That is great info. I appreciate it Richard. Thanks!
-- David -----Original Message----- From: Richard Cochran <richardcoch...@gmail.com> Sent: Wednesday, February 24, 2021 10:08 AM To: Coughlin, David S (US) <david.s.cough...@lmco.com> Cc: Linuxptp-devel@lists.sourceforge.net Subject: EXTERNAL: Re: [Linuxptp-devel] lstab_utc2tai On Wed, Feb 24, 2021 at 02:42:12PM +0000, Coughlin, David S wrote: > We sourced a grandmaster clock board from a vendor that advertised GPS > integration. We are using an ICD-GPS-153 compliant receiver, and I had > to rewicker ts2phc to interact with it. Most of my changes were built > off of ts2phc_nmea_master.c . We were reconciling our times with > external clocks. Our external clocks were behind what we were getting > out of ts2phc by 40+ seconds. I looked through the code and saw that > it was calling lstab_utc2tai() . I pulled the thread on that, and saw > that a good chunk of our delta is due to adding back leap seconds. As the name of the function suggests, the purpose of this call is to convert UTC time values into TAI. > My systems engineer thinks we should just straight convert the UTC > time tag to PTP time. Correct, and that is what the function call does. > Can you shed some light on the decision to add the leap seconds in > when using a GPS upstream master? The reason is that, according to the IEEE 1588 standard, the PTP time scale is TAI. HTH, Richard _______________________________________________ Linuxptp-devel mailing list Linuxptp-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
