On Fri, 6 Feb 2015 10:21:08 +0100 Javier Serrano <javier.serrano.par...@gmail.com> wrote:
> We would like to start working on holdover performance for White > Rabbit [1]. This is a new domain for us. Our main use case is a WR > switch losing its reference because someone disconnects a fiber. We > can have redundancy, but it will take some time for a switch to change > over to another reference. During this time, the oscillator in that > switch will be free-running. We want to minimize the phase drift > during that interval, which we think should be a couple of seconds > maximum. We have never worked on holdover, and I am wondering if we > can do something smarter than the obvious feeding of some constant > voltage to the VCXO, based on averaging during the locked state. Does > anybody know of any good references on holdover? I think you are looking for something like [1]. I think [2] could be also of help, although it's not as good as the Nicholls paper. Zhou's paper [3] seems to be very similar to what Nicholls did (i have not fully read it yet). HTH Attila Kinali [1] "Adaptive OXCO Drift Correction Algorithm", by Nicholls and Carlton, 2004 http://dx.doi.org/10.1109/FREQ.2004.1418510 [2] "A Frequency Model for OCXO for Holdover Mode of DP-PLL", by Hwang, Shin, Han, Kim, 2000 http://dx.doi.org/10.1109/SICE.2000.889649 [3] "Adaptive Correction Method for an OCXO and Investagion of Analytical Cummulative Time Eror Upperbound", by Zhou, Kunz, Schwartz, 2011 http://www.sce.carleton.ca/faculty/schwartz/abstracts/HuiPaperschwartz.pdf -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson _______________________________________________ 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.