Hello, I have read through the docs on the wiki for estimating time2 with a nmea referecne clock. I have a Sure GPS after a week or so the offset seemed to stabilize round -450. Everything was making sense and then I came to:
"And now the truth about the PPS locking: actually only the sub-second part of the difference between PPS time stamp and (receive time stamp - fudge time2) is evaluated and checked. If this difference is less than 400ms or bigger than 600ms (which is equivalent to -400ms) the receive time stamp will be substituted with the properly adjusted PPS time stamp. This might sound a bit complicated, but if you have a device that sends the data before the associated PPS pulse, you can use the proper negative value for fudge time2 and compensate for that behaviour." I am a little confused about the absolute value of the offset but I think setting time2 to 0.450 is the correct approach. Am I right? Does the following chart accurately summarize when to use the a positive or negative time2? Offset w/PPS disabled | Value to use for time2 (offset/1000) ================================================================ -999 through -600 | Use negative offset -599 through -400 | Use absolute value for offset -399 through 399 | Use negative offset 400 through 600 | Use absolute value for offset 600 through 999 | Use negative offset I was not able to find a lot of information about how to identify what to use for an estimation of time1. The majority of what I have read seems to indicate that unless something is screwy ntpd will do okay with no value supplied for time1. Even if ntpd will do the right thing I was curious if there is any benefit at all to identifying a value for time1? How do I go about figuring this out? Part of me thinks that the answer may be using one of the utilities in pps-tools. Thanks in advance. _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
