On Sun, May 8, 2011 at 2:03 AM, yulong yang <yyl....@gmail.com> wrote:
> Thanks for reply. > My plan is to extend the usrp_spectrum_sense.py: grab its output data and > let a py script find the best available frequency in the data; then put this > frequency into the usrp2_source block of file transmitter. In such case, my > py script would contain two top_block and the second one, file transmitter, > would run after the first one stops. Is this possible? When you say > threading, do you mean two top_block? > Not really. I was thinking about a separate Python thread function, much like how we did the receiver code in benchmark_rx.py in the digital example. Tom > Speaking of DySPAN, I will look into that. Really thanks. > > > On Sat, May 7, 2011 at 8:55 PM, Tom Rondeau <trondeau1...@gmail.com>wrote: > >> On Fri, May 6, 2011 at 4:34 PM, Yang <yyl....@gmail.com> wrote: >> >>> Hi all, >>> >>> I am recently doing a project on gnu radio and usrp2. My goal is to >>> implement DSA: let Tx sense some bands, choose available one by energy >>> detection, then tune the usrp2 to this frequency and transmit a signal. >>> >>> This might sound quite simple and basic for you, but I find it very hard >>> to get started. I have tried some ways: >>> >>> 1. To write blocks for GRC: >>> I have written a energy detection block find no way to realize the band >>> switching function. Also, my energy detection block can only sense the >>> signal USRP2 received from a fixed frequency (i.e. from usrp2_source block). >>> How could I change the frequency during the detection? I cannot think of a >>> way to make the one-way flow of GRC to do some feedback functions. >>> >>> 2. To extend/modify usrp_spectrum_sense.py: >>> I cannot figure out what is going on in gr_bin_statistic block (even with >>> the detailed explanation from Firas): dose it just copy data from FFT and >>> window block and save them in a .dat file? If it can generate the raw file, >>> what is happening in the main_loop and m.data? Is m.data a file too? >>> >>> Sorry for so much words but I feel I am totally lost in scripts. I am >>> still new to this and I cannot find a place to dive into and get work done. >>> I believe there should be some quite simple and straightforward way to >>> realize DSA. Would anyone point a way for me to go? >>> >>> Any help would be appreciated. Thank you. >>> -- >>> Yang >>> Sent with Sparrow <http://www.sparrowmailapp.com> >>> >> >> >> The IEEE DySPAN conference (which just finished) has had many demos and >> papers about realizing DSA using GNU Radio. If you have access to the IEEE >> proceedings, you should find various references to people who have built GNU >> Radio programs for this purpose, at least as far back as the 2007 >> conference. You might find some useful ideas from any papers published or >> the websites of the demonstrators. >> >> Having done some of this myself, I would say that you could have a thread >> operating in Python that is waiting for a message from a GNU Radio sink >> block. The message would contain some information about the spectrum usage >> that you could then use to retune the USRP sink. So the retuning is done in >> the Python domain and not directly from a GR block. >> >> A more complicated (but possibly more elegant) method would be to use the >> message passing interface. You would set it up so that a work function would >> make some decision on the free channel that would send a message to the USRP >> sink to change frequencies. The most difficult part of this is due to our >> lack of documentation and examples of using the messages. >> >> Tom >> >> >> >> > >
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