Re: [amsat-bb] LONG and long overdue report

[Scott Townley <nx7u@xxxxxxxx>]

all I can manage is...wow...wow...wwooooooooooowwwwwwwwwww thanks for the 
scoop!


At 18:45 2005-07-23, Robert McGwier wrote:
>Apologies to my colleagues and expect to see much more from all the 
>participants in upcoming journals and meetings.
>*
>
>There has been work going on that has not been adequately described 
>anywhere and I take the blame for that.   I have been spending engineering 
>money on your behalf.  Let me summarize it for you and apologize for the 
>length of this note.  If I include technical details here, it would be 
>much too long and articles for the journal will follow this short report. 
>Frank Brickle, AB2KT, and I have been involved with Flex Radio doing the 
>digital signal processing code for the SDR-1000 for almost 2 years.  Frank 
>and I are doing this as volunteers for Flex and I am doing it 
>professionally for my employer who has myriad uses for this technology and 
>software.  Frank and I  have no formal relationship with Flex and our work 
>has been entirely voluntary.  We have insisted that all work proceed under 
>the GPL,  but we did not have to work hard at this insistence since 
>Gerald, K5SDR,  is a clear believer.  Please visit
>
>http://www.flex-radio.com
>
>and
>
>http://dttsp.sourceforge.net
>
>for full details and the code.
>
>When asked to join the Eagle design conference, I attended with the idea 
>that I would give a few ideas, listen to a few ideas, get some ideas, and 
>then go home and go back to sleep.   I should know myself better by 
>now.   It became clear that the same old arguments would be presented 
>stating we simply cannot live without Mode B.   It was clear that we would 
>have to give up significant territory in the spacecraft and power budget 
>for anything that would interest me personally.   I wanted to jump all 
>over CC Rider, which is a 5650 MHz uplink and 5850 MHz downlink 
>transponder.  This was another terrific Tom Clark (W3IWI) idea and it 
>captured my interest.
>
>ftp://ftp.cnssys.com/pub/amsat/cc_amsat.pdf
>
>and
>
>ftp://ftp.cnssys.com/pub/amsat/cc-revisited.pdf
>
>It would give us our first satellite presence in these two bands and would 
>provide us with some interesting technology and engineering and 
>theoretical development issues to resolve.   It would be a new educational 
>prod to our users to learn and do something new.  So I opened my mouth and 
>said that I would be more than happy to "write" a software defined 
>transponder for all of the normal "narrow band" transponders if and only 
>if,  CC Rider would be given 100% access to the power budget and always 
>operational when it could be aimed at the earth.  I would never consider 
>supporting a RUDAK type mission where lots of work would be done and 
>almost nothing ever done to use it.  In fact, I claimed that all 
>transponders could be, and likely should be, software defined radios.  The 
>spacecraft mechanical design and analysis shone at this meeting gave 
>sufficient power budget to meet the design goal of 100% Mode B or Mode LS 
>and 100% CC Rider simultaneously.  We would have to constrain the CC Rider 
>bandwidth to do all we wanted to do and allow small antennas on the ground 
>but it would still be very interesting indeed.
>
>That landed me in hot water.  The group put me in charge of the 
>transponders period.  This has begun to bear fruit.  Frank and I have been 
>building a working 48 Khz transponder for Mode  B and Mode A.   It is done 
>using SDR-1000's and transverters and a Mini-ITX computer.  THIS IS A 
>PROTOTYPE.   However, what can be done is pretty spectacular.
>Swapping between Mode's A and B is quite easy with this equipment.  That 
>said,  this is not your father's Mode B and Mode A. We can have a three FM 
>receivers and transmitters on one side of the beacon (which is in the 
>center) and fully linear above the beacon.   We implement Leila in DSP and 
>even loud AMSAT lovers from southern Europe could not be louder than the 
>beacon by more than 3 dB no matter how many megawatts EIRP they 
>transmit.   Even better, pileup participants will be shoved down to the 
>noise floor where none of the emitters would be audible and good behavior 
>would be strictly enforced since the sum of the people on the same 
>frequency will be limited to 3 dB above the beacon!
>
>If we got tired of this configuration, we could turn it into several 
>digital transponders or FILL IN THE BLANK, by simply changing the DSP 
>configuration.  Frank and I have made that very easy to do in our 
>system.   We will likely have to do some serious experimentation with 
>processors to find the suitable one to carry the load and not need half 
>the power budget but it is a great challenge and one I relish.  What was 
>it Tom and I used to say? "It's only software!"  Indeed it is and the 
>nicest thing is, most of the software already exists (for a change). This 
>MODE B AND MODE A TRANSPONDER WILL BE DEMONSTRATED AT THE ANNUAL MEETING 
>IN LOUISIANA.  Once we decide on the politics and legalities of where to 
>place the transmitter and receiver bands, we will announce what equipment 
>to bring.  Please bring your G3RUH PSK demodulator and decoder software to 
>see the M blocks coming your way.
>
>Recently, Frank and I joined the Gnu Radio "family" and I own (and so does 
>AMSAT) the Gnu Radio project's Universal Software Radio Peripheral (USRP).
>
>http://www.gnu.org/software/gnuradio/
>
>and
>
>http://www.ettus.com/
>
>John Stephensen,  KD6OZH, has kindly donated two of his DCP-1's and we are 
>building them up to use as well for our experiments.  With his OFDM modem, 
>we can even start transmitting the digital signals of interest to us in 
>this transponder or utilize that structure in a modified way for the 
>ground stations.  These units
>
>http://www.arrl.org/tis/info/pdf/020910qex041.pdf
>
>These two units, USRP and DCP-1, are FPGA based engines.  We are planning 
>on running several design experiments on these units.   Matt Ettus, N2JMI 
>has given us a receiver for L band and will be doing the same for an S 
>band transmitter.  We can program the unit, using the same prototyping 
>system that will run the Mode B transponder prototype, to do a few hundred 
>KHz wide LS transponder.  If we get the parts and can get some minor 
>control going, it will be very easy to run a transponder on the 
>USRP.  THIS IS A PROTOTYPING EXPERIMENT. Again, we are going to have to 
>carefully size our needs to have a possible power budget for the 
>processing needed to put this transponder on the air as the USRP in its 
>current form, takes 10 watts to do the job. For the initial CC Rider 
>concept, we have a difficult task.  We are proposing to use patch antennas 
>with several small transmitters and preamps at the antenna and phasing 
>these to be Nadir pointing.    The USRP is uniquely qualified to enable 
>these experiments.  It has four receiver and four transmitter ports.  We 
>could do our phasing experiments using these ports.  If this does not work 
>out,  and it is the riskiest part of the CC Rider concept, we can fall 
>back to traditional gain antennas but it will limit the utility of this 
>transponder to near-apogee and when nadir pointing. Tom Clark found an 
>interesting part for 5 Ghz that looks promising.  It is the Hittite 1 watt 
>linear amplifier (HCM408LP3) and we have two evaluation modules to get a 
>clear idea of the operational characteristics at differing power 
>levels.  This would be important if we wish to allow for side lobe 
>tapering by use of a scaling on some of the elements in the phased array.
>
>Frank, Tom Clark, Rick Hambly, and I have been having regular meetings in 
>Rick's lab.  These experiments are proceeding and with some of these 
>results, we will be calling together several people to try to get them to 
>participate in our ambitious projects.
>
>Expect to hear more and see more in the journal as we continue this work 
>and we pick up the pace in anticipation of the annual meeting.
>
>
>A new IHU for Phase 3 E and AMSAT Eagle
>
>Recently we have begun preparing the new integrated housekeeping unit for 
>Phase 3E and AMSAT Eagle.  Lyle Johnson and Chuck Green have done a great 
>job in designing and getting it getting it ready for testing and ready to 
>accept IPS, the standard spacecraft operating system originated by Karl 
>Meinzer, DJ4ZC.  Karl was heavily involved in the design of the watchdog 
>system and the overall architecture.  He has asked that we work on a 
>software defined receiver utilizing a very powerful forward error 
>correcting code and that it be run on the IHU-3.  If this is successful 
>and proves reliable on P3E, it will be the primary link to the ambitious 
>P5A Mars mission Karl is leading.
>
>Yesterday the test code suite came up and ran on the IHU.  Immediately 
>after finalizing that and getting it to Stacey Mills, who will be doing 
>radiation testing for us, we will begin putting IPS on it.  Expect to see 
>the development model running this code at the annual meeting and expect 
>to see an article by several folks with Lyle and Chuck taking the lead on that.
>
>Thank you for reading and for your continued support of AMSAT.
>
>73's
>Bob
>N4HY
>*
>----
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