On Thu, Jun 23, 2011 at 7:21 PM, Colby Boyer <colby.bo...@gmail.com> wrote:
> > > On Thu, Jun 23, 2011 at 4:11 PM, Nick Foster <n...@ettus.com> wrote: > >> >> > >> > >> > >> > >> > Where should I look for the API to tag samples on the USRP? >> >> Tagging in this case has nothing to do with the USRP and everything to >> do with Gnuradio. Take a look at the burst_tagger in >> gnuradio-core/src/lib/general/gr_burst_tagger.cc for an example. >> >> The Mode S decoder I wrote also uses tags throughout for preamble >> tagging and framing, and can be found at >> git://github.com/bistromath/gr-air-modes.git. >> >> --n >> >> > >> > >> > --Colby >> >> >> > I think it does have something to do with the USRP. I need to know at what > time my TX sampled got processed by the USRP, as this is the trigger for an > RX burst. > > --Colby > At one point, we looked into outfitting the UHD source block to read the packet metadata from the USRPs and send a tag when we saw a new time stamp. We took it out for efficiency reasons, but I think you could make another class like gr-uhd/lib/gr_uhd_source_tagged or something like that. Look at the metadata in the UHD packets, see if the timestamp is valid (there's a flag for that), and then you can extract the time and make it a new tag. Tom
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