A signal is transmitted from a clock every 30seconds and rec’d in the code shown , if sends PP. Every minute the “ minutes” figure is updated ( 2x 30sec =1min) .
In the data I look for that “P” and if its there it’s a valid message
I made this so I could see the error in the sending clock over a few days , just quickly knocked it out , but causing a bit of grief ( missing the odd pulse atm now