Frequency Response Analyzer with Bode Plots

[_Wim_]

Just a quick update with some bugfixes:
- incorrect phase was shown in impedance plot (both plot and cursor)
- app did not work on X64 systems (had to force 32 bit mode for the app to make it work).

@Kai, I am still planning to do the calibration, just a bit tied up for the moment, so only had time for these quick fixes so far.

[vahid1661]

Hi all,

I need to measure the consumption power for a coil and a piezo. What is the standard way of doing this using FRA?

Thanks,
Vahid

[_Wim_]

Hi all,

I need to measure the consumption power for a coil and a piezo. What is the standard way of doing this using FRA?

Thanks,
Vahid

You mean expected power consumption at each frequency? If yes, I think the easiest way is to plot the impedance curve by using a series resistance and my impedance viewer app, export this impedance data to excel, and calculate power from there.

If you want to measure consumed power of a period of time (independent of frequency), then something like the Picolog software seems more appropriate were one channel measures the rms current (with a current probe) and another channel the rms voltage. I believe you can add a calculated channel also to display the power directly. But this way it is not possible to differentiate between real and apparent power (no phase info) .

[vahid1661]

Thanks for your reply.

What is "my impedance viewer app"?
How can I download it?

Thanks,

Vahid

[_Wim_]

What is "my impedance viewer app"?
How can I download it?

You can find it here:
topic14311.html?&p=141799#p141728

Source code is available here:
https://github.com/WimHuyghe/FRA-Impedance-Viewer

Some more details are described earlier in this thread and here:
https://www.eevblog.com/forum/testgear/ ... plot-data/

[Hans Polak]

Hi Aaron,

Thank you for the wonderful job you did with FRA4PS.
The more I use it, the more I like it, however concerning noise suppression I have a few questions.
With my 5243B I already use the "noise reject" option which was already a big step forward.
1) I can also choose a "noise reject bandwidth" although results with 100Hz are sometines better as with 10Hz, something that I cannot understand so well.
2) Then there is a "low noise oversampling" whose function is not at all clear, just as "noise reject timebase" and the "purity lower limit".

Maybe it's all to be found in your source code, but that's not exactly my beer.
To get the lowest possible noise in my images, I would be very grateful if you could give any further detail information on these adjustable parameters.

Kindest Regards,
Hans

[hexamer]

Hello Aaron,
It has been a while. I am back in the power supply mode. When we last spoke I was working with version 0.6.1b. I just installed your version 0.6.2b RC4. Could you tell me some of the changes in this latest version. I have a 2208B USB Pico Scope. Thanks / Charles

Hi Charles,

It's mostly bug fixes. The only features added between those versions are:

1) Ability to program a dc offset for the AWG
2) API trace logging to help diagnose issues
3) Support for 5000D series scopes

As far as I can tell none of these affect your scope or the work you're doing, so it's up to you whether you want to bother updating.

Thanks,

Aaron.

[hexamer]

Hi Aaron,

Thank you for the wonderful job you did with FRA4PS.
The more I use it, the more I like it, however concerning noise suppression I have a few questions.
With my 5243B I already use the "noise reject" option which was already a big step forward.
1) I can also choose a "noise reject bandwidth" although results with 100Hz are sometines better as with 10Hz, something that I cannot understand so well.
2) Then there is a "low noise oversampling" whose function is not at all clear, just as "noise reject timebase" and the "purity lower limit".

Maybe it's all to be found in your source code, but that's not exactly my beer.
To get the lowest possible noise in my images, I would be very grateful if you could give any further detail information on these adjustable parameters.

Kindest Regards,
Hans

Thank you for the feedback, Hans.

A few posts ago, I had tried to clarify many of these. You might find some useful explanation here: topic14311-255.html#p121551

Some additional clarifying details for your questions:

1) "low noise oversampling" does not apply to noise reject mode
2) "purity lower limit" is not implemented yet. Purity is a measure of the energy detected by the DFT vs total signal energy (excluding dc energy). Once implemented, the concept is that if the purity measure is too low, additional mitigations could be activated: retrying, increasing the stimulus signal, etc. Purity is computed now, but is only reported in time domain diagnostic plots.

As for why you sometimes experience more noisy results with narrower bandwidth, I wonder if it's because of some of the more recent discussions here regarding DDS implementation. You could try the "extra settling time" option to determine that. You could also turn on time domain diagnostic plots to visualize what noise source is present.

Thanks,

Aaron.

[kirankanchi]

Hello,
I have a PICOSCOPE 5444B and 2207B, FRA works like a charm on the 2207B but limited to 1Mhz. Can this limit be lifted ? what are the limiting factors ? I am sorry for my ignorance, i am new here .

I tried with FRA with my PICO 5444B but i get error : Error: Unable to initialize device with serial number FX923/063.

Is the max frequency limit going to increase with 5000 series ?

Kudos for the tool!

Thanks
Regards
Kiran Kanchi.

[hexamer]

Hello,
I have a PICOSCOPE 5444B and 2207B, FRA works like a charm on the 2207B but limited to 1Mhz. Can this limit be lifted ? what are the limiting factors ? I am sorry for my ignorance, i am new here .

I tried with FRA with my PICO 5444B but i get error : Error: Unable to initialize device with serial number FX923/063.

Is the max frequency limit going to increase with 5000 series ?

Kudos for the tool!

Thanks
Regards
Kiran Kanchi.

Hello Kiran,

Thank you for your interest in the FRA application. I appreciate the feedback.

The limitation of 1 MHz for the PS2207B is a limitation of the scope. See spec excerpt from the website:

The PS5444B supports up to 20 MHz.

As far as I know there is no compatibility issue with the 5444B. My main scope is a 5444A, so the application does often get tested on that family. Could you help me diagnose the issue?

1) What version of the application are you using?
2) Did you install the latest 32-bit SDK?
3) Please turn on all logging (Tools -> Settings -> Log Verbosity, check all boxes) and attempt to connect to the scope and report back what the log says.

Thanks,

Aaron.

[Andreas_]

Hello Aaron,

again me with a question for improvement.
I am testing my 0.1 .. 10 Hz Low Noise amplifiers with a PS5444A.
When I try this frequency range with 24 steps/decade I get several
duplicate frequencies. Obviously the minimum resolution of the PS5444A is 0.04 Hz from frequency step to frequency step.
Would it be possible to skip the duplicate steps in the low frequency range?
Besides a more beautiful diagram without dents, this would also speed up the calculation.

with best regards

Andreas
----------------------------------------------------------
Status: Starting frequency step 1 (0.093 Hz)
Status: Starting frequency step 2 (0.093 Hz)
Status: Starting frequency step 3 (0.140 Hz)
Status: Starting frequency step 4 (0.140 Hz)
Status: Starting frequency step 5 (0.140 Hz)
Status: Starting frequency step 6 (0.140 Hz)
Status: Starting frequency step 7 (0.186 Hz)
Status: Starting frequency step 8 (0.186 Hz)
Status: Starting frequency step 9 (0.233 Hz)
Status: Starting frequency step 10 (0.233 Hz)
Status: Starting frequency step 11 (0.279 Hz)
Status: Starting frequency step 12 (0.279 Hz)
Status: Starting frequency step 13 (0.326 Hz)
Status: Starting frequency step 14 (0.326 Hz)
Status: Starting frequency step 15 (0.373 Hz)
Status: Starting frequency step 16 (0.419 Hz)
Status: Starting frequency step 17 (0.466 Hz)

[hexamer]

Hello Aaron,

again me with a question for improvement.
I am testing my 0.1 .. 10 Hz Low Noise amplifiers with a PS5444A.
When I try this frequency range with 24 steps/decade I get several
duplicate frequencies. Obviously the minimum resolution of the PS5444A is 0.04 Hz from frequency step to frequency step.
Would it be possible to skip the duplicate steps in the low frequency range?
Besides a more beautiful diagram without dents, this would also speed up the calculation.

with best regards

Andreas
----------------------------------------------------------
Status: Starting frequency step 1 (0.093 Hz)
Status: Starting frequency step 2 (0.093 Hz)
Status: Starting frequency step 3 (0.140 Hz)
Status: Starting frequency step 4 (0.140 Hz)
Status: Starting frequency step 5 (0.140 Hz)
Status: Starting frequency step 6 (0.140 Hz)
Status: Starting frequency step 7 (0.186 Hz)
Status: Starting frequency step 8 (0.186 Hz)
Status: Starting frequency step 9 (0.233 Hz)
Status: Starting frequency step 10 (0.233 Hz)
Status: Starting frequency step 11 (0.279 Hz)
Status: Starting frequency step 12 (0.279 Hz)
Status: Starting frequency step 13 (0.326 Hz)
Status: Starting frequency step 14 (0.326 Hz)
Status: Starting frequency step 15 (0.373 Hz)
Status: Starting frequency step 16 (0.419 Hz)
Status: Starting frequency step 17 (0.466 Hz)

Andreas,

Thank you for reporting this. I had never seen it before. I will work on fixing it in the next release, which I hope to make very soon. I'll just plan on removing the dupilcates from the frequency list before running the FRA.

Thanks,

Aaron

[Andreas_]

Hello Aaron,

thats fine for me

thanks

Andreas

[Andreas_]

I tried with FRA with my PICO 5444B but i get error : Error: Unable to initialize device with serial number FX923/063.

Hello,

Something similar also happened to me when I had running the PicoScope 6 software in the background.

with best regards

Andreas

[hexamer]

Hello Aaron,

thats fine for me

thanks

Andreas

Andreas,

I've made this fix and incorporated into a new released version: https://bitbucket.org/hexamer/fra4picoscope/downloads/FRA4PicoScope%200.6.2b.msi"

Please let me know how this works out.

Thanks,

Aaron.