[time-nuts] Possibly off topic - Jitter on Ethernet overpower adapters
robkimberley at btinternet.com
Mon Feb 11 11:38:22 EST 2013
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of David J Taylor
Sent: 11 February 2013 16:13
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Possibly off topic - Jitter on Ethernet overpower
Strangely today the jitter numbers seem to be behaving themselves! Nothing
has been done to the set up.
Thanks to everyone for their comments. I'm looking at putting a direct
Ethernet cable in here to see what the difference might make.
Attached is a picture of latest NTP Monitor readout. Bottom two devices are
the Meinberg LanTimes. The others are pool servers.
Two comments from your screen-shot.
- NTP version 4.2.4p8 is now rather old. You may well find better
performance using a more recent version, and especially with the most recent
development versions on Windows-7 and Windows-Vista. There are some upgrade
notes on my Web site.
- with a local stratum-1 server, you can get better performance using a more
frequent poll i.e. limit maxpoll. For my PCs I typically have (with NTP
4.2.6 or later):
# Local stratum-1 LAN-based servers
server 192.168.0.3 iburst minpoll 5 maxpoll 5 prefer # Pixie
server 192.168.0.2 iburst minpoll 5 maxpoll 5 # Feenix
# External servers from the UK pool
pool uk.pool.ntp.org minpoll 10
For measurement, you may want to let the poll interval drift to 1024s, but
for lower offsets keeping poll to 32s (maxpoll 5) gives better results.
My apologies if you were already aware of this.
Many thanks for that. I do have a copy of 6.2.6 which I have tried, but the
jitter numbers appeared higher. I will try again and also change the minpoll
settings as suggested.
The settings shown were the default settings from Meinberg and I haven't
Will see what I get.
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