Hi Marcus and Derek, Thank you for the reply. The RFNoC and synchronization are very helpful. I have an additional question regarding to the timestaming in GNURadio.
In the VITA and CHDR format of RFNoC, there are timestamp and stream ID, what could I do to keep the timestamp and stream ID via a file sink of GNU Radio? or make 2 streams aligned within GNU Radio? I know that there are metadata in file sink, but I am not sure if the metadata timestamp is from the RFNoC or the host (at the moment it write IQ data to file). Is there any application notes regarding to this? Thanks again! 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 Fri, Mar 9, 2018 at 1:15 PM, Marcus D. Leech via USRP-users < usrp-users@lists.ettus.com> wrote: > On 03/09/2018 03:23 AM, Derek Kozel via USRP-users wrote: > > Hello, > > Yes, that is the purpose of the set_time_next_pps function. When combined > with common 10 MHz and 1 PPS references this allows for stable time > synchronization of 1 sample clock cycle, 5 ns at 200 MS/s. I recommend > reading through the examples which show using all these commands and others > related to streaming multiple channels. > https://github.com/EttusResearch/uhd/tree/maint/host/examples > > The manual also covers these topics. > http://files.ettus.com/manual/page_sync.html > > Derek > > There's also, of course: > > https://kb.ettus.com/Synchronization_and_MIMO_Capability_with_USRP_Devices > > > > > On Thu, Mar 8, 2018 at 11:02 PM, Zhongyuan Zhao <zhz...@cse.unl.edu> > wrote: > >> Hi Derek, >> >> If USRPs A & B clocked by an Octoclock, are connected to the same host, I >> want calibrate the counter values from USRPs A and B. How can I do it? Is >> this function supported by UHD? If not, could I update the counter values >> in the FPGA Radio blocks? or I can only keep an calibration table of >> counter value offsets on my 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 4:42 PM, Derek Kozel <derek.ko...@ettus.com> >> wrote: >> >>> 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/example >>>>> s/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 >>>>> >>>>> >>>> >>> >> > > > _______________________________________________ > USRP-users mailing > listUSRP-users@lists.ettus.comhttp://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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