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Muyltiple Time Interval Capture

To measure the stability of an oscillator, you normally run a Time Interval Counter between the Oscillator Under Test and a Reference Oscillator. What do you do when you do not have a Reference Oscillator that you know is better than the one you want to measure?

You use the “three-corner-hat” method: you compare three oscillators 2 by 2 and you can then determine by computation which is the best one and evaluate the performance of the others compared to this one.

Here is a thread about what John Ackerman did to do that.

If anybody's interested, I have a perl script (running under Linux, using the linux-gpib tools) that controls a 59307A and HP 5334A to do long-term logging of four PPS sources against each other.

It takes a 100 second average of each PPS source sequentially; I end up with six log files, each with a tau of 600 seconds: CS1-GPS, CS2-GPS, RB1-GPS, CS1-CS2, CS1-RB1, and CS2-RB1.

If anyone's interested, I'd be happy to make that program available, though it's not polished up for distribution.

The data files from this program are the basis for phase and adev plots at http://www.febo.com/plots/ which are updated hourly. The software that generates those plots is called stable-stats and is available for download at http://www.febo.com/time-freq/tools/. (Unfortunately, at the moment the plots are out of date as we had a power failure last week and I don't have the clocks reset yet; that's a project for this weekend.)


precision_timing/multiple_time_interval_capture.txt · Last modified: 2013/01/08 19:00 (external edit)
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