[time-nuts] Another "atomic" clock question

Tom Van Baak tvb at LeapSecond.com
Wed Mar 5 18:48:46 EST 2014

I agree with Bob.

For casual use, "hanging bridges" are not really a problem, statistically speaking -- so don't worry.

Yes, you can apply various techniques to reduce/eliminate the rare effect: forced temperature change, forced Vcc change, 2 or 3 or more shared-antenna receivers, modulating phase, frequency, voltage, temperature, etc. But as you spend too much time engineering this uncertain hack you maybe start to wonder if the real solution is just to apply known digital, numerical correction instead of wishful analog cover-up. Been there, done that.

For more serious use, at the tens or unit nanosecond level, the robust solution is simply to apply 1PPS sawtooth correction from the receiver.

This issue comes up every now and then as people gradually transition from casual to serious use. I welcome any hard data or plots that demonstrate the difference among all approaches. There *is* a slight difference for sure. It's just that most people throw in the towel and use sawtooth corrections instead of trying to avoid them and cover up with less deterministic methods.


----- Original Message ----- 
From: "Bob Camp" <lists at rtty.us>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Wednesday, March 05, 2014 3:03 PM
Subject: Re: [time-nuts] Another "atomic" clock question


If you are going to decode and use the sawtooth data out of the receiver, there’s no need to eliminate the hanging bridges. The sawtooth data does that for you already. Put another way, heating the receiver is *harder* than just using the decoded data….


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