In the matter of lifetime (outside of MTBF issues), is it correct that Rb has a built-in life limiting mechanism (the lamp wears out), where Qz does not? If so, Rb oscillators will eventually fail but one might hope a Qz oscillator may not.
Didier Tom Van Baak wrote: >> Hello folks, >> >> i like to play the bad boy again: My claim is >> >> a) that for most of us a GPSD Rb is of little to no >> use compared to a good GPSD xtal oscillator >> > > Ulrich, > > That's a rather general statement, but I understand what > you mean. Consider, instead of a bold general assertion > which can be disproved with a single counter-example, > a simple list of advantages of quartz vs. rubidium. Then > let the user decide which is appropriate for their unique > application. > > There's more to a GPSDO than its ADEV. For example, > > Warm-up time -- > Many Rb will lock in 5 minutes, typically. Some Qz > take much longer to get on-frequency from cold start. > This can simplify the initial loop locking algorithm. > > Power consumption -- > Probably Qz-based GPSDO have much lower power > consumption than Rb. > > Physical size -- > I would guess most Qz GPSDO are smaller than Rb > GPSDO. One could argue that the Casio GPS wrist > watches are a type of miniature GPSDO! > > Hold-over performance -- > For mid- to long-term, Rb is vastly superior to Qz; > most Rb have daily drift rates 100x better than Qz. > > Stand-along performance -- > Without GPS lock, a free-running Rb can be trusted > to be orders of magnitude more accurate than Qz. > > Environmental -- > Is it the case that Rb is less sensitive than Qz to > extreme environments? > > Cost -- > As a rule, Qz-based GPSDO are cheaper than Rb. > > Phase noise -- > I'd guess that Qz-based GPSDO could have better > short-term stability and phase noise than Rb. > > Tuning range -- > Could it be that Rb will run for many more years without > coarse adjust than Qz? > > Lock indicator -- > Most Rb give you a signal when frequency lock has > been achieved. > > Mechanical sensitivity -- > Rb GPSDO are much less sensitive to movement and > shock than Qz. If you don't believe me watch what > happens if you simply take your GPSDO and bump it, > or turn it over on your desk. This is especially important > during hold-over when no external correction is present. > > Lifetime -- > Is the MTBF of Qz much longer than Rb due to fewer > parts and simpler design? > > Surplus -- > There are so many cheap telecom Rb out there it is > near irresistible to make a GPSDO out of them. > > You get the idea; feel free to add the ones I missed. > > /tvb > > > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
