On Dec 30, 9:28 am, Unruh <[email protected]> wrote: > [email protected] (Kevin Oberman) writes: > >> From: dhavey <[email protected]> > >> Date: Mon, 29 Dec 2008 12:07:25 -0800 (PST) > >> Sender: [email protected] > > >> Garmin specs say: The rising edge of the signal is aligned to the > >> start of each GPS second. This means edge on assert right? So flag2 > >> should be 0? > > >> What is going on here? > >On my clock (EndRun, not Garmin) the PPS is low true, so the rising edge > >is NOT the assert, but the rising edge at the end of the pulse. There is > >a difference between leading and rising. (I had to talk to an engineer at > >EndRun to confirm this was the case and it may not be for the Garmin.) > > Garmin defines the leading edge as the transition from 0V to 5V on the PPS > line. Now serial has two levels -12V and +12V. with capacitive coupling, > the garmin signal would be something like -2.5V to 2.5 V which really is > way out of spec for the serial port. (Or with the typicallysmall duty > cycle, more like -1V to 4V) > > >For EndRun, flag2 is 1. > >-- > >R. Kevin Oberman, Network Engineer > >Energy Sciences Network (ESnet) > >Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) > >E-mail: [email protected] Phone: +1 510 486-8634 > >Key fingerprint:059B 2DDF 031C 9BA3 14A4 EADA 927D EBB3 987B 3751
I don't see much difference in offsets between the two machines either way. Something else must be wrong. _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
