Frequency Response Analyzer with Bode Plots

Post discussions on applications you are writing
Post Reply
lech226@gmail.com
Newbie
Posts: 0
Joined: Wed Nov 13, 2019 7:59 am

Re: Frequency Response Analyzer with Bode Plots

Post by lech226@gmail.com »

Hi Hexamer.
Have a nice day.'Thank you very much for your clear description
I got it.That's is very mean to me.
I would to buy one for my purpose.
Thank you.

igorfier
Newbie
Posts: 0
Joined: Wed Dec 18, 2019 7:15 pm

Re: Frequency Response Analyzer with Bode Plots

Post by igorfier »

Dear Aaron,

I just stumbled upon your very nice application while looking for ways to implement FRA functionality to my 2204A. It installed just fine in W10 x64 and initialized my scope upon startup.
I am now trying to measure simple circuits such as a resistor and capacitor in parallel, but I can't get any meaningful data. I suspect I didn't quite get the way the leads should be connected.
Here's what I'm doing, based on the posts I found about the same subject:

- At one end of the RC: inner bayonet of the CH-A BNC and inner bayonet of the AWG;
- At the other end of the RC: inner bayonet of the CH-B BNC and outer shield of the AWG.
- The outer shields of the CH-A and CH-B BNCs are left floating.

What am I doing wrong?
Thanks in advance for your answer and your time.

Best regards,
Igor Fier

kaimex
Newbie
Posts: 0
Joined: Tue Feb 26, 2019 4:29 pm

Re: Frequency Response Analyzer with Bode Plots

Post by kaimex »

Hi Igor,

with Channel B input connected to the shield of the AWG you are shorting that input to ground.
The shields are all connected.
With channel A connected to the AWG output and your RC-circuit connected between the A and B inputs you get a voltage on input A that is Z_RC/(Z_RC+RoutAWG)*UoutAWG.
I have forgotten the exact Rout, guess it was somewhere around 600...700 Ohm.
When your RC-circuit has a very high impedance compared to that, you will get almost the full AWG output voltage. If Z_RC is very small compared to RoutAWG, you will get almost nothing.
You will get something meaningful, if Z_RC is not to far away from Z_out.
If Z_RC is very high, you have also to consider the input impedance of channels A & B of ~ 1 MOhm.

Regards Kai

STMN
User
User
Posts: 6
Joined: Thu Aug 29, 2019 8:36 am

Re: Frequency Response Analyzer with Bode Plots

Post by STMN »

Hello,

many thanks for that usefull tool, is that possible to change X axis to linear view? I intend to measure the frequency response of a IF filter, please see the attached file here:
https://www.picotech.com/support/topic40059.html?&p=143399#p143399

Best Regards

hochfrequenz
Newbie
Posts: 0
Joined: Sat Nov 03, 2018 7:14 pm

Re: Frequency Response Analyzer with Bode Plots

Post by hochfrequenz »

Hi there,
would like to install the FRA Bode-plot- program. The instructions in the wiki are out of date. Can someone explain what I have to do. I'm really overwhelmed. I have attached a screenshot of the download page.

WIN 10 64bit, Picoscope 2205A

Marco Schramm
Attachments
Picoscope  FRA  WIKI  downloads.jpg

ts8051
Newbie
Posts: 1
Joined: Wed Feb 12, 2020 7:00 pm

Re: Frequency Response Analyzer with Bode Plots

Post by ts8051 »

Hello, I downloaded your application for pico 3000 oscilloscope fra4picoscope and it is working properly in my MAC under VMware. Please let me know if there is a possibility to compile it for use in MAC OS. I live in Athens, Greece

hexamer
Advanced User
Advanced User
Posts: 0
Joined: Tue Aug 12, 2014 10:09 pm

Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

STMN wrote:
Tue Jan 28, 2020 12:12 pm
Hello,

many thanks for that usefull tool, is that possible to change X axis to linear view? I intend to measure the frequency response of a IF filter, please see the attached file here:
https://www.picotech.com/support/topic40059.html?&p=143399#p143399

Best Regards
If you strictly wanted to plot in linear view, you could export the data and re-plot it. But I assume you probably actually want to have the frequency samples in linear mode too. Unfortunately the application isn't currently designed for that use case, but I do have plans to do that some day.

hexamer
Advanced User
Advanced User
Posts: 0
Joined: Tue Aug 12, 2014 10:09 pm

Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

hochfrequenz wrote:
Sun Feb 02, 2020 6:36 pm
Hi there,
would like to install the FRA Bode-plot- program. The instructions in the wiki are out of date. Can someone explain what I have to do. I'm really overwhelmed. I have attached a screenshot of the download page.

WIN 10 64bit, Picoscope 2205A

Marco Schramm
Hi Marco,

First, you should download and install the latest version of the 32 bit Pico SDK: https://www.picotech.com/download/software/sr/PicoSDK_32_10.6.13.97.exe

Then you should be able to download and install the latest version of the FRA app from the downloads page. Here's a direct link: https://bitbucket.org/hexamer/fra4picoscope/downloads/FRA4PicoScope%200.6.2b.msi

Let me know if you run into issues.

Thanks,

Aaron.

hexamer
Advanced User
Advanced User
Posts: 0
Joined: Tue Aug 12, 2014 10:09 pm

Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

ts8051 wrote:
Wed Feb 12, 2020 7:14 pm
Hello, I downloaded your application for pico 3000 oscilloscope fra4picoscope and it is working properly in my MAC under VMware. Please let me know if there is a possibility to compile it for use in MAC OS. I live in Athens, Greece
The UI portions of the FRA application are very Win32 API specific. Even the "backend" software is probably not perfectly portable. So, to make it portable and compile it all for MAC would be a really big undertaking.

I'm glad to hear you can run it in a VM. I've had pretty good success with that approach too as it's the only realistic way I can still test for Windows XP compatibility.

berprang
Newbie
Posts: 0
Joined: Mon Mar 30, 2020 1:28 am

Re: Frequency Response Analyzer with Bode Plots

Post by berprang »

Thank you for the very nice software. I was able to use the software without any problem.

I have a request if it is possible. I works in the area where i need to measure the harmonics of signal. Could you put some options in the DFT process, whether to pick the signal with the same frequency of the internal function generator or the multiple number of the frequency (harmonics).
Thank you

hexamer
Advanced User
Advanced User
Posts: 0
Joined: Tue Aug 12, 2014 10:09 pm

Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

berprang wrote:
Mon Mar 30, 2020 1:38 am
Thank you for the very nice software. I was able to use the software without any problem.

I have a request if it is possible. I works in the area where i need to measure the harmonics of signal. Could you put some options in the DFT process, whether to pick the signal with the same frequency of the internal function generator or the multiple number of the frequency (harmonics).
Thank you
Thank you for the kind feedback. I am curious about your use case. Can you elaborate on where such an analysis is useful? Also, are you interested in just specific harmonics or the combination of all higher order harmonics?

Depending on which harmonics you are interested in, you may be use the low noise oversampling setting to get what you want. E.g. by setting the oversampling value to 2 (exactly at Nyquist), the DFT would pick up all the higher order odd harmonics.

hexamer
Advanced User
Advanced User
Posts: 0
Joined: Tue Aug 12, 2014 10:09 pm

Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

External Signal Generator Part 1:

Since it's a top request, and I recently developed a need myself, I started work on a feature to use an external signal generator. A first version of that work is nearly ready.

When I first considered doing this, I felt that it needed to be done in a way that would not be intrusive to the typical user who would most likely only use the PicoScope's built in function generator. To do this, I made a plugin design, where a separate DLL provides the functions to interface with the signal generator.

One thing stopping me before was that I didn't have a signal generator. I found pretty quickly that the frequency range I needed would be pretty pricey. So I built my own based on a Linduino and the Mini-Kits EME165-R2. So, for now the only plugin I've developed is for this homebrewed signal generator.

Obviously this feature is only as useful as there is support for various signal generators. And I've tried to make the plugin interface as general/broad as I can imagine, but without building more plugins I don't know for sure it will handle a wide variety of instruments.
Last edited by hexamer on Tue Mar 31, 2020 9:24 pm, edited 2 times in total.

hexamer
Advanced User
Advanced User
Posts: 0
Joined: Tue Aug 12, 2014 10:09 pm

Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

External Signal Generator Part 2:

I did some initial investigation into what would be required to support the Siglent SDG2000X series and it quickly made me appreciate how much more simple the PicoScope SDK is :). I don't necessarily want to deal with NI VISA. I started to look into USBTMC and while it seems lighter weight, it would still require significant work/research. And a likely bigger problem is that I don't have ready access to a Siglent device to test.

So, that said, I'd like to see if anyone else is motivated to help out. Even if you don't have time or skills to create a new plugin, perhaps you could offer experience, suggestions, or a review of the plugin interface.

Depending on interest I'd probably start a new thread.

_Wim_
Advanced
Posts: 0
Joined: Sun Nov 12, 2017 11:31 am

Re: Frequency Response Analyzer with Bode Plots

Post by _Wim_ »

hexamer wrote:
Tue Mar 31, 2020 4:22 am
So, that said, I'd like to see if anyone else is motivated to help out. Even if you don't have time or skills to create a new plugin, perhaps you could offer experience, suggestions, or a review of the plugin interface.

Depending on interest I'd probably start a new thread.
I have some experience in controlling instruments via GPIB/VISA, and also have a Rigol DG1062Z (60Mhz). No Siglent however, but would guess that once we have a plugin that uses GPIB/VISA communication, extending it to other generators would be quite straightforward.
No promises however on time schedule, and as with my previous endeavour of the LCR meter, it could come to a halt also due to other priorities.
Programming would be done in C# and Visual Studio.

hexamer
Advanced User
Advanced User
Posts: 0
Joined: Tue Aug 12, 2014 10:09 pm

Re: Frequency Response Analyzer with Bode Plots

Post by hexamer »

_Wim_ wrote:
Thu Apr 02, 2020 7:04 am
I have some experience in controlling instruments via GPIB/VISA, and also have a Rigol DG1062Z (60Mhz). No Siglent however, but would guess that once we have a plugin that uses GPIB/VISA communication, extending it to other generators would be quite straightforward.
No promises however on time schedule, and as with my previous endeavour of the LCR meter, it could come to a halt also due to other priorities.
Programming would be done in C# and Visual Studio.
Thanks, Wim, I definitely understand getting other priorities!

Your mention of C# made me realize one thing I should mention. The external signal generator plugin interface is designed as a pure virtual C++ class. I did this to implement a factory pattern like the way I handle scopes. While I'd guess this doesn't completely prohibit other languages, I'm sure it probably makes it tougher.

Since my EME165-R2's Arduino code uses CmdMessenger and there is a PC-side C# library, my initial efforts at a plugin were calling C# from C++ using UnmanagedExports Nuget package. But that was before I made the C++ class interface and then decided that interfacing to CmdMessenger was simple enough with just straight C++.

Also, there's a Python library for USBTMC, so I might look into making a Python based DLL for the Siglent devices. This could turn out to be some interesting learnings in cross language integration!

Post Reply