How long was the observation period between the initial and final estimation? Were the devices powered cycled, or GPSDO re-locked between each test?
On Thu, 7 Aug 2025 at 19:31, <nirkicat...@gmail.com> wrote: > Hi, > > We are observing a time difference of arrival (TDOA) variation between two > E320 devices using PCM signals. > > - > > The devices receive with zero hardware delay delta to the RF inputs. > - > > Both devices have the latest filesystem installed (UHD 4.8). > - > > Matched filtering is applied to estimate the time of arrival of the > pulses. > - > > The time of arrivals are subtracted to compute the TDOA. > - > > Internal GPSDO PPS and 10 MHz clocks are used. > - > > cgps reports GDOP values around 2.0 for both devices. > - > > Multiple 60-second test runs have been conducted. > - > > A deviation of around 150 ns in TDOA between the initial and final > estimations across the radios is observed. > > We know that the matched filtering estimation and other imperfections > follow a stationary Gaussian distribution with a 20 ns sigma (and a > constant mean per run). We verified this behavior on the same setup using > two B210 devices with external Ettus-supplied GPSDOs. The B210s report > similar GPS performance to the E320s. > > What could be the cause of the non-stationary behavior observed on the > E320s? > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com >
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