Thanks for the response Josh. Unfortunately I am still clueless on how to accomplish my task. So let me explain what I am trying to do.
There are two nodes (a node has a N210+WBX and a powerful enough CPU) and I want both of them to transmit a carrier signal at the same time. This is the sequence of steps I am thinking of: Step1: Node1 transmits a reference (trigger) sequence Step2: Node2 correlates on the reference and finds the time at peak correlation Step3: At a certain time T from the peak-time, both Node1 and Node2 transmit a carrier signal (const_wave) reasonably simultaneously -- Having described the task, let me take a stab at how I would go about it. 1. Note t1 = timestamp of last sample of reference sequence. t2 = timestamp of peak correlation sample. Set time reference according to t1, t2. 2. Assume there is a gr_signal_source that accepts time offsets from time reference and populates metadata accordingly. 3. Assume gr-uhd recognizes the metadata and transmits the buffer at the right time. I understand that metadata does not get through in gr-uhd (at least currently)... but I am not sure how else the task can be done. Any comments/suggestions will be greatly appreciated. Thanks, Ragh >> Hi All, >> >> I have used gnuradio-companion and the N210 without too much problems. >> What I would like to do, however, is to send data at particular time >> instant, something like tx_timed_samples.cpp. But I would prefer to do >> this in python for various reasons. I am new enough to this stuff that >> I can't tell if this can be done with the current code (gnuradio + >> uhd) or if this requires some effort to do and if so, what is the best >> path to follow? >> > > The thing about gnuradio is that something has to be written in C++ at > some level. So, we have this tagging interface in gnuradio which can be > used to decorate samples (example: timestamps, end of burst, ...). > Currently, the gnuradio-uhd blocks dont do anything with the tags, which > could easily change, but... tags are pretty new and we havent yet > invented the block that would take some kind of input and generate a > tagged/decorated output stream that the uhd sink block would use. So > maybe you can invent that motivating example. I should note that this > may be a better discussion for the gnuradio mailing list. > > -Josh > > _______________________________________________ > USRP-users mailing list > [email protected] > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
