Tom Rondeau wrote: > On Thu, Mar 4, 2010 at 10:28 AM, Mattias Kjellsson <m...@kth.se> wrote: > >> Eric Blossom wrote: >> >>> I assume that you mean 1 byte per symbol. >>> I suggest that you create *_ci and *_ii versions that handle 32-bits. >>> >>> Eric >>> >> You are correct, one byte per symbol. Or one symbol per byte, whichever >> way one wants to look at it. >> To clarify what the custom block does is that it takes K bytes with 1 >> significant bit (in lsb, from a glfsr or similar) and turns it into 1 >> byte with K significant bits. Then it's just to feed these new, "packed" >> (is this the word for it?), bytes into the chunks_to_symbols_bc- block, >> producing one symbol for every byte. >> >> Is this really stupid, or has it just not been done yet? I assume that >> there are more people working with more signal- points than two in their >> constellations. But at the same time it seems like I'm wasting a lot of >> resources on copying bytes with only two or three (qpsk, qam16) >> significant bits in them... >> >> >> //Mattias >> > > Have you looked at > gnuradio-core/src/python/gnuradio/blks2impl/dqpsk.py (and qam8, qam16, > qam64, and qam256.py)? They handle the modulation and demodulation > parts of the TX and RX. We don't have a good synchronization scheme, > but I think these do what you want. > > Tom > I know of them, and have looked at them, but nothing more. Since I don't speak python very well, I try to do everything in c++.
I have tried to use pilots mixed in every few data- symbols and compensate the data- symbols using these known symbols. I'm getting kind of good results, although I think the custom early/late gate sampler I wrote has a settling time way to long (between 900 and 3000 symbols depending on which constants I put in). I'll try to rewrite the M&M- sync- block to utilize the slicer_45deg(), and see what results I get with that. From what I can tell from the paper pointed to by the header- file, the optimized M&M- loop should be able to handle at least QPSK, and have a way shorter settling time than 900 symbols. I think the pilot- compensation code should still work and compensate any screw to the constellation. I'm getting all exited just writing about it ;) I'll let you know how it goes. //Mattias _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
