Hi Igor!

A few years ago, I have built an Elector electronics frequency counter (freq. range 0.001 Hz to 1.2 GHz, also time measurement etc.) I use it for the calibration of the RTC's based on PCF8583. The accuracy is also true 6 digits in the measuring range.

Now I do it so that I compare the time with the DCF77 clock and therefore set the timebase of the frequency counter.
PCF8583 has 1 second pulse output and there I measure the period where I set to 1.000000 second.

GPS receiver is an interesting solution for me. Can you give me more information about it?

Thank you! Franc