Hi, I just read [1] and stumbled over a small detail in figure 1, which compares the stabilities of various frequency standards:
The stability of active hydrogen masers is higher than the passive ones for short and medium term taus. But for long term, the active maser has a higher variation than the passive. I thought that the long term drift of the hydrogen maser was mostly due to changes in the wall coating (thus changing the wall shift) and temperature dependent variations of the cavity. These two variations should be the same for both passive and active masers. Yet, their long term stability shows a dramatically different behaviour. Can someone explain where this difference comes from or can point me to documents/papers/books that might explain it? Thanks in advance Attila Kinali [1] "An Introduction to Frequency Standards", by Lewis, 1991 http://www.nist.gov/calibrations/upload/ie79-7.pdf http://ieeexplore.ieee.org/iel1/5/2781/00084969.pdf (better quality, but paywall) -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.