Thursday, June 1, 2017

GPS timing for JT modes

After my last post about the Denmark holiday experimental radio activity I got a lot of e-mail if the GPS timing I wanted to make is already working. Strange not many amateurs use GPS timing instead of a NTP internet timing. It is very common with for example the WSPR kits from Hans Summers G0UPL. If you are in the field without a internet connection GPS might do the trick and you get some extras as well. I know many blog readers are eagerly waiting for this post I even got a e-mail from HS0ZBS Kurt who only has a internet connection through his phone. He likes JT modes but has to pay lots of money only to keep his laptop on time, a GPS timing would be perfect for him.

So, I bought a cheap small bluetooth keyring GPS receiver for this task. I researched the minimum requirements for this task and think it is important to have a Sirf3 GPS module chip inside the receiver to have best receiving capabilities. I payed 25 euro for it but I'm certain there are cheaper ones with or without bluetooth. For instance this one on Aliexpress for 15 USD only. Unfortenately I had bad luck as the Li-ion 3,7V 450mAh battery inside was broken. I considered to send it back but that would mean it would take several more weeks to continue experimenting. So I decided to hook it up to an old tablet battery I had on my desk. The GPS was starting now and made connection with sats and with my laptop. Unfortenately my old Windows XP laptop didn't assign COM ports to the bluetooth communication ports automatically, but I solved that manually. Still it didn't show location and didn't sync time. Even a test tool couldn't make a connection. Finally as a last solution I restarted the computer and magically the GPS coms came alive...

I use a time sync program from IZ2BKT which is doing both synchronisation via internet and GPS. The extras and proof it is working are the exact coordinates and WW locator you are in together with the altitude. This is great info for those that are working in fieldday, RaDAR or portable configuration.


Pete said...

Wonderful article. This is what I needed to finally get me to use GPS timing. Thanks, Pete / W6LAW

PE4BAS, Bas said...

Hi Pete, great it has been a help for you. Hopefully you can reproduce my experiment. 73, Bas