Keep your pc clock synchronized

October 2nd, 2010, 05:50 PM

Is it me or IB, I always more than 1 second ahead. I tried both programs, same result. I used win7 64bits and dont know if this might be the problem

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July 12th, 2011, 05:26 AM

Thank you guys for this information. I was once very upset to use the button "reload historical data " ( control+shift+r) in NT.

December 21st, 2011, 07:20 AM

I had a hard time using NTP, and tried to find out what the issues were.

It appears that NTP works needs symetrical delays on the network. If the up/down delays become assymetrical, this ends up with an error :

example of NTP queries against a stratum 1 server :
no network traffic :
Reference ID: TS-2
Root Delay: 0 ms
Root Dispersion: 1,7242431640625 ms
Round Trip Delay: 35,1391 ms
Local Clock Offset: 2,92545 ms

heavy download:
Reference ID: TS-2
Root Delay: 0 ms
Root Dispersion: 1,89208984375 ms
Round Trip Delay: 108,8157 ms
Local Clock Offset: -32,88685 ms

heavy upload :
Reference ID: TS-2
Root Delay: 0 ms
Root Dispersion: 2,1209716796875 ms
Round Trip Delay: 66,39 ms
Local Clock Offset: 18,5578 ms

So depending on your network traffic during the queries, your local offset estimation can vary a lot , and NTPV4's feedback loop will go crazy.

So the idea is "let's get rid of the network"

I used the tutorial here : NTP on Vista and Windows-7

You need a 35 USD GPS board that provides a 20 ns PPS precision (see measurements : MG1613S GPS Receiver)

Then all you need to do is solder a wire on the board as per the tutorial,

and voil� :

10 �s jitter clock, for 35 USD, I'd say this is awesome. But I'm a geek, so I find lots of stuff awesome that other people don't ;-)

January 10th, 2012, 10:28 AM

gomi

I had a hard time using NTP, and tried to find out what the issues were.

10 �s jitter clock, for 35 USD, I'd say this is awesome. But I'm a geek, so I find lots of stuff awesome that other people don't ;-)

LOL

Ducman

January 11th, 2012, 05:16 PM

gomi

I did some research on this time sync issue.

Basically, the way "NTV V3" clients, like the Windows Time Service, work, is by regularly querying the time on a Time Server, updating the computer time, and waiting for next resync.

This is not a very good solution because
1. each time measure is not very precise
2. anyway the clock drifts between two measurements.

The solution is to install an NTP V4 Daemon. This system corrects both flaws : it uses multiple time sources to increase the precision of the time measurement, and it continually adjusts the local time clock using a PLL. It evaluates the hardware clock drift and keeps correcting it.

@ gomi,

Installed the latest version, went smooth. My PC was also off a few seconds.

@cunparis

Thanks for bringing the subject up!

Ducman

January 11th, 2012, 05:48 PM

If you installed NTP V4 daemon, you might want to check what you offset looks likeover time
You can use Meinber NTP monitor
NTP Time Server Monitor

here's mine for today : still about 10�s accuracy

January 12th, 2012, 05:59 PM

gomi

If you installed NTP V4 daemon, you might want to check what you offset looks likeover time
You can use Meinber NTP monitor
NTP Time Server Monitor

here's mine for today : still about 10�s accuracy
Attachment 59407

I get errors when activating the statistics, can't stop or start the NTP service from out the monitor. Tried various new installs but no luck so far.

Ducman

January 12th, 2012, 06:25 PM

If you want to start/stop the service, you need to run the monitor as administrator.

Just in case, here is my conf file :

# ref-clock drivers
server 127.127.22.1 minpoll 4 # PPS - serialpps.sys
server 127.127.20.1 minpoll 4 mode 18 prefer # NMEA serial port, 16 = 9600 baud, 2 = $GPGGA

# Other servers
server 0.fr.pool.ntp.org minpoll 10
server 1.fr.pool.ntp.org minpoll 10
server 2.fr.pool.ntp.org minpoll 10
server 3.fr.pool.ntp.org minpoll 10
###########################################################
#Section insert by NTP Time Server Monitor 20/12/2011

enable stats
statsdir "C:\NTP\etc\"
statistics loopstats
###########################################################

driftfile c:\ntp\etc\drift

January 13th, 2012, 06:32 PM

I use AtomTime Pro..it is a free download..works on XP & Win7 and can be done manually or on auto...

Free is Good..

Regards,

Tom

Keep your pc clock synchronized

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Keep your pc clock synchronized