[time-nuts] Good references on holdover?

Attila Kinali attila at kinali.ch
Fri Feb 6 08:58:21 EST 2015


On Fri, 6 Feb 2015 10:21:08 +0100
Javier Serrano <javier.serrano.pareja at 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


More information about the time-nuts mailing list