Rugby MSF Time Signal Decoder for Linux

Summary

These pages describe how to setup a cheap Maplin type radio clock receiver as an accurate time source for a linux computer. They are an adaption of work originally done by Mike Pilsbury. Mike's original notes are contained in the file msf.doc.

DISCLAIMER!!! If you damage your computer by attaching the receiver to it, it is not my fault. Delta Software Services Ltd and David Godfrey accept no liability for any damage or loss caused by the use of the hardware or software described in these pages.

Contents

Building the receiver

The Maplin part number for the kit is LP70 60kHz Rugby Rx price 19.95. I recommend powering it off the p.c.'s power supply and connecting the output to a spare parallel port. The aerial needs to be kept away from any computer screens, which seem to generate most radio interference. You need to give the receiver time to stabilize after powering it up, before trying to tune it.

Downloading the software

The software comes in two gzipped tar files:-

Patching the kernel

Select the appropriate patch for your kernel then:-
        cd /usr/src
        patch -p <...../rugbyMSF/patch_linux-VERSION
        chmod og+r linux/include/rugby.h
Edit the defines in rugby/MDP_stuff.c depending on which input port your receiver is using and rebuild the kernel.

Patching xntpd

Obtain a copy of xntp3.5f (or later). Apply the appropriate patch ...../rugbyMSF/patch-xntp3.5f.

Then from the xntp3.5f directrory, make refconf and select the RUGBY clock, then make, make install to build and install the xntpd daemon.

Create an /etc/ntp.conf file containing something like 

        # The Rugby MSF radio clock
        server 127.127.29.0
And start up the xntpd daemon.

Checking the clock status

xntpd communicates with the decoder via the /proc/msf file. A simple check on the clock status can be obtained by cat /proc/msf. A simple program to format this data (rugby.c) is included.

dave@deltass.co.uk