> Björn, > > On 05/03/2012 12:30 AM, [email protected] wrote: >> Magnus, >>>> >>>> Tbolt PRS10A PRS10B >>>> 1pps --> PPSIN >>>> PPSOUT --> PPS IN >>>> >>>> PRS10A slowly following the Tbolt (PRS10A PT8) >>>> PRS10B "quickly" following the PRS10A (PRS10B PT0) >>>> >>>> Ok? >>> >>> Yes, but if this is a free-running thunderbolt (I think you said >>> something about that) then PT8 will be a bit slow. For a tracking >>> thunderbolt PT8 may work, even if it takes time for it to track in. >> >> No a GPS locked Tbolt. > > Thanks for that clarification, I am obviously a bit tired. > >> A free-running Tbolt was just an example of a very >> low noise 1PPS source, where I would find it useful to have a "PT-1" >> bias >> calibration mode bypassing the PLL, and moving the PPSOUT directly with >> the PPSIN. > > So this does not suffice?: > > Page 33: > "When provided with an accurate and stable 1pps source, the unit will > automatically align its 1pps output to the 1pps input and then adjust > the frequency of the rubidium reference to maintain the alignment over > time." > > Page 17: > "After receiving 256 consecutive "good" 1pps inputs, the 1pps pulse > delay is set to the last of the 256 time-tag values." > > I interpret this as this: > > When the 256s PPS has been approved, the last-time-tag is used to adjust > the output delay such that the output signal is aligned, within the > precision of the time-offset value. > > Then, the PLL is running. Either the output delay is not shifted and > only the PPS alignment is done on approval, or it is updated in the > background. The text only supports the former explicitly, but it would > be nice to verify if it is either of these. > > Doing phase-jump of PPS like this on start-up is expected. I've even has > a measurement on it somewhere.
It is surely working alright in the long run. I am not convinced it is appropriate for applications where you fire up the PRS for a few hours and then do a few hours of measurements. Even if it jumps the 1pps, early on the PLL will still be 100s of ns away from its reference. There should be a better way to make this, than how I run the PRS... -- Björn _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
