[USRP-users] UHD time stamps on USRP1 vs N200

Thomas Tsou tom at tsou.cc
Thu Apr 18 01:06:17 EDT 2013


On Thu, Apr 18, 2013 at 12:02 AM, Sivan Toledo <stoledo at tau.ac.il> wrote:
> On the N200 the time stamps are very accurate (to within 1ns of what we
> expect, given the previous packet's time stamp and the sampling rate).
>
> On a USRP1 we do get time stamps, but they seem to vary in a range of about
> 200us. Are these time stamps derived from the time UHD got the packet on the
> host, rather than the time the samples were taken on the USRP?

Yes. The USRP1 has no UHD timestamp functionality in the FPGA and
relies on the host system clock. The values will not be nearly as
precise.

http://files.ettus.com/uhd_docs/manual/html/usrp1.html#list-of-emulated-features

  Thomas




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