You will also have latency introduced by the ADCs themselves, as well as baseband analog filters if applicable. If you need very accurate calibration of arrival time, it is best to generate an accurately timed calibration signal using a GPS reference. You could continue to use your TX/RX loopback test, adding an oscilloscope to measure the time between the PPS rising edge and the RF output to determine TX latency.
On Sun, Feb 2, 2020, 1:41 AM YENDstudio . via USRP-users < usrp-users@lists.ettus.com> wrote: > Hi, > > I want to know the actual timestamp of TX and RX signals at the RF > antenna. For this I have add/subtract the group delay introduced by digital > filters in the TX and the RX paths from the UHD timestamp. Through loopback > test, I am able to calculate the aggregate delay, but cannot know the TX > delay and the RX delay separately. The UHD driver has APIs to get the list > of filters used in the signal paths. But my calculated values do not match > with the loopback delay I measured. Could someone help me with this? I am > using USRPB200 set with 30.72 MHz master clock rate and 1.92 MHz sampling > rate. > > Regards! > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
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