Hello, The same commands are available in the GNU Radio environment and I believe are exposed in the pre-release Python API branch.
The FPGA radio blocks contain a timekeeper which is a counter which increments at the same rate as the master_clock_rate which is the effective ADC/DAC sample rate. This allows for commands to be executed with very fine temporal precision. Regards, Derek On Thu, Mar 8, 2018 at 10:12 PM, Zhongyuan Zhao <zhz...@cse.unl.edu> wrote: > Hi Derek, > > I have two questions about the rx timed samples example, > 1. is there python version for timed command? > 2. Is the time stamp from the clock on USRP or on the host? > > Thanks > > Zhongyuan Zhao > > PhD Candidate, > Department of Computer Science & Engineering, > University of Nebraska-Lincoln > Office Hour: WF 9:30-10:00am, Avery Hall 12, > Suite 117, Schorr Center, > Lincoln, Nebraska 68588-0115 > > > On Thu, Mar 8, 2018 at 3:27 PM, Derek Kozel via USRP-users < > usrp-users@lists.ettus.com> wrote: > >> The stream command object has a field for a time spec of when to start >> streaming and a boolean flag for whether to make use of that time spec. >> http://files.ettus.com/manual/structuhd_1_1stream__cmd__t.html >> >> Here we can see it used in an rx example. >> https://github.com/EttusResearch/uhd/blob/maint/host/ >> examples/rx_timed_samples.cpp#L92-L93 >> >> Usually it is most practical to make a call to get_time_now() and then >> add an offset from that time which is returned. The minimum offset would be >> the roundtrip command time, usually a few milliseconds. >> >> Regards, >> Derek >> >> On Thu, Mar 8, 2018 at 9:03 PM, Andrew Thommesen < >> andrewjoh...@outlook.com> wrote: >> >>> No, how do you do that? >>> >>> >>> Sent from Outlook <http://aka.ms/weboutlook> >>> ------------------------------ >>> *From:* Derek Kozel <derek.ko...@ettus.com> >>> *Sent:* 08 March 2018 20:58:38 >>> *To:* Andrew Thommesen >>> *Cc:* usrp-users >>> *Subject:* Re: [USRP-users] TwinRx Channel Alignment >>> >>> Hello Andrew, >>> >>> Are you starting the streaming with timed commands? >>> >>> Regards, >>> Derek >>> >>> On Mar 8, 2018 7:32 PM, "Andrew Thommesen via USRP-users" < >>> usrp-users@lists.ettus.com> wrote: >>> >>> Hi all, >>> >>> >>> I have an x310 with a twinRx and would like to process coherent, >>> time aligned data within the FPGA. However, the data is not currently time >>> aligned and there is an offset of ~400 samples between the two channels. >>> >>> >>> The RFNoC radio block is configured to receive data on both channels, >>> with the LO of channel 1 set to companion. The output of the radio block >>> then passes through the RFNoC DDC block that decimates from 100MSPS to >>> 50MSPS. The decimated data then passes to a custom RFNoC block that strips >>> out the timestamps (for loopback). It is within this custom block that the >>> the offset is detected at the output of the AXI wrapper before any >>> processing has taken place. >>> >>> >>> Any ideas? >>> >>> >>> Andy >>> >>> >>> >>> >>> Sent from Outlook <http://aka.ms/weboutlook> >>> >>> _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >>> >>> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >
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