Re: [time-nuts] Disciplining a TCXO
On Fri, 26 Oct 2012 11:46:35 +1100 Tom Harris celephi...@gmail.com wrote: I have been asked the viability of using a vanilla TCXO, with an accuracy of +/- 0.5ppm (+/- 15 secs per year) that is disciplined occasionally (perhaps only once a month) with a GPS module. The application is for an analogue clock, which powers up a GPS module every so often to learn the drift characteristics of the TCXO, which it then compensates to generate indicated time. The TCXO's that I have played with have a very predictable aging characteristic over time, at least in a normal home/office environment. Hmm... The feasability of this depends a lot on your temperature variations and the TCXO. If you have a nearly constant temperature, then the aging will dominate. If you don't have constant temperature, then the semi-random variations due to the temperature correction errors will make it hard to really predict what's going on. Yes, you can filter out a long term average, but nothing says that this will be the same for the next measurement period if it's dependend on the temperature variations. Modeling those errors is difficult and not realy for the faint of heart, even if you know what type of frequency correction is used. For a general TCXO it gets very tedious to calculate. Of course, if you need only a crude accuracy, then a simple average error correction might be enough. Attila Kinali -- 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.
[time-nuts] Disciplining a TCXO
Greetings, I have been asked the viability of using a vanilla TCXO, with an accuracy of +/- 0.5ppm (+/- 15 secs per year) that is disciplined occasionally (perhaps only once a month) with a GPS module. The application is for an analogue clock, which powers up a GPS module every so often to learn the drift characteristics of the TCXO, which it then compensates to generate indicated time. The TCXO's that I have played with have a very predictable aging characteristic over time, at least in a normal home/office environment. -- Tom Harris celephi...@gmail.com ___ 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.
Re: [time-nuts] Disciplining a TCXO
Hi If you want to dig into some papers, the RBXO (rubidium and OCXO) is essentially the same thing. Bottom line: As long as aging + repeated temperature is the dominant effect, it works fine. As soon as you get a temperature transient - not so much. Worst case is when the temperature delta happens right after the GPS shuts down. Bob On Oct 25, 2012, at 8:46 PM, Tom Harris celephi...@gmail.com wrote: Greetings, I have been asked the viability of using a vanilla TCXO, with an accuracy of +/- 0.5ppm (+/- 15 secs per year) that is disciplined occasionally (perhaps only once a month) with a GPS module. The application is for an analogue clock, which powers up a GPS module every so often to learn the drift characteristics of the TCXO, which it then compensates to generate indicated time. The TCXO's that I have played with have a very predictable aging characteristic over time, at least in a normal home/office environment. -- Tom Harris celephi...@gmail.com ___ 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. ___ 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.
