Kernel
Posts: 395
Joined: Sat Mar 03, 2012 12:53 pm

Re: How accurate is your clock?

Fri Mar 16, 2012 8:38 pm

http://time.is/




Your clock is 2.3 seconds fast.


Accuracy of synchronisation was ±0.032 seconds.


Then sync'ed it with time.windows.com and:




Your time is exact!




The difference from Time.is was +0.042 seconds (±0.085 seconds).



error404
Posts: 351
Joined: Wed Dec 21, 2011 11:49 pm

Re: How accurate is your clock?

Fri Mar 16, 2012 9:04 pm

Very neat (and easy to remember) website. I will definitely be using this, thanks.

As far as accuracy, for a while I ran a GPS-based stratum-1 time server, but I took that apart to use the components for some other experiments and never put it back together... Now I just run a regular old NTP server on my LAN, which gets its time from official time servers at NRC in Canada and NIST in the US. That system currently thinks its about 0.5ms off, and a desktop machine on the network says:




Your time is exact!


The difference from Time.is was -0.003 seconds (±0.025 seconds).



My Windows machines sync to the same server, but the SNTP client in Windows is pathetic and can barely get within a second even just after syncing. You need to run a proper NTP implementation to get decent time on a Windows machine.

Andre_P
Posts: 241
Joined: Sun Aug 28, 2011 7:57 am

Re: How accurate is your clock?

Fri Mar 16, 2012 10:54 pm

Sometime ago I worked for a company that looked at SONET and specifically clock recovery stuff.

One of the things I did was to measure the Wander and the Jitter of the resulting recovered clock.

Using a good quality temperature controlled crystal some of the measurements were down in the femtosecond range.

One of the things that gave me an idea of time is the idea of a Shake. It takes 3 Shakes for the entire radiological process to complete of a Fission Weapon, and a Shake is 10 ns.

So should you decide to detonate a weapon the RPi would have executed about 21 instructions (assuming single cycle, no stalls and Cached).

Don't try this at home

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