[hpsdr] HPSDR Project Proposal - Spread Spectrum

[Kirk Weedman]

On this note.  Would anyone be interested in learning Verilog via an 
internet class?  I have taught courses in Verilog a few times, so I 
could use my powerpoint slides.   I usually teach a 5 day all day 
class/lab so that would be at least 20 hours worth of lecture unless I 
change it a bit.  Next hurdle for me would be how can I present a 
"webinar" type class on the internet and what time of day to do it?  
Havent looked to see what tools there are for doing this.  Anyone 
interested?  I am currently working on the Ozy, Janus, Mercury and 
Penelope code under Phil Harmans direction and would be glad for others 
to understand it when I'm done.

Kirk Weedman  KD7IRS

Cliff Chism wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> A Project Proposal For Calypso - The Spread Spectrum Transceiver
>
> I have recently been investigating FPGA and CPLD programming. As is usual,
> it is difficult to really get into such an endeavour, without first having a
> goal. Of course, understanding the HPSDR system, as it currently stands, is
> one very good reason. But, that is more a matter of comprehending something
> that has already been done. I wanted a project that would advance the radio
> art. The one I came up with will be a major endeavour not only with respect
> to programming, but also in RF theory. As the idea currently stands, it is
> well beyond anything I've ever tried before (that's part of the challenge)
> and in consultation with Phil Harman VK6APH, decided that the idea should be
> presented to the members of the HPSDR list, to see if there might be group
> interest in such an undertaking. I am almost positive that it can be done.
> Whether or not, I am personally capable of such a task, remains to be seen.
> But, with the help of the more than capable members of this group, I believe
> it can be achieved.
>
> Spread Spectrum has the distinction of being one of the few areas of amateur
> communication that has not been embraced by the community, at large. A few
> have made notable forays into the field (AMRAD performed a large number of
> experiments in the 80's and 90's, resulting in the publication of the ARRL
> Spread Spectrum Sourcebook, no longer being published, but still an
> excellent, if dated reference). But, it has largely languished in obscurity,
> I think, due mainly to its inherent complexity. If the means might be
> perfected, or at the least made usable, the benefits to the amateur bands
> could be staggering, especially considering the congestion that exists
> today, sure to only increase in the coming years.
>
> This idea is in its infancy. As I currently understand the situation, the
> main areas of difficulty lie in acquisition and synchronization of the SS
> signals. In order to break the problem down into individual goals, I have
> decided to first concentrate on generating the pseudorandom noise sequence
> via an FPGA algorithm. Step 2 would be to get a hardwired transmitter and
> receiver to sync on the generated signal, and develop a method of forward
> error correction. Step 3, Acquisition, appears to be the most difficult part
> of the problem. I propose that an interim solution might be to use an
> automated and conventional narrowband direct link between the transceivers,
> synchronized via GPS timecode (ala Gibraltar, which I am told, is
> progressing) and able to pass correction data between them, to establish the
> parameters of the link and the PN sequence key, and then to quickly switch
> to spread spectrum. This might be construed as cheating, but provides us
> with a usable SS system, where experimentation might continue, in order to
> develop a method where acquisition is possible "on the fly".
>
> In very fruitful discussions with Phil Harman VK6APH, he suggested
> using a short PN sequence for initial synchronization and programming
> the FPGA to try all possible keys at once, in parallel. This could lead to
> extremely fast synchronization of the signals, and cut
> down on the "waiting period". Then, a longer key could be exchanged via the
> established link, leading to an even more efficient use of bandwidth.
>
> So, assuming that the idea is intriguing to a number of members, I am
> proposing a transceiver, using Direct Sequence or Frequency Hopping Spread
> Spectrum technology. Just about every other facet is subject to negotiation,
> pending further review of technological and legal issues. The FCC has seen
> fit to encourage experimentation on SS, but at the same time, has put a
> myriad of obstacles in the way of experimentation. It remains to be seen how
> much can be accomplished within those guidelines, and how amenable they
> might be to relaxation of the rules, in the face of a workable and efficient
> system. They have permitted variations, in the form of STA's to a few
> experimenters, in the past.
>
> For the time being, I am planning on using Ozy as a development platform for
> the FPGA work, to establish the basic functions, and "doability" of the
> idea. I will also have access to a Digilent Nexsys2 Spartan 3e FPGA
> development
> board (Thanks for the head's up, Phil C.) and Lyle's KK7P DSP module, for
> further experimentation.
>
> Please think of this proposal as a sounding board, to the group, to get a
> sense of whether the interest might be there, for a project of this type.
> Any constructive comments would be most welcome. I believe that the project
> is doable. I believe that it will be a great challenge (especially for me,
> personally). And, I believe that, if successful, it would lead to a great
> advancement of the radio art.
>
> 73,
>
> Cliff Chism - KE5FJV
>
>
> _______________________________________________
> HPSDR Discussion List
> To post msg: hpsdr at hpsdr.org
> Subscription help: http://lists.hpsdr.org/listinfo.cgi/hpsdr-hpsdr.org
> HPSDR web page: http://hpsdr.org
> Archives: http://lists.hpsdr.org/pipermail/hpsdr-hpsdr.org/
>
>
>   

 1233021389.0