Hi Harry - Actually, the name `tick_rate
On Tue, Nov 26, 2013 at 5:49 AM, Harry Zhang <zhang...@gmail.com> wrote: > Dear Marcus, > Thank you for your reply. > I'm confused about two concepts. Referring to the file time_spec.hpp > in UHD, fractional sec is calculated according to the parameter ticks and > tick_rate. So I think the time granularity is '1/tick_rate' which is > 0.1us using 10Mhz clock. But for the timestamp of sample stream, the > granularity is the sample duration. Is it correct? > > Best, > Harry > > 2013/11/26 20:12, Marcus Müller wrote: > >> Hi Harry, >> >> as far as I know, the granularity of a time stamp is the sample duration >> at the downsampled side. >> As for the 10MHz: The 10MHz clock is used to derive different other >> clocks, especially the rx ADC and tx DAC clocks, which are an order of >> magnitude higher; bear in mind that when you request e.g. "5MHz samle rate" >> you still get the 100MHz* samples of the ADC, but downsampled by a factor >> of 20. >> >> Please also bear in mind that due to physics, processing etc the >> timestamp of the rx side is delayed to the actual reception of "that >> sample", and that this delay is largely constant when receiving using the >> same settings, but my change based on sampling rate and other factors. >> >> Greetings >> Marcus >> >> *for USRP2 arch, if I remember correctly. >> On 26.11.2013 13:04, Harry Zhang wrote: >> >>> Hi, >>> Since we can get receive time of rx_stream's first sample via rx tags, I >>> have two questions about the time granularity. Given the internal clock >>> is 10Mhz, is the time granularity 0.1us? The fractional second is stored >>> double type. Does it mean the last digits of the fractional sec are >>> invalid? >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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