The best way to achieve this was to check the time against a source that was using an atomic clock. The classic way to do this was to access a site such as:
http://time.gov/HTML5/
I just noticed a handy new site which shows the current time and how far out your computer's time is:
http://time.is/
This site reported that my own computer was within a second of the right time. That's because it is configured to set its time periodically from the following site:
time.nist.gov
This automatic setting of time is based on the "Network Time Protocol" (NTP). Many corporate networks are configured these days to "push" the correct time to servers and workstations.
For many years now I have been travelling to/from work by train. This has made me dependent on knowing the EXACT time while on the go.
A number of years ago I tacked this problem by buying myself a watch which always shows the correct time: a Casio Wave Ceptor watch.
These watches synchronise themselves once a day with a radio signal which sends the correct time based on an atomic clock. Here is Ireland the closest transmitter is the National Physical Laboratory in Teddington near London.
As well as having the correct time all of the time, my watch also adjusts to/from summer time automatically.
Nowadays people tend to look to their smartphones for the current time. And the phones can be configured to pick up "network time". But I tend to still look to my watch for the exact time. And I noticed during the week that my phone was not displaying the correct time even though network synchronisation is enabled.
The only criticisms I would have of my own Wave Ceptor are:
- Although the time is always right, the watch hands are not. You need to adjust them manually
- The particular model I chose has a small digital display which can show the date OR the hour and minutes OR the seconds. When I buy my next one I will want to see all three at once.
I would recommend a Wave Ceptor watch to anyone who is interested in knowing the EXACT time.
