Tuesday, July 24, 2012

Free Program for Analyzing Clocks and Oscillators

In this blog post we will look at a free MATLAB program that I created and posted on MATLAB Central for download. The program is called Stability Analyzer 53230A and it provides stability analysis capabilities of clock and oscillator measurements, including Allan and Hadamard Deviation calculations. The "new" program is actually an update to a previous version of Stability Analyzer 53230A that was created over a year ago, but the new version has much more capability. The following is a summary of the program and its capabilities.


Description:
The Stability Analyzer 53230A (2.0) is a free MATLAB program that allows you to analyze the stability of clocks, oscillators, and other signal sources using frequency measurements. The program either inputs / uploads frequency measurements from Agilent’s 53230A universal counter or stored measurements on a CSV file. The program provides the user with a choice of two stability calculations, Allan deviation or Hadamard deviation (both overlapping). The program outputs three plots:
  • Allan or Hadamard deviation plot with optional confidence intervals. 
  • Frequency vs time plot of all measurements 
  • Histogram frequency plot 
All plots provide zoom and pan capabilities as well as the ability to identify a particular plot point. The program is setup and run via a graphical user interface (GUI) and is started from the MATLAB command line. If the 53230A universal counter is used with the program for making measurements then the Instrument Control toolbox is required in your MATLAB package.

Example run:
Below is an example analysis made with the Stability Analyzer 53230A program on a 69.251 MHz oscillator. The gap-free frequency measurements were made with the 53230A universal counter. The measurements were made at a gate time of 10 ms and a total of 5,000 measurements were made for a total measurement time of 50 seconds. The result can be seen below (click to enlarge).


In the Time vs Frequency plot you can see at the measurement gate time (10 ms or 100 Hz) that the dominate noise types seem to be White FM and Flicker FM. From the Overlapping Allan Deviation plot we can see from the slope that from the Tau value of 50 ms to the Tau value of 5 s the oscillator signal is dominated by Random Walk FM noise.

Click here to download the Stability Analyzer 53230A from MATLAB Central

If you are new to stability analysis I recommend the NIST Handbook of Frequency Stability Analysis

Click here for more info on Agilent's 53230A universal counter

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