logoalt Hacker News

sgillenyesterday at 7:31 PM2 repliesview on HN

We don't use NTP, but for robotics, stereo camera synchronization we often want the two frames to be within ~10us of eachother. For sensor fusion we then also need a lidar on PTP time to be translated to the same clock domain as cameras, for which we also need <~10us.

We actually disable NTP entirely (run it once per day or at boot) to avoid clocks jumping while recording data.


Replies

wpollockyesterday at 8:04 PM

> We actually disable NTP entirely (run it once per day or at boot) to avoid clocks jumping while recording data.

This doesn't seem right to me. NTP with default settings should be monotonic. So no jumps. If you disable it Linux enters 11-minute mode, IIRC, and that may not be monotonic.

show 2 replies
opelloyesterday at 9:38 PM

In your stereo camera example, are these like USB webcams or something like MIPI CSI attached devices?

show 1 reply