On Thu, Feb 23, 2012 at 4:39 AM, Sebastian Döring <sdoer...@rhrk.uni-kl.de>wrote:
> Hello, > > in the context of spectrum sensing in the 2.4 GHz band using a modified > version of the usrp_spectrum_sense.py script, I am having problems with > high latency times. > Since the time for recording samples and all the tuning stuff is supposed > to be much less than what I am currently dealing with (something around > 88ms between two center frequencies), > I was wondering if this might be a problem of some additional calculations > the python script is doing with every message I get from the c++ code. > In particular these calculations contain summing up the vector I get from > the queue of the source and comparing the sum to a previously calculated > threshold wrapped into some if-statements > > Any statements highly appreciated. > > Thanks. > -Sebastian > If it's latency in the flowgraph, you can try and use the new max_noutput_items (pass this value to tb.start(N) or tb.run(N), whichever is being used). The smaller this number, the faster blocks will pass data between eachother, but also the harder your computer is going to have to work to keep up. If you think that the latency is due to Python calculations, you can think about finding a more efficient scipy implementation of the calculations. If one doesn't exist, you can write some C code and look at the f2py program that comes with Python; it's a simpler wrapper generator than SWIG that converts from FORTAN to Python, but I believe it nicely supports C functions as well. Just a couple of thoughts. Tom
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