[time-nuts] Possibly off topic - Jitter on Ethernet over poweradapters

David J Taylor david-taylor at blueyonder.co.uk
Sun Feb 10 06:38:45 EST 2013

From: Rob Kimberley
I'm not sure if this is the best place to ask the question, but does anyone
have experience of using Ethernet over power line adapters? I have an
outside office, and my router is in the house plugged into the phone master
socket. I have used two Ethernet over power adapters, one at the router and
one in the office here to get internet access. The output of the adapter
then goes to a multi-port hub to give me Ethernet to all my office devices
including two Meinberg NTP servers.

I've noticed large jitter readings on Meinberg's NTP monitor program.  Can
be as low as 2ms, but much higher (50mS +), and at this point NTP goes

Not sure if it is the physical set up or something else.

Any comments appreciated.




It's not quite clear which direction you are measuring.  I take it your 
Meinberg servers are "perfect" in NTP terms, and you are monitoring from the 
house?  Or vice-versa?  Anyway, my first guess is that jitter might be not 
dissimilar to Wi-Fi, in which case my lightly-loaded Wi-Fi results might be 
a starting point:


Note the improvement with Windows-8 and the latest NTP (top graph, PC 
Bergen), and the others are somewhat variable.

SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk 

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