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Re: LONG and long overdue report



TRULY amazing! I'm sure you've put a lot of blood,
sweat, and tears into it, and I applaud you for doing
this pioneering work.
Well done!
73, Jim  KQ6EA

--- Robert McGwier <rwmcgwier@comcast.net> 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 
> 
=== message truncated ===
----
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