On Fri, May 25, 2012 at 12:29 AM, Terje Mathisen <"terje.mathisen at tmsw.no"@ntp.org> wrote:
> Chris Albertson wrote: > >> Next how to get the PPS to be at the top of the second. Two methods >> >> 1) don't bother. Linux PPS will log the time of both the GPS's PPS >> and the Rb PPS. Read the log file to determine the offset. This give >> offset with uSec precision. To get better you need a hardware time >> interval counter. I happen to have a few of those and can read >> sub-nanoseconds but this is gross overkill. Microseconds are good >> enough for NTP...... >> > > Much simpler would be to use a fudge command to specify the current phase > offset between the Rb and GPS PPS signals, i.e. if the Db happened to start > out 367 ms off, just let ntpd know that these pulses are supposed to have > such an offset. > > Yes, correct the "fudge" method is what I was getting at in #1 above. I assumed that every on here would know to use the measured difference in a "fudge" but the key is measuring the offset. Get that from the log file. or a TIC if you have one. But there is a problem in the even with the best Rb the offset will drift over time. Chris Albertson Redondo Beach, California _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
