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

70 cm Eagle Receiver - Final Spur Report (at least for today...)
by Juan Rivera 18 Jun '07

18 Jun '07

All, I've completed my testing and analysis of the spurs that appeared in the IF output of the 70 cm Eagle Receiver prototype. I believe I know the source and the cause of all of them and how they can be eliminated or rendered harmless. Click HERE <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/Spur_Suppression.htm> to read my report. 73, Juan WA6HTP

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CAN-Do noise problem is proving to be a difficult one to fix
by Juan Rivera 18 Jun '07

18 Jun '07

All, Please see my write-up here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo ting.htm> . The CAN-Do noise is not lending itself to an easy cure. I think this whole subject of RFI/EMI needs to be looked at closely. Every payload will be affected by noise on its inputs and can affect other payloads by creating noise that is propagated back out from within its module chassis. With the current scheme, of having a CAN-Do module located in the same case as the main payload, there are several issues that need immediate attention: 1) The CAN-Do module provides dirty power - both the +13 VDC output and the ground are noisy 2) The CAN-Do's switching power supply inductor, L3, radiates noise that can affect sensitive circuits several inches away. Both of these factors are adversely impacting the 70 cm breadboard receiver in the form of 5 kHz spurs on the IF output. As I mentions earlier, Rather than work to clean up the CAN-Do module immediately, we should focus on making the receiver function In the presence of this noise. This approach will result in a more robust design. The CAN-Do module needs to be cleaned up, but for now it acts as a great real-world noise generator. I'm currently out of ideas. I'd like to hear what you all have to say. 73, Juan WA6HTP

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Preliminary CAN-Do EMI Findings and Suggestions to Mitigate in the 70 cm Receiver
by Juan Rivera 18 Jun '07

18 Jun '07

All, I've completed a preliminary evaluation of the CAN-Do RFI problem. Please see my log for details by clicking here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo ting.htm> . Preliminary Findings... 1. The spurs seen in the receiver IF enter the receiver in two ways o As radiation from the CAN-Do inductor o Via CAN-Do module switched +14 VDC power on pins 39 and 40 2. I/O line filtering appears to be unnecessary 3. The switched power from the CAN-Do module pins 39 and 40 must be filtered 4. The CAN-Do module will either have to be kept physically separated from any sensitive components, redesigned, shielded or a combination of the three. 5. Moving the Can-Do module 2-1/4" forward of its normal location on the receiver PCB lowers the EMI level below the noise floor. Suggestions... * Create a full size PCB for the next generation receiver and shift the RF components to the back of the board (away from the CAN-Do module.) * Add DC input filtering to the receiver 73, Juan WA6HTP

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AO-51 received signal strength survey
by Andrew Glasbrenner 17 Jun '07

17 Jun '07

Gentlemen, Gould and I are planning on running a survey with the SQRX on AO-51 during the V/S session at the end of the month. In the past I have created signal strength maps for the earth that show the RF levels seen at the satellite. Would this be useful for any planning for Eagle or P3E? We were thinking we could listen at L band or in the proposed Mode B uplink window. 73, Drew KO4MA

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Power Grounds
by Bill Tynan 17 Jun '07

17 Jun '07

Juan Rivers wrote in part: I've been thinking about DC power distribution in general. Can someone explain the plan for Eagle to me? In aircraft, at least in the one I am familiar with, they do not use the chassis as a return. All DC power is treated the same way as AC power and distributed from a common point as a twisted pair to minimize common mode noise. Great care is taken to eliminate ground loops by insuring that the ground returns are back through the twisted pair to the source and not through a sneak path to the frame. I agree. This is the way it was in the missile business when I worked on Tomahawk, Standard Missile and Talos from the 50s thru 1988. 73, Bill Tynan, W3XO Now back on the Eagle list. Thanks Jim & Paul.

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Cool Model
by Dick Jansson-rr 17 Jun '07

17 Jun '07

Bob: I have done some experimental work with a satellite in the eclipse mode of cooling using the currently active P3E files. The results are a little bit tongue in cheek, but I shall report them nonetheless as these results may help the Eagle team. The reason for my caution is that some of the results are a bit uncertain in my mind, but useful to others. The P3E model had the sun "turned off" for a 2 hour period and pretty well powered down save for a command receiver, a beacon transmitter, and the IHU. The geometry of these modules, and their placement in the P3E spaceframe, bears no resemblance to the Eagle modules, which certainly is a point of caution. The results of these analyses, one with propellant (a very substantial thermal mass) and one without the propellant. I shall report two temperatures, one for the model with propellant and the other without the propellant. Solar panels really get chilly, as expected, as do the internal equipment panels. So here goes, all temperatures in degrees Celsius: Solar Panels: -45.7/-51.6 Equipment Panels : -22.6/-29.5 Top & Bottom Panels: -30.0/-36.6 Central Cylinder: -10.7/-26.7 L Receiver: 0.0/-2.0 U-V Transmitter: -12.2/-14.2 I shall not report the IHU temperatures as I don't believe them and have not yet been able to understand them. The LRx was dissipating 2.0W while mounted on top of a box dissipating 0.4W, the U-V Tx dissipating only 2.0W, with a total dissipation of only 6.2W. The power dissipation is modest but so to is the P3E battery energy. What these numbers tell me is that there is hope that the Eagle equipment would not even see -20°C, but I feel that -30°C should be used as a bottom limit number. This caution is based on the fact that the Eagle geometry is not nearly as closely packed as is P3E. Dick Jansson, KD1K <mailto:[email protected]> kd1k(a)amsat.org <mailto:[email protected]> kd1k(a)arrl.net ---------------------------

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70 cm Receiver IF Spurs - Problem Solved
by Juan Rivera 16 Jun '07

16 Jun '07

All, The 70 cm Receiver spur problem has been solved. Click here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo ting.htm> for details. 73, Juan WA6HTP

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latest 70 cm Receiver test results
by Juan Rivera 15 Jun '07

15 Jun '07

All, I've posted my latest 70 cm Receiver test results here <http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo ting.htm> . I'd been guilty of tunnel vision. See my log for new details. 73, Juan WA6HTP

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Preliminary Findings - CAN-Do Module Noise
by Juan Rivera 14 Jun '07

14 Jun '07

All, Please see the usual location for my preliminary CAN-Do noise test results - Look for CAN-Do Noise Troubleshooting in the Eagle Receiver page, or go to my web at http://www.juanr.com and drill down in the menu, through ham radio, to AMSAT Eagle, to CAN-Do Noise Troubleshooting. It's about 100F in my shack at the moment so I'll trust you to find the preliminary report there so I can clear out of here and cool off. I intend to dig into this in much more detail once it cools off... 73, Juan WA6HTP

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Apologies, status
by Robert McGwier 13 Jun '07

13 Jun '07

Until a) The Flex 5000 comes out, b) June 27 arrives and my summer project starts at work, c) Linux version of Tac32 works and clock steering algorithms in CNS II clocks are perfected for my work needs I do not have a life. I am going to bed at 3 AM and waking at 6 AM and commuting to Austin every weekend. Do not expect much from me, i.e., I do not have time for hour+ long TS meetings until probably the middle of July. At that time, I want to make a major push on getting the ACP and Linear experiments revisited after a year's work and analysis. I suggest we plan on some activity associated with that. The critical mass right now is in California and I have the approval to get some space out there for RF congregation that I need to close the loop on when the dust settles on some of these activities. I expect to attend a Suitsat2 meeting for a day in early July but there will be little else from me for a month. The SDX is working well in software. Howard is doing a great job. Lyle wants to begin work on the SDX hardware by fall. Marc Franco has his paper published and we can begin implementation of the VHF transmitter and the EER part of the SDX in earnest as soon as we have an exemplar from Marc or get his designs and recreate them. Next, we paid the huge freight to the State Department for our ITAR issues after we listened to Harold Price, our attorney's, etc. For those who are not U.S. citizens and members of this group, you will, as individuals or through sister societies, need to enter into Technical Assistance Agreements with us, even if you are Canadian, British, German, etc. (All the usual suspects). This is not as painful as it may seem since we are going to do the boiler plate but it must be done. Bob -- 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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