Alan Cox wrote:
The master node in a PTP network probably takes its time from a
precise external time source, like GPS. The GPS provides a 1 PPS
directly to the PTP clock hardware, which latches the PTP hardware
clock time on the PPS edge. This provides one sample as input to a
clock servo (in the PTPd) that, in turn, regulates the PTP clock
hardware.
A PTP clock is TAI, Unix time is UTC.
Not necessarily. AFAIK, the time distributed by IEEE1588v2 can either be
based on the "PTP epoch" (timePropertiesDS.ptpTimescale=TRUE) and thus
represent TAI or be based on an implementation specific arbitrary epoch
(timePropertiesDS.ptpTimescale=FALSE) and represent time on some
arbitrary time scale.
Christian
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