[ntp:questions] IEEE 1588 (PTP) at the nanosecond level?

Martin Burnicki martin.burnicki at meinberg.de
Tue Mar 18 09:26:31 UTC 2014

Joe Gwinn wrote:
> I've used IRIG-B004 DCLS before, for cables two meters long within a
> cabinet.  Worked well.  How well do they handle 100 meter cables, in
> areas where the concept of "ground" can be elusive?

You could use fiber optics to transfer an IRIG DCLS signal.

However, if you want highest accuracy you need to take care how much 
delay is inserted by the transceivers, and the length of the connection.

PTP has the advantage that constant delays can be measured and 
compensated automatically.

In any case it's a good thing if you can measure the accuracy, e.g. 
compare a 1 PPS slope generated by a time client to a 1 PPS slope 
generated by the device providing the time.

This helps to find out if the time transfer suffers from uncompensated 
delays (IRIG) or asymmetries (PTP).

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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