LCR Impedance Viewer for Picoscope+Keysight+R&S Bode Plot Data (open source)

[_Wim_]

Wim,

Thanks for the wonderful job you did, especially with the cursor and using FRA4PS as input works fine for me.
I have a point to mention.
In the image showing the impedance, the program also shows a phase. However this is the phase that belongs to the Gain.
In the Image below I show the difference phase that belongs to the impedance.

Hans

Thanks for spotting this  . Corrected version is attached to first post. In the calculations I always used the phase in radians (which was correct), but converted to degrees from the measured phase instead of the phase from the DUT, exactly like you said.

[Hans Polak]

Yep, it's working all right.

Hans

[_Wim_]

Yep, it's working all right.

Hans

Great! Hopefully in the next couple of months I will have some more time to add features like calibration and calculation...

[_Wim_]

Hi Wim,

I have used FRA4 quite a lot on and of since it was released. So yours is a really nice contribution to the tools for Picoscope,
expanding on the usability !

As for Hans in the Previous post I can't get the included measurement application to work. See attached file.

I think I found a solution for the X64 problem. Updated version in first post.

[Hans Polak]

It works like a charm, nice with this extra settling time and overlaying measurements on top of each other, great job.
The only very very small thing is that you have to start measuring twice.
The first time it contacts the Picoscope and after that you have to press measure again, not very important.

Hans

[_Wim_]

The only very very small thing is that you have to start measuring twice.
The first time it contacts the Picoscope and after that you have to press measure again, not very important.

Next to the button "abort measurement" you have the option to leave the picocontrol screen open. This way you only need a single mouseclick for each measurement (I guess this is what you want).

[Hans Polak]

Wim,
I still noticed a small anomaly. In the Modulus diagram, now having the correct phase, the cursor below the image still gives the phase of the bode diagram.

Then I have a few suggestions concerning noise fighting in noisy pictures, although I have no idea whether or in what way noise fighting is already part of your software Tool.
1) the most simple step would be when testing up to a frequency A, to limit BW of both channels to a BW of 5A or something like that.
The scope's BW in my case of 100mHz, has a noise of 100uV.
When measuring up to 100kHz, BW could be limited to 500kHz, already giving a possible noise reduction of 23dB.
2) Since it is possible to "overlay" several measurements in your program, it would help to reduce noise when they could be averaged.

Kindest regards,
Hans

[_Wim_]

I still noticed a small anomaly. In the Modulus diagram, now having the correct phase, the cursor below the image still gives the phase of the bode diagram.
 

Thanks for spotting this (again). Updated version in first post.

1) the most simple step would be when testing up to a frequency A, to limit BW of both channels to a BW of 5A or something like that.
The scope's BW in my case of 100mHz, has a noise of 100uV.
When measuring up to 100kHz, BW could be limited to 500kHz, already giving a possible noise reduction of 23dB.
 

I directly use the DLL from FRA4Picoscope, and get gain and phase results directly. A good discussion on the noise improvement for FRA4Picoscope can be found here:
https://www.picotech.com/support/topic14311.html?&start=390

2) Since it is possible to "overlay" several measurements in your program, it would help to reduce noise when they could be averaged.
 

Yes, this is on my todo list, but a little more work than simple bug fixes, and currently not so much spare time and too many other projects.

[Hans Polak]

Wim,
Thank you for the link. As I found out, there are several paramaters that can be used to reduce noise, that was very helpful.

If have another suggestion. In your Reactance plots, you are using positive and negative values, just as they are calculated.
In all Network Vector analyzers and in Spice, the absolute value of these imaginary numbers are displayed, giving the  image almost twice the resolution and a sharp transition at the point of Fres, also quite useful.
See attachment as an example.

Hans

[_Wim_]

Wim,
Thank you for the link. As I found out, there are several paramaters that can be used to reduce noise, that was very helpful.

If have another suggestion. In your Reactance plots, you are using positive and negative values, just as they are calculated.
In all Network Vector analyzers and in Spice, the absolute value of these imaginary numbers are displayed, giving the  image almost twice the resolution and a sharp transition at the point of Fres, also quite useful.
See attachment as an example.

Hans

Thanks for this suggestion, I was not aware it is commonly done different (have yet to find an affordable VNA). I will implement this in the next version.

[2N3055]

I think reactance sign is also very useful.

[_Wim_]

If have another suggestion. In your Reactance plots, you are using positive and negative values, just as they are calculated.
In all Network Vector analyzers and in Spice, the absolute value of these imaginary numbers are displayed, giving the  image almost twice the resolution and a sharp transition at the point of Fres, also quite useful.
 

I think reactance sign is also very useful.

I have added a “preferences” window under the edit menu, this way the user can choose the plot options (I expect some more options will come in the future). So both can have it your way 

As always, updated version in first post.

[2N3055]

If have another suggestion. In your Reactance plots, you are using positive and negative values, just as they are calculated.
In all Network Vector analyzers and in Spice, the absolute value of these imaginary numbers are displayed, giving the  image almost twice the resolution and a sharp transition at the point of Fres, also quite useful.
 

I think reactance sign is also very useful.

I have added a “preferences” window under the edit menu, this way the user can choose the plot options (I expect some more options will come in the future). So both can have it your way 

As always, updated version in first post.

You're just awesome!!

All the best,
Sinisa

[Hans Polak]

Absolutely perfect addition with the positive reactance.
Thank you.

Hans

[apate26]

Hello Wim
 Thanks for the help but I don't see any installation or upload option, How can I use this? Where should I upload the excel files to see the graphs as you showed?
Thanks
Avi

[_Wim_]

Hello Wim
 Thanks for the help but I don't see any installation or upload option, How can I use this? Where should I upload the excel files to see the graphs as you showed?
Thanks
Avi

First post of this thread contains the files for download. Program does not need installation, running the executable is all that is required.

[KlausKragelund]

Hi

Great tool. Been trying a couple of components out, works fine. But it has problems with range due to the fixed reference resistor

Have you considered if one added a USB controlled relay board to switch in different reference resistors over the range?

Regards

Klaus

[_Wim_]

Considered, yes. But because I did not need this often, never implemented that. Also, it would then require others users to make the same hardware,  which I consider a disadvantage also.

It has been a long time since I even looked at this. As with many of my projects, at some point other interesting subject takes over before a project is really finished (I intended to allow for some calibration routines also, but never got around doing that).

Currently no further development is planned, but maybe someday. All source code is available however, so feel free to add or modify as much as you want.

[Hans Polak]

Hi Wim,

I'm using your excellent FRA Imp Viewer quite a bit.
I still  have a wish high on my list.
When starting the program, the value of the series resistor has to be specified.
However there are also probe tips attached to both sided of this resistor.
The A channel side plays no role, but the probe's capacity on the B channel becomes part of the network and interferes with the measurement.
That's why I always have to go to LTSpice trying to simulate a circuit giving the same characteristics including the capacity of the probe tip, to finally remove this capacity and get the real data for the DUT.
You can imagine that that's quite a job.
So it would be great if your program not only asked for the series resistor, but also for the capacity of the Channel B probe.

Kindest regards,
Hans

[_Wim_]

Hi Wim,

I'm using your excellent FRA Imp Viewer quite a bit.
I still  have a wish high on my list.
When starting the program, the value of the series resistor has to be specified.
However there are also probe tips attached to both sided of this resistor.
The A channel side plays no role, but the probe's capacity on the B channel becomes part of the network and interferes with the measurement.
That's why I always have to go to LTSpice trying to simulate a circuit giving the same characteristics including the capacity of the probe tip, to finally remove this capacity and get the real data for the DUT.
You can imagine that that's quite a job.
So it would be great if your program not only asked for the series resistor, but also for the capacity of the Channel B probe.

Kindest regards,
Hans

Hi Hans,

To do something useful with the input capacitance, I would also need the calibration calculations (which are currently not included in the current version of the software, I never got around doing that). This would require a major update, which is currently not planned.

Source code is however available, and visual studio can be downloaded for free. So it should be feasible to implement this change yourselves. If you have questions about parts of the source code, you can post them here, I will try to help you further, but for the moment, I will not be making any big changes myself.

Best Regards,

Wim

[Hans Polak]

Hi Wim,

Thanks for replying so rapidly.
Two questions:

1) What do you mean with calibrations calculations. Would this be to assess the load of the probe and to verify the value of the used measuring resistor ?
I won't need all this.

2) Since I'm not a programmer would it help when I provide you with the math, where the probe's capacity is now also part of the equation, to calculate the DUT's exact impedance, inductance and capacitance ?

Kindest Regards,
Hans

[_Wim_]

1) What do you mean with calibrations calculations. Would this be to assess the load of the probe and to verify the value of the used measuring resistor ?
I won't need all this.

Yes, this is what I meant

2) Since I'm not a programmer would it help when I provide you with the math, where the probe's capacity is now also part of the equation, to calculate the DUT's exact impedance, inductance and capacitance ?

That might be an option, but no promises. This thread describes what is currently in the code:
https://www.eevblog.com/forum/testgear/rlc-impedance-viewer-for-picoscope-bode-plot-data/msg2238570/#msg2238570

The actual part of the code that does the calculations is here:
https://github.com/WimHuyghe/FRA-Impedance-Viewer/blob/master/FRA_IMP/FRAResult.cs

It should be fairly readable even for a non programmer. Please that this into account when describing the update in the math. Adding an additional input parameter to the GUI is no issue for me, so that can be done easily.

[Hans Polak]

O.K. I'll provide the math, then we see what can be done.

Regards,
Hans

[Hans Polak]

Wim,
Before going into mathematical detail, may I ask you how many bits are used from Picoscope's options.
My Picoscope 5243B has various bit depth settings from 8 bits to 16 bits.
I don't know whether this is an option that your software can influence, bit more bits will of course result in more accurate results, especially when calculating a capacity.

Hans

[_Wim_]

Wim,
Before going into mathematical detail, may I ask you how many bits are used from Picoscope's options.
My Picoscope 5243B has various bit depth settings from 8 bits to 16 bits.
I don't know whether this is an option that your software can influence, bit more bits will of course result in more accurate results, especially when calculating a capacity.

Hans

My software uses the data obtained from FRA, I would need to check his source code. But I would guess max resolution is used, but I am not sure.