Sunday, December 21, 2014

Chronoverter: your own MSF time signal

How do you control an MSF "radio controlled" clock yourself, for example from the time signal from a GPS? There are radio time signals around the world for example WWVB in the USA and DCF77 in Germany but in most of the world, including offshore in a boat you can't receive these long wave signals. However most places, must of the time you have GPS. The answer  as I mentioned in an earlier post is a small cheap module called Chronoverter from Unusual Electronics. Now I have one and here are some initial pictures. I might add to this post soon when I get it working.

For discussion of the opposite, decoding the MSF signal, see Dances With Ferrets blog.

Here is the module. The top three pins are 5V signal out and 0V, the bottom thee are the serial line.

I used an old "wall wart" 5.2V power supply. It was not very smooth bot it worked ok. For the serial line I used a StarTech USB to Serial. It has a nice feature that it always comes up as the same COM port or ttyUSB.

I struggled a bit to get it to work on my Ubuntu Linux laptop.  In retrospect that was probably as I was running gpsd and that was grabbing the serial port! There is a dsicussion of how to fix it on this forum. but not tried that. Looks like one needs to change the gpsd hotplug rules. Here is an FAQ explaining why.

I tried my MacBookPro. Looking at /dev/tty* it was clear what appeared when I lugged in the converter so I typed

 screen /dev/tty.usbserial-AH02B6VE 4800 n81

I then had the serial interface to the Chrnoverter and I could set the battery backed clock.

The next step is to feed the RF output to a radio controlled clock. Here is a radio controlled  clock mechanism out of its case so you can see the ferrite antenna. To be continued...



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