FT8/JT65/JT9 Workstation GPS time sync

Update: 23.Feb.15
I have been getting alerts that the Dimension4 website link below has been down on occasion. Meinberg also has a Windows NTP client available at https://www.meinbergglobal.com/english/sw/ntp.htm

As FT8, JT65 and JT9 are a time synchronized protocol, one soon discovers that an accurate PC clock is very important. If your workstation time is off it can cause you to send when no one is listening, or to listen when no one is sending.

The simplest solution is to install an NTP client and be on your way. If however your internet connectivity is a bit dodgy or you want the ability to operate without (gasp !! ) internet connectivity. Then a local NTP server with a GPS reference may be just the ticket.

GPS Receiver

While the dedicated NTP sites frown upon the use of a GPS receiver which does not have a PPS output. My goal is usability and not perfection and this system is very usable.

GlobalSat BU-353-S4 USB GPS

GlobalSat BU-353-S4 USB GPS

Shopping List

Sits above my desk on a shelf and has no trouble getting a lock through the roof.


GPS Info screen shot

GPS Info

The next step was installing a NTP server on my Windows 7 workstation. I used the Windows binary installer available on the Meinberg website and while I was there I also downloaded the NTP Time Server Monitor.

After installing both packages the first step is to adjust the ntp.conf file to make use of your GPS receiver. The first step is finding what port it is on, an easy way to do this is to download GPSInfo from the GlobalSat website.

Next in the comm port drop down. Look for ports which have the Prolific driver and select it. Press the Start GPS button to test that the port you selected is the GPS. If not rinse and repeat until you find the correct port. Once you locate the port, make note of it and exit GPSInfo.

NTP Server Setup

With the GPS port found next step is to setup the NTP service to use it. A simple way to manage the NTP service and edit the ntp.conf file is via the NTP Time Server Monitor app. However as this app has not been updated for Windows 7 it needs to be run with admin privileges in order to write the ntp.conf file.  This is easily done via the shortcut properties.

Run NTP Monitor as an administrator

Run NTP Monitor as an administrator

Next setup up the location of of the config file. Typical if you installed with the defaults is “C:Program Files (x86)NTPetcntp.conf”.

NTP Monitor Setup screen

NTP Monitor Setup screen

ntp.conf setup

Once you can edit the conf file you can comment out everything except the restrict and driftfile line in the stock file. Next need to add in a line to bring in the correct reference clock driver, which for us is the NMEA GPS Receiver driver.

You can read all about it at http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html

The last octet is the serial port, so as in my case if your serial port is 11 the line will read:

server minpoll 4 prefer

If your port is different then adjust the port accordingly and save the file.

2014-10-22 22_04_46-Meinberg NTP Software Downloads

 Starting the service

Back on the main tab, start or restart the service for the updated config to be read.

GPS Monitor main screen

GPS Monitor main screen

Flip over to the Status tab and give it sometime for the jitter to settle down.

NTP Monitor console

NTP Monitor

 In closing

So far my GPS time sync setup has been stable and is keeping me in sync 😉

WSJT-X Waterfall

WSJT-X Waterfall

73’s Jay

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2 Responses

  1. Bill KH6OO says:

    I’m going to Christmas Island in October and was looking for this very thing. How to sync the clock with no internet. We hope to do some jt9 and jt65 look for us. T32DX
    73’s, bill kh6oo

  2. Jay Duthler says:

    Wonderful Bill I am glad it was of use to you. I will look for you on the dates in Oct.

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