Article for the GMDX Digest – Autumn 2019 edition         Updated 24th October 2019

What time is it?                                                                                         Chris Tran GM3WOJ

What do you do when you need to know the exact time?  You look at your phone or your watch, or you look at the time on your laptop or iPad etc. All very easy if you have internet connectivity or mobile phone coverage (and if your watch battery has not gone flat)

All right - what do you do if you are on a DXpedition to a remote (Pacific or Scottish) island where there is no mobile phone network and the internet connectivity is patchy – sometimes disappearing completely for hours or days?  Not a problem – most laptop internal clocks only lose or gain a few seconds per day – perfectly OK for logging the DXpedition QSOs – yes?

No – DXpeditions at this low point in the sunspot cycle need to operate FT8 and FT4, both of which modes rely on very accurate timings for the transmit and receive periods.  FT8 transmissions last for 12.64s in a 15.0s period, FT4 transmissions last for 4.48s in a 6.0s period – you cannot use either mode if your PC clock is inaccurate by any significant amount.

If you have internet connectivity, accurate PC timing is easy – just install one of a number of software packages designed to keep your PC clock synchronised to a very accurate online source – two examples of suitable software are Meinberg NTP and Dimension4.  Network Time Protocol (NTP) servers can keep your PC clock accurate to under 0.1s under normal internet traffic conditions.

 

Back to the problem – no reliable internet, no 4G – what can we do?  Let’s turn our eyes to the sky – the Global Positioning System is the answer. The GPS system depends on super-accurate clocks (four in each satellite) hurtling around above our heads – let’s access  that accuracy on our remote island.

 

My first approach turned out to be a dead end. I found software online called ToyNtp 1.2 written by Alex Shovkoplyas VE3NEA (DXatlas, Skimmer, etc).  The Garmin GPS-18x LVC  unit he specified was quite expensive – about £70 – so I decided to build a QRP Labs QLG-1 GPS module kit and see if it would work with the ToyNtp software – it did not!

The photo below shows the QLG-1 module, powered from a +5.0V DC supply.  The supplied ceramic patch antenna (not shown) is very effective, but I fitted the optional SMA socket and used an external powered GPS antenna which improves sensitivity.

The green LED flashes at 1 pulse per second once satellites have been acquired – the serial data output is then connected to a COM port on your PC.

(I’ll now use this module with a QRP Labs ‘Prog Rock’ kit to make a GPS disciplined 10MHz oscillator for my shack.)

                             

I then looked around the internet more carefully and found exactly what I needed.  The software is called GPS2Time and is written by Doug Hunter VK4ADC and made available as freeware – thanks Doug!  Download and unzip this software into a separate directory, where you will see the .exe file and two logfiles will be created (once the software runs for the first time).

I purchased a suitable cheap USB car GPS/GNSS receiver on eBay (£10.99) – I ordered a type G-mouse VK-162 as specified by VK4ADC on his webpage, but the unit that arrived was a U-blox 7 (but labelled G-mouse) – I think they are all similar anyway.  * They are not - there are some fake VK-162s for sale online - see important note below *

                              

This is a much simpler approach – the U-blox 7 plugs directly into a USB port on your laptop/PC and is powered by the USB port. This is really convenient for a DXpedition where carrying extra power supplies, etc. can be difficult.

You need to download and install the drivers for the U-blox 7 – Windows then recognises the GPS module as a new COM port, which you then point the GPS2Time software to.

Here is a screen shot of the GPS2Time software – the GPS receiver is connected on COM11 and receiving 10 satellites with the baud rate is set to 9600. The update time is set to 1 minute, but can be longer of course. As a bonus you get an accurate position and height fix.

                              

I’ve tested this software with three different Operating Systems – Windows XP SP3, Windows 7 Pro 64-bit and Windows 10 64-bit. It works well in all 3 cases, however there are a few things to watch – with W7 and W10 you have to run the software as an Administrator, but with XP I found it only worked if I did not ‘Run as Administrator’. Note - the software won’t run unless you first select a Baud rate with the pull-down menu e.g. 9600 as above - you may also need to delete / refresh some COM ports on your PC.  Important – make sure you have ‘Internet time sync’ switched OFF on your laptop or PC.

Doug VK4ADC has recently written new versions of the software, including an improved version for Windows XP – he e-mailed me this information “That GPS mouse will automatically switch baud rates so while you have used 9600, you can set the software’s baud value to 57600 (or even 115kB) and it all still works. In fact the faster the baud rate then the lower the timing error because the software decodes the GPS’s time stream closer to the Seconds ‘change-over’ point and sets the PC clock closer as a result. The worst case condition is going to be a 1 second inaccuracy but it can be a lot better than that with a high baud rate”.

Happy GPS timing!!                             73    Chris   GM3WOJ                 

GPS2Time software download :   https://www.vk4adc.com/web/software-projects/55-vk4adc-utils/181-gps2time

U-blox 7 driver download  :  https://www.u-blox.com/en/product-resources/property_file_product_filter/14432    Click 'Download software only'

 

UPDATE 24th October 2019 - IMPORTANT -  DO NOT BUY A 'G-MOUSE VK-162' IF IT IS MARKED 'BD&GPS' - these are a Chinese version which do not seem to have any suitable driver software available. (BD refers to Beidou No.1 satellite). Look for a VK-162 which has no marking other than 'G-Mouse'. If the photograph on eBay or wherever shows only the back of the VK-162, don't buy it!  I am testing the eBay 'Returns' process by asking for a refund of what I paid for two of these 'VK-162's which just don't work - one of them is not even detected as a new USB device when plugged in :-( I don't think they are based on the U-blox7, but I may be wrong.

I found the dongle shown in the photo below does work well - it is clearly marked U-blox7 - use a USB extension cable if necessary.

                                   

[ If you are interested in GPS disciplined oscillator control/timing etc. try running this strangely-named software with your U-blox 7 GPS RX  (it can’t control your PC clock) :   http://www.ke5fx.com/heather/readme.htm ]