DMTD Tutorial

[tkamiya]

Actually no....  in my setup, it's rather cumbersome to do it that way.

I see the jumps in exported frequency data.  From 67.3 to 67.8 second, I see frequency going back and forth.  Oddly enough, there is no such jumps in phase data, unwrapped or otherwise.

[thinkfat]

Actually no....  in my setup, it's rather cumbersome to do it that way.

I see the jumps in exported frequency data.  From 67.3 to 67.8 second, I see frequency going back and forth.  Oddly enough, there is no such jumps in phase data, unwrapped or otherwise.

What I find quite odd is the number of jumps in the unwrapped phase data is about double the wraps you have in the original phase data.

[edpalmer42]

This is interesting....

Not unexpected, this is why you see the jumps in the frequency difference graph. They must come from somewhere and a frequency jump must have a corresponding phase change.

PS: While we're at it, "Ctrl-c" in TL will create a screenshot of the currently displayed graph and store it in the clipboard. You can "paste" it into Explorer to save it and attach it to a posting. Must be way easier than taking actual "screenshots" with a camera and downloading the photos to post them.

Or just use File -> Save image or .TIM file -> Save as type -> Image files (*.PNG)

I refuse to try and figure out those blurry photos.

[tkamiya]

Sure.  If you don't like the images, by all means....  I just wanted to give an idea of what I'm seeing.

Concerning number of shifts, that may be because the slope is a lot steeper this time.  I didn't do as good of a job as before having frequencies converge.  What I really need to find out is where this is coming from: hardware side or software side.  I would like to dump the counter data to text file first but being GPIB, I don't have a way to do it.  I'll keep playing.  There got to be a reason.  At least it's consistent though, so I have a hope I will eventually find a solution.

[5065AGuru]

Taka,

Here are some examples of how to set up PLOTTER to use data taken with the ProTIC counter.


DUT and REF       Offset         *************PLOTTER SETTINGS***************************
Frequency            used          Nominal frequency      Tau-0/s      Formula to compute new series with
----------------------------------------------------------------------------------------------------------------
10MHz                 1Hz           1.00000000000E+07      1.0                           1.0e-7*x1
10Mhz                10Hz           1.00000000000E+07        .1                           1.0e-6*x1
5MHz                  1Hz            1.00000000000E+07      1.0                           2.0e-7*x1
5MHz                 10Hz           1.00000000000E+07        .1                           2.0e-6*x1

You load the data file into PLOTTER, Make sure your PLOTTER settings are correct, you
click on Series and then "Compute new series from existing".
Put a name or just a single character into the top line and Input the Formula above into the bottom line.
Before clicking on OK I usually highlight and copy the formula. That way on subsequent measurements I don't have to type it in again, just paste it in.
After you click OK you will see another column labeled with you name or character in the upper right
of the screen. Click on the red Column 1 box to eliminate it.
The black phase plot can now be manipulated if required to remove wraps or to select just a portion to plot. Once you are happy click on Time Stability Statistics and select how you want to plot. For instance select data is phase, use powers of 2, and Normal Allan Deviation.
Once your selections have a check mark click Process on the bottom line.
You will now have the AD plot of the selected data.

Cheers,

Corby