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Frequency Response Analyzer with Bode Plots

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Re: Frequency Response Analyzer with Bode Plots

Postby nano » Sat Dec 03, 2016 9:40 pm

Jepp, Picolog was installed. I really appreciate your efforts and support.
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Re: Frequency Response Analyzer with Bode Plots

Postby pnb » Wed Jan 18, 2017 7:13 pm

What a fantastic application of picoscope!
I found it when I googled pico and frequency response. I want to check out an RIAA PreAmp I have made, that I believe is not correcting the high frequencies sufficiently.
Before I start I wanted to check if anybody else had done this, using this tool or not?
PS 2205 & probes Win10 64bit
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Re: Frequency Response Analyzer with Bode Plots

Postby hexamer » Thu Jan 19, 2017 2:35 pm

pnb wrote:What a fantastic application of picoscope!
I found it when I googled pico and frequency response. I want to check out an RIAA PreAmp I have made, that I believe is not correcting the high frequencies sufficiently.
Before I start I wanted to check if anybody else had done this, using this tool or not?


Thank you!

I do not recall anyone specifically mentioning testing an RIAA pre-amp, but if it's an audio amplifier and you're testing with PS2205, I can't think of any reason there would be a problem. I would assume like any amplifier your's would have relatively high input impedance and relatively low output impedance. So loading effects would not be a concern. Then the only other thing to worry about are signal levels and noise (e.g.quantization, RF, thermal etc). If the circuit must be driven with very small signals, then SNR could be a challenge, but you may just have to try it out to see. Also, remember the FRA tool is mainly a task automation tool. You can check for these potential measurement issues with the PicoScope software too.
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Re: Frequency Response Analyzer with Bode Plots

Postby pnb » Thu Jan 19, 2017 7:34 pm

Thanks for your reply.
I was about to test it with the 'standard' tools within pico after watching a Youtube video about it.
The PreAmp input is 47k, I am unsure about the output, it is an Op amp AC coupled.
Yes levels are a bit of a problem as 5mV is the 'normal' input level. I can set the gain low, about 60, but I think I have enough headroom to take the input up to 30-40mV. Still low though.
The other nuisance is that the best way to test would be with an Inverse RIAA input voltage frequency sweep, then the correct output would be flat, errors would be obvious. However I have failed to find an equation for that so I will have to feed with fixed mVs and compare the output to the RIAA curve.
Plenty to experiment with!
PS 2205 & probes Win10 64bit
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Re: Frequency Response Analyzer with Bode Plots

Postby Toni9999 » Fri Jan 27, 2017 11:51 am

Excellent work on an amazing application.

We are have incorporated the tool into an automated testing rig which also measures PSU efficiencies at various operating points (various Vin, Vout and Load conditions).

The only way we have been able to integrate the tool is to use AutoIt which is a bit clunky. I was wondering if it would be possible to get some extra boxes in the tool so you can enter a save location. This box plus a save button which would automatically save the csv and png file in the path entering in the box (path would also include the file same so the button just needs to add the extension).

Currently the saving is causing some issues as it bring up extra windows which can lose focus if a user click or types anything.

Or if you have a better solution to calling the software from another piece of software that would be useful.

Once again thank you for the outstanding work.

Toni
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Re: Frequency Response Analyzer with Bode Plots

Postby hexamer » Sat Jan 28, 2017 3:22 pm

pnb wrote:Thanks for your reply.
I was about to test it with the 'standard' tools within pico after watching a Youtube video about it.
The PreAmp input is 47k, I am unsure about the output, it is an Op amp AC coupled.
Yes levels are a bit of a problem as 5mV is the 'normal' input level. I can set the gain low, about 60, but I think I have enough headroom to take the input up to 30-40mV. Still low though.
The other nuisance is that the best way to test would be with an Inverse RIAA input voltage frequency sweep, then the correct output would be flat, errors would be obvious. However I have failed to find an equation for that so I will have to feed with fixed mVs and compare the output to the RIAA curve.
Plenty to experiment with!


Yes, I think 30-40 mV should be plenty on that scope. Even if you could only input 5 mV, that should work.
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Re: Frequency Response Analyzer with Bode Plots

Postby hexamer » Sat Jan 28, 2017 4:34 pm

Toni9999 wrote:Excellent work on an amazing application.

We are have incorporated the tool into an automated testing rig which also measures PSU efficiencies at various operating points (various Vin, Vout and Load conditions).

The only way we have been able to integrate the tool is to use AutoIt which is a bit clunky. I was wondering if it would be possible to get some extra boxes in the tool so you can enter a save location. This box plus a save button which would automatically save the csv and png file in the path entering in the box (path would also include the file same so the button just needs to add the extension).

Currently the saving is causing some issues as it bring up extra windows which can lose focus if a user click or types anything.

Or if you have a better solution to calling the software from another piece of software that would be useful.

Once again thank you for the outstanding work.

Toni


Toni,

Thank you for your interest and kind compliments. I'm happy to hear that you were able to perform some automation with AutoIt. I'm sorry to hear about your troubles. Here are some ideas that may help:

1) Instead of "Save Plot As ...", try "Save Plot" (likewise for export data). Then use AutoIt scripting to find and copy the newly created files to the file names you want. I see that it has a FileCopy function, as well as FileFindFirstFile and FileFindNextFile which may be helpful for such an approach.

2) A little while back I started work on an API version of FRA4PicoScope. I mention it here topic14311-165.html#p90581 A preliminary version with examples can be found here: https://bitbucket.org/hexamer/fra4picos ... opeAPI.zip Depending on your desired scripting language, this may be an overall cleaner route for you. I've tested C/C++ clients as well as 32bit Excel/VBA. Other languages should work, but I've not tested them. One more note is that the API only produces the raw frequency, gain, phase data. You'd need to find another way to plot if you needed that. I should also mention that it's in the early stages, so the API is subject to change.

3) If neither of these work, I could look into something else that would work with AutoIt, but ordinarily be hidden to the user. I'd rather not clutter the UI with an alternate file save interface (at least not on the main release). If you were in a hurry and really wanted to proceed with your original idea of adding file name fields and buttons, you could always make a custom fork for your environment.

Thanks,

Aaron.
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Re: Frequency Response Analyzer with Bode Plots

Postby Richard31 » Sun Jan 29, 2017 5:50 pm

Hi Aaron,

I don't find where i can tell you thank you for your software which seems to work fine with my 2204a!

Many Thanks,

Richard
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Re: Frequency Response Analyzer with Bode Plots

Postby ralphrmartin » Tue Jan 31, 2017 10:46 pm

Can I make a small request?
I'm not quite clear what A and B refer to in the interface

Can you please write a very simple "How to.." with an example, showing how to use this tool? Even better, with a diagram?

1 Build such and such very simple circuit (e.g. a filter or something)
2 Connect ... of the Picoscope to ... of the circuit
3 Connect ... of the Picoscope to ... of the circuit
4 Press ... on the software to get the plot

Thanks!
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Re: Frequency Response Analyzer with Bode Plots

Postby hexamer » Fri Feb 03, 2017 4:10 am

Richard31 wrote:Hi Aaron,

I don't find where i can tell you thank you for your software which seems to work fine with my 2204a!

Many Thanks,

Richard


Here is fine :) Thank you for the report. I also have a 2204A that I use for testing. Very nice scope!
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Re: Frequency Response Analyzer with Bode Plots

Postby hexamer » Fri Feb 03, 2017 4:17 am

ralphrmartin wrote:Can I make a small request?
I'm not quite clear what A and B refer to in the interface

Can you please write a very simple "How to.." with an example, showing how to use this tool? Even better, with a diagram?

1 Build such and such very simple circuit (e.g. a filter or something)
2 Connect ... of the Picoscope to ... of the circuit
3 Connect ... of the Picoscope to ... of the circuit
4 Press ... on the software to get the plot

Thanks!


A How-To is definitely a good idea. Something for an RC filter would be a quick write-up that I could link off the Wiki.

To answer your more immediate question, A and B refer to the scope's designation of the channels. On a two channel scope, the only channels are A and B. Usually you would assign channel A as FRA input and channel B as FRA output (these are the defaults assigned in the application). The basic idea is to hookup the AWG to the input of the circuit being measured. Then channel A would be connected directly to the input/AWG. Then channel B is hooked up to the output of the circuit.
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Re: Frequency Response Analyzer with Bode Plots

Postby ralphrmartin » Sun Feb 05, 2017 7:20 am

Thanks, got it, and what I suspected. What was a little confusing is that my Picoscope has the AWG on a separate BNC, not the A channel.
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Re: Frequency Response Analyzer with Bode Plots

Postby domme414 » Mon Feb 13, 2017 1:44 pm

Hi Community,

I have a PicoScope 5444B Oscilloscope and I want to make a bode plot of my self builded amplifier. I connect the signal generator to the channel A and to the imput of the amplifier and channel B to the output of the amplifier. With my other oscilloscope I make a shoot of the signals and I think it looks good. In the FRA tool I dont see the right signals of the bode plot and i dont know how that comes. Following you see the log of the FRA tool, please can you help me?

Status: 5444B S/N: CT607/094 successfully initialized.
Status: Starting frequency step 1, range try 1
Status: Setting input frequency to 0.978 Hz
Status: Setting input channel range to 1 V
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 62.6 Hz takes 16.4 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 1, range try 2
Status: Setting input channel range to 500 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 62.6 Hz takes 16.4 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 1, range try 3
Status: Setting input channel range to 200 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 62.6 Hz takes 16.4 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 1, range try 4
Status: Setting input channel range to 100 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 62.6 Hz takes 16.4 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 1, range try 5
Status: Setting input channel range to 50 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 62.6 Hz takes 16.4 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 1, range try 6
Status: Setting input channel range to 20 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 62.6 Hz takes 16.4 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 1, range try 7
Status: Setting input channel range to 10 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 62.6 Hz takes 16.4 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 2, range try 1
Status: Setting input frequency to 10.012 Hz
Status: Setting input channel range to 10 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 641 Hz takes 1.6 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 3, range try 1
Status: Setting input frequency to 99.977 Hz
Status: Setting input channel range to 10 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 6.4e+03 Hz takes 0.2 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 4, range try 1
Status: Setting input frequency to 1000.008 Hz
Status: Setting input channel range to 10 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1025 samples (16 cycles) at 6.4e+04 Hz takes 0.0 sec.
Status: Transferring and processing 1025 samples
Status: Starting frequency step 5, range try 1
Status: Setting input frequency to 9999.983 Hz
Status: Setting input channel range to 10 mV
Status: Setting output channel range to 10 mV
Status: Capturing 1026 samples (16 cycles) at 6.41e+05 Hz takes 0.0 sec.
Status: Transferring and processing 1026 samples
Attachments
config_FRA.PNG
config FRA
FRA_test.png
signals of input and output of the amp
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Re: Frequency Response Analyzer with Bode Plots

Postby hexamer » Mon Feb 13, 2017 6:43 pm

domme414 wrote:Hi Community,

I have a PicoScope 5444B Oscilloscope and I want to make a bode plot of my self builded amplifier. I connect the signal generator to the channel A and to the imput of the amplifier and channel B to the output of the amplifier. With my other oscilloscope I make a shoot of the signals and I think it looks good. In the FRA tool I dont see the right signals of the bode plot and i dont know how that comes. Following you see the log of the FRA tool, please can you help me?


Is there a chance you only have the 64 bit SDK installed? There have been reports of strange behavior like this with only the 64 bit SDK installed. You need to have the 32bit SDK installed for the FRA app to work.
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Re: Frequency Response Analyzer with Bode Plots

Postby Hitesh » Mon Feb 20, 2017 12:43 pm

Hi hexamer and domme414,

We have run some tests with a PicoScope 5000 Series device and believe this to be a driver issue when retrieving data values using certain parameter ranges. This has been reported to our Development Team for further investigation.

Regards,
Hitesh

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