How To Sync Your Computer Clock

Methods to Synchronize Your PC Clock

How to Sync Your PC Clock

In classic amateur radio operations, the need of a good time synchronization has always been a requirement, for contact logging purposes, or for example in APRS and packet radio systems.

Nowadays, in the weak-signals digital modes era, with time synchronized protocols like FT8 FT4 JT65 and JT9, an accurate time synchronization of your PC clock with an atomic time service has become mandatory.

Time sync has become a so important factor, that makes the difference between being able to make contacts and not to be able.

Synchronizing your computer time it may be very easy task, and sometimes a challenge.

How to know if your computer is perfectly syncronized.

A very simple way to know if your PC Clock is synchronized, is to visit the web site and check the difference with your PC clock.

According to current UTC time is:

The ham radio way

In case you have no internet access, and want to know if your PC is in time sync, try starting from your PC a weak signal software, for instance, WSJT-X or JTDX session and tune into a FT8 Frequency. If you will be able to decode signals, it will mean that you are almost in time sync, and therefore, you don’t really need an additional synchronization.

If you pay attention to the graph, and you see green lines overlapping descending most of the signals, it will mean that your clock is not in sync, and no signals will be therefore decoded.

FT8 signals with a wrong time sync

Fast modes like FT4 where data is exchanges in 8 seconds, having an accurate time synchronization is even more important.

FT4 signals with an accurate time syncronization

How to sync computer time with internet

Time synchronization in modern operative systems is often built-in, but some times, difference of even half a second may be the cause of problems on decoding signals.

However, under modern Microsoft and Apple operative systems like Windows 10 or MacOSX 10.x you can use a simple commands from Command Prompt or Terminal. These commands will time sync your PC with internet NTP time servers.

NTP Servers

Time services are provided in Internet by Network Time Protocol Servers.
NTP servers are internet services whose job is to provide the current time. They are often very accurate ther are hundreds of them in the net. Said that, we suggest you to choose the closest to you.
You can find a list of NTP servers on these web sites.

Once you have selected one, you can then execute the sync command as in the examples below, just changing the address we use in the examples below.

Windows time sync command

net time \\ /set /y

Mac OSX time sync command

sudo sntp -sS

Linux time sync command

ntpdate -u

Computer Time Sync Software

In addition to sync commands, that will need to be manually executed, we selected for you some of the most popular programs used by hams, that you can easily install on your PC in order to accurately and continuously sync your computer clock with internet NTP servers.

How to sync your PC time without Internet

In the era before internet, time synchronization was already a need, and sync methods were mostly based on GPS data reception.
Even today, this technique can be very useful for amateur radio portable operations, especially for those who operate in remote locations, where mobile data connection is not available, but where GPS system still works.

For this method to work, you will need an external GPS receiver attached or integrated in your PC.

An interesting article by W0JD explains how to sync clock of your PC with a GPS receiver.

GPS Time Sync Software

Time Sync with FT8

If you are into amateur radio, another cool method to sync you pc time, is to download and use JTSync program. This nice piece of software will reverse the scope. It will not sync your PC time in order to receive FT8 signals, instead, it will use the received FT8 signals to determine the correct time and to accurately sync your clock. Genius!

In conclusion, nowadays to sync a computer clock with or without internet is not really a great problem. If you need you may find additional interesting Internet and GPS time synchronization programs in our links directory

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David Barbiere
Interested on shortwave listening and two-way communications since early 70s, spend my time listening to broadcasting stations looking for rare dx stations, as well as listening on amateur radio bands as SWLers.

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