[time-nuts] A question from a newbie

Tom Van Baak tvb at LeapSecond.com
Thu Nov 1 21:54:04 EDT 2018


Daniel,

There's simple C code at http://leapsecond.com/tools/adev_lib.c that does ADEV / MDEV / TDEV / HDEV.
A sample ADEV program using that code is: http://leapsecond.com/tools/adev1.htm

There are Python versions on the web if you're into Python and its ecosystem.
If you want a QBASIC version let me know.

The only thing you need to watch out for is that there are two forms of the ADEV formula. The "x" version takes phase difference as input. The "y" version takes fractional frequency difference as input. You can convert one to the other with differentiation or integration.

Since your old GPIB and basic days there are some very nice tools that take all the pain out of ADEV now.
One is Stable32, highly recommended. [1]
The other is TimeLab, also highly recommended, especially if this is your first time doing clock statistics interactively. [2]
Both have extremely well-written and informative documentation, worth reading even if you don't use the programs.

/tvb

[1] http://www.stable32.com/
[2] http://www.ke5fx.com/timelab/readme.htm


----- Original Message ----- 
From: "Daniel H. Pressler" <dpressler at dandydan.net>
To: <time-nuts at lists.febo.com>
Sent: Thursday, November 01, 2018 3:05 PM
Subject: [time-nuts] A question from a newbie


>I was directed to this group when I asked this question of another group.
> However, after reading some of the emails I am a real novice when it comes
> to this stuff.  I worked with cesium and rubidium oscillators as Primary
> Reference clocks in the telecommunication industry.  When I was there I
> wrote a basic program to retrieve phase offset between two signals over GPIB
> from a counter.  The program then calculated frequency accuracy and did some
> Allan Variance calculations.  I am trying to replicate that with an Arduino
> and a simple phase comparator.  I have forgotten the math and I am not smart
> enough to glean it out of the data presented on the internet.  Can someone
> point me to some example programs that will allow me to measure phase offset
> over time and calculate frequency accuracy and do some basic Allan Variance
> calculation.
> 
> 
> 
> Thanks,
> 
> 
> 
> Daniel H. Pressler, KF2HP
> 
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