-3410 MHz for Earth->Space and 5830-5850 MHz for Space->Earth. It may be necessary to switch these to be compatible with their transponders which are on nearly identical frequencies BUT IN THE OPPOSITE DIRECTION. We don't want to transmit near their receive frequencies. This raises a serious problem as Region 1 does not permit us to radiate signals from the satellite in the 3400-3410 MHz band if they can see it. So it is clear, I will need to call engineering meetings, and more than one, in the next couple of months. We are prepared to spend the money on these meetings and bet this will be pulled off. If it looks like we really will close this deal (as in signing an MOU) then we will definitely bet the farm on it. Right now, we probably should think we are basing the payloads initially on what has been thought of for Eagle and we need to rethink this because one thing should be crystal clear. THESE ARE NOT ADEQUATE. Think about what it will mean to have a very loud transmitter, either analog or digital, available 7/24/365.25 at the same spot in the sky. We do not have sufficient capacity in our current design, period. We would not want to do the SMS text messaging in the linear transponder, but would likely move it back to Microwave for example. This relieves the phase noise demands on the system for SMS (maybe not other considerations TBD). Also, the user antennas on the ground are fixed. We need some redesign starting from our basic payloads and then building them out to meet what capacity we think we can support but this will be the first time we have ever spent all of our power on the RF and very little on anything else! I hope you can see that we must be both bold and professional with a dash of caution. A dash only because the probable time schedule will not allow us to pontificate for half a decade. If we pull this off, there is very little doubt in my mind that this will change not only AMSAT, but amateur radio in general, and if we do our job well, in a big way. We must thank Lee McLamb profusely for finding out this opportunity was becoming available. Special circumstances allowed us, following his notice to us, to move VERY quickly to "go in at the top of the organization". That was done (MAN do I love low friends in high places and in this case, at the very top). More details will follow as the okay comes from Rick. Please refrain from speculation or much gossip. I know I would be heart broken if the wrong leak or wrong public statement caused us to lose this major opportunity. I will not be entertaining a thousand questions but I do want everyone to think about the redesign of the payloads carefully to support a geosynchronous bird. 73's Bob N4HY -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you're going to be crazy, you have to get paid for it or else you're going to be locked up." Hunter S. Thompson

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