(my first post on eevblog. Dave if you read this, I cant count the number of times your videos made my day, thanks for each and every one of them, keep going.)
I even think, that GPS is an accepted way to have traceable time uncertainty.
GPS is at the time not considered traceable. The reason for this boils down to GPS Time (gps system time) as a
timescale NOT being UTC(USNO). GPSTime is steered to UTC(USNO) but that steering process (or any other
intermediate that leads from GPS Time to UTC(USNO)) is a black box to the BIPM's eyes, and a black box in a
traceability chain means no traceability (check
https://www.bipm.org/en/cipm-mra/ for some details)
So standalone measurements made between a local reference (your Cs clock) and GPS Time (as realized by
your GPS receiver) are not considered traceable ; traceability requires that you get rid of GPSTime in your traceability
chain. You do so by subtracting your standalone measurements vs GPSTime to those made simultaneously at the
primary lab you want to establish traceability to (NIST in the US, NPL, in the UK, NMI in Australia,
LNE in France... all operate similar services). That is how frequencies (more than time itself) are primarily disseminated
in a traceable way. So my feeling is that in the traceability table at 9:40, there is a missing link between the Cs frequency
standard and the NMI : the traceability of the Cs to TAI probably goes through NMI ; no way that Keysight directly deals
with the BIPM at that point.
Still, I am also eager to see the Cesium tank attached to a 5071A running continuously for 23 years
)
--
fm