I’m presently using TARDIS 2000 to keep the time on the beacon monitoring PC syncronised to an internet time source. This program has some really useful feaures but not all of them are well documented. Whilst it may not be as accurate or have all the facilities or nanosecond accuracy of a real unix-based NTP server it is more than adequate for the average PC user. Important If you are using Windows 2000 or WIndows XP then you need to ensure that the Windows time service is disabled in the control panel as TARDIS replaces this (as mentioned in the TARDIS manual).
As not everyone is lucky enough to have a permanent internet connection I’ve put together a few notes about how TARDIS can be used as a time decoder for the MSF time code signal broadcast on 60kHz. It may also work with the DCF77 and other signals, I’ll update as I find out.
MSF Clock Decoder
I’ve built several MSF and DCF77 clock decoders using modules from Maplin and other sources. For a good design and other useful information I recommend reading Jonathan Buzzard’s pages. If you want a DCF77 module he can supply them. I’ve used these modules for several NTP server applications using the Network Time Protocol distribution running on the FreeBSD operating system. This provides a time source to Windows networks where a connection to the internet is not possible.
As the Maplin modules (stock codes: MK68Y receiver, MK72P ferrite rod aerial) are rather expensive and usually out of stock I decided to explore other (cheaper) alternatives). I found several cheap clocks that use MSF or DCF77 modules for under ten pounds and eventually bought an Oregon Scientific model RM913TCN (Argos ref 256/9594).
I carefully removed the module from the clock as shown in the pictures below. I then built a simple interface and enclosed the completed bits in a small ABS box.
MSF module after removal:
Connection points for interface:
Finally, the circuit of the interface. Note that there should be a diode (1N4148 or equivalent) in-line with the DTR conection, anode to DTR pin. No fancy CAD software here yet so I’ll re-draw the circuit just as soon as I remember where I left my pencil…
MSF Clock Configuration
TARDIS can be configured to use the raw MSF time code which is available from the output of various receiver modules. To use this code, add a TARDIS timeserver with the protocol set to serial radio clock. Set the COM port to your PC’s port where you will plug in the module interface. I’ve already configured mine in the example below, and with the MSF clock selected as the preferred time source and highlighted the status display at the top of the screen should count the clock pulses at 1 second increments. If it appears to count too fast it means your MSF signal is noisy and you need to re-locate your clock module.
Add a new server:
When you have completed this you might like to configure TARDIS to log some details to a logfile:
If you already have TAIL.EXE on your system to trim your beacon logfiles then you can use tail -f to view the tardis logfile as it updates:
If you’d rather use a freeware alternative instead of registering Tardis then take a look at Alan G4ZFQ’s MSFRX page. Alan’s interface has a few more parts than mine including a LED to indicate the MSF signal.