on board GPSDO?

[Sylvain Munaut]

Hi,

> I checked out the git found the GPS 1pps signal was terminated to
> FPGA, and wonder how the discipline algorithm was implemented. Someone
> would give me a hint or introductory?

Simple PID control. Look at the ZPU firmware (soft cpu core inside the FPGA).

We don't need a "time-nut" level of accuracy here so this simple
control works well. Could be improved to handle corner cases though.

Cheers,

   Sylvain