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

[Freeman Pascal <pascal@xxxxxxxxxx>]

Ooohhh ... this is all very very cool.  The SDR stuff is something I  
have always wanted to play with.  I suppose I'll have to stop waiting  
and do something about it. <grin>

-Freeman, N5FPP

On Jul 23, 2005, at 7:45 PM, 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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> author.
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>

-Freeman

"If you are going through hell, keep going."
     -- Sir Winston Churchill
----
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