[LinuxPPS] PPS with non-atomic reference through network

[Maximilian Brehm]

Hey LinuxPPS community,

in a local network I have I would like to have a system with temperature independent oscillators with a known drift (up to ±2ppm) and a destination system with standard computer oscillators (up to ±100ppm). I would like to use the the timestamps of the first system as a reference for the second to adjust the systems clock (CLOCK_REALTIME). The reference system can not run a NTP server but it sends timestamps. The timestamps are transmitted to the second system at relatively high frequency and used for other purposes. They do not reference the absolute time but the relative time since the start of their origin system.

What I would like to do is to use the shared memory driver of NTP in combination with PPS. A few problems are: (1) the non-atomic reference clock, (2) the relative time in the timestamps, (3) the timestamps are not provided through a device, (4) the network and processing delay.

(4) should be solved by PPS and PLL/FLL. For (2), an offset could be determined in the second system when receiving the first timestamps. For (1), this offset has to be regulated when the clock drifts off. Do you think this is correct? Now, the reason I set up this message is (3). Do you think I can use the Kernel-PPS? Or should I am implement the PPS routine for the shared memory driver? Any general advice?

Regards
Maximilian Brehm