mlewis000@rogers.com said: > - GPS module's secondary PPS disciplining the RTC-counter-divider PPS by > resetting the RTC's counter/divider (I'm assuming there's one that will > rest fast enough to sync; I've never looked into these...) How many RTCs accept an external PPS? Your plan sounds complicated. If the external PPS comes in roughly the middle of the RTC second, how does the RTC decide whether to go forward or backwards? Does your GPS disable its PPS when it isn't locked? If not, you need additional logic to mask it so the RTC doesn't track a drifting GPS. I'd let the RTC free run, feed its PPS to a "clock" program, and then feed the offset to ntpd via SHM. -- These are my opinions. I hate spam.

On Thu, November 2, 2017 5:19 am, Hal Murray wrote: > I'd let the RTC free run, feed its PPS to a "clock" program, and then feed > the offset to ntpd via SHM. I would just get a GPS that doesn't shut off the PPS when it loses lock and that has a decent TCXO for the clock. Or just use a rubidium and call it close enough. -- Chris Caudle