There is currently a discussion on the time-nuts mailinglis about designing a GPS Disciplined Oscillator (GPSDO). It is by far not the first discussion of this kind and most likely will not be the last. What makes this one stick out, though, is that that Tobias Plüss has put quite a bit of thought effort into the design and it shows. While a GPSDO is not the most difficult electronics a hobbyist or time-nut can build, it is one of those designs where the details matter a lot. A small short-cut taken here, a non-optimal component choice there and a lot of performance is suddenly gone. And it is not easy to see where the critical points are. As quite often when it comes to precision metrology, each and every step has to be carefully evaluated and judged on its merits and demerits.
