Responses to several comments. Opportunities to collect critical NTP debugging data on the ISS will be limited. Specific suggestions sent to me off-list would be appreciated.
Earth station to ISS delays: I inferred the 600-700 msec RTT using the reported root distance [I've seen much higher delays on some terrestrial NTP paths. ] To really understand RTT / RTT stability NTP server diagnostic data is needed. GPS/GNSS, PPS distribution: seems like a good idea, but this is outside the area I'm helping with NTP (4.2.8) algorithmic changes are probably out of scope for the near future. If a real-world PLL problem can be documented, the ntp daemon maintainers might be motivated to investigate. So far I haven't been able to reproduce on my home Rpi some key features of the offset graph I showed. - pll error begins at -500 ppm - pll error grows to -1000 or even -1500 ppm - After step pll error is again -500 ppm - Does not self correct within 24 hours By placing large positive or negative values into the NTP drift file I can produce offset charts with a series of steps, but eventually the steps stop and the offset is small. Thanks for all the replies. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
