MSF Clock Receiver with Ferrite Aerial available from Maplins at a ridiculous price

Home made weather proof casing made out of plastic conduit

Finished article after 3 years outside (this was used on the original tracker)

This shows the Receiver o/p wave form at the minute Epoch (500mS low) followed by the first 4, second pulse.

The software in the PIC Chip detects the falling edge each second pulse waits 150ms and samples the level of the signal this is the Clock data then samples again a further 100ms after that and this is the Parity Data. I don't use the Parity data. The clock data is shifted into a s/w shift-register. the last 8 seconds (51-59) of the minute the code 01111110 is transmitted in the Clock Data bits and I look for this and on the next second falling edge the Time is valid... To ensure I have the received the data correctly I store the minutes data and check the new minutes data is the same +1min. after this has happend 3 times I update the system clock. More data on MSF available from http://www.npl.co.uk/time/msf/