On 03/05/2012 01:58 PM, labarowski wrote: > > > Josh Blum-3 wrote: >> >> >>> - dont use a throttle, the usrp sink *is* back-pressuring the stream >> >>> - use this new signal source on my new_blocks or next branch, its much >>> much faster: >> >>> git://gnuradio.org/jblum.git >> >>> http://gnuradio.org/cgit/jblum.git/tree/gr-blocks/lib/signal_source.cc?h=new_blocks >> >> Didn't realize that a throttle was unnecessary with the usrp. Thanks for >> pointing that out. I see that you have a lot of other blocks in your >> repository as well. Do these have any advantage to the ones included with >> gnuradio? >> >>
They all add performance, utility, also support for fixed point IO. >> >>> 50 Msps is serious amount of data to push through your computer. More >>> than a feeling, even the most serious computers can easily have a >>> bottleneck. I suspect that the gnuradio core signal source cannot >>> sustain 50Msps in 1 thread/1 work function. >> >> Makes sense. I would assume that, as long as I'm using grc at least, I'm >> limited to one thread? >> well, its 1 thread per block, but grc just generates the flow graph code, its technically out of the loop. >>> Why do you think you cant change the wire format? It sounds like you >>> changed it to sc8 format (above). >> Should have worded that more carefully. I can choose 8 or 16 bits over the >> wire. My thinking was that I might be able to increase the rate of >> decimation (on second thought, decimation has more to do with sampling >> frequency than a data bottleneck) and also decrease the precision and use >> an integer less than 8bits. Basically, I thought ethernet may have been >> the bottleneck. Decreasing precision shouldn't be necessary, I'm just >> trying to build an understanding here. >> ok cool >>> I prototyping whatever it is you are trying to do at a lower rate, then >>> optimizing it in SIMD routines to get up to 50 Msps on the host. >> I was totally unaware of SIMD before you mentioned it. That's an >> interesting subject. It is my understand that SIMD is integrated into >> gnuradio through VOLK as of Dec. 2010. Doesn't look like I can use VOLK >> directely from grc, or even from Python. Looks like it needs to be >> implemented at the block level in C++. Is this the case? >> >>> Also, try examples/tx_waveforms with --otw=sc8 --rate=50e6 and >>> experiment with that so you can see if your PC can sustain the rate with >>> minimal load. >> >> I actually couldn't find that in my /usr/local/share/gnuradio/examples >> folder. Do I need to download it elsewhere? >> <installprefix>/share/uhd/examples/tx_waveforms or in your build directory of uhd <builddir>/examples/tx_waveforms > Thanks for the informative post Josh! 50MSPS will probably prove unnecessary > for the project that I'm working on. I was worried that perhaps I was doing > something fundamentally wrong and that's why I wasn't getting the full > sampling rate out of this device. Thanks! -Josh _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
