I bought a cheap £20 USB GPS interface (VK-162, which I'm led to believe has PPS) and plugged it into a hAP ac. I added the GPS and NTP packages and within a few seconds, the MikroTik picked up the time and happily pushed it out to other devices over NTP identified as Stratum 4. That made me quite happy!
I've been monitoring it for about 24 hours now, and it's about 56 ms out, with maybe +/- 5 ms jitter. I appreciate that RouterOS v6 doesn't support PPS, so can't get down to microsecond accuracy, but would it be possible to put a user offset in? If I could insert a 56 ms offset, I'd have an NTP server with an accuracy of +/- 5 ms which is closer to what I would expect of Stratum 4 than the current 56 ms always late.
And is it likely that RouterOS v7 will support PPS? Do current cheap MikroTik models have the necessary hardware?
Many thanks for any input ...