Hello Mike, Here is a simple, but clever, flowgraph put together by Nate Temple which does exactly what you describe. It isn't an answer to the time errors you've seen, but I hope it is useful anyways.
Regards, Derek On Tue, Aug 16, 2016 at 9:08 AM, Marcus Müller <[email protected]> wrote: > Hi Michael, > > what USRP are you using, and which version of UHD? > > > Best regards, > > Marcus > > On 16.08.2016 17:41, Michael Giallorenzo wrote: > > Hi everyone, > > I'm currently trying to develop a gui for recording selected samples of > data while viewing the spectrum (the user can watch a waterfall display of > the readings being taken on an Ettus x310, and press and hold a button to > record data when the spectrum looks interesting). > > The combination of the burst tagger block and the tagged file sink block > in GRC seem to be the perfect solution to this, but I'm noticing an error > whenever i change the frequency during execution. The timestamps recorded > in the resulting filenames rapidly jump ahead in time (easily confirmed by > comparing the filenames to the output of the tag debug block or writing the > same data to a metadata file and reading its header). When I'm using my > GPSDO as a time source, the time starts out in sync with GPS but rapidly > gets corrupted as i change the frequency. Likewise when I use relative > time, timestamps start at 0 but increase too quickly. > > As far as I can tell, this is because the tagged file sink block is not > seeing the rx_time tags on the data stream and is instead trying to > calculate the time based on the sample rate, but is confused when the > changing frequency results in extra tags that are effectively being > generated faster than expected. > > I'm fairly new to gnuradio and my background isn't really software but > I've been experimenting with OOT modules and have modified a few built in > blocks to suit my needs before. In "tagged_file_sink_impl.cc" around line > 100, i believe time_tags_outer.size() is returning a value of 0 and that > may be the source of my problems. Perhaps this stems from my lack of > understanding of how the scheduler calls the work function (ie how is the > value of noutput_items determined?), but I'm not really sure how to modify > this or really why this is happening. > > Sorry if my thoughts here are kind of all over the place. Any insight or > reading material that anyone could offer would be greatly appreciated. > > Thanks, > > Mike G > > > _______________________________________________ > Discuss-gnuradio mailing > [email protected]https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
grc_recording.grc
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