Pico Technical Support and Discussion Forum

Guest · Posted: Tue Aug 26, 2008 12:00 pm Post subject: Bode Plot with PicoScope ?

Hello,

we need to test the frequency response of a PI (PID)
loop and the system. To use PicoScopes would be nice,
so do you have an idea how to solve this problem ?

Best Regards,
Marco

picojohn · Site Admin Joined: 11 Jun 2007 Posts: 388

Hello Marco,

I am curious that you wish to measure frequency response rather than step response.

You could conceivably measure the latter with one of our oscilloscopes, however, you would need to define the parameters.

Regards
John

Guest · Posted: Fri Aug 29, 2008 3:13 pm Post subject:

Hi John,

for this application i need to measure the frequency
response, it is a very slow system in the range of 0.01 - 10Hz.
Step response is also important to see how the loop react to changes
in the system but this is easy to measure with an oscilloscope.
To design the loop it helps to see the transit frequency and phase,
therefor a bode plot is a nice tool. With a 2 channel scope and the build in
generator (awg) it should be possible to build up such a testsetup - what do you think ?

greetings,
marco

picojohn · Site Admin Joined: 11 Jun 2007 Posts: 388

Hi Marco,

What you wish to achieve is technically feasible if you were to write your own application software, and your solution would be an interesting and useful addition to this forum.

You could of course simply use cursors in PicoScope to determine time difference between channels (and therefore determine phase) at various spot frequencies, which you could then plot graphically.

Regards
John

Guest · Posted: Mon Sep 08, 2008 4:19 pm Post subject: Bode Plots

I agree, the PicoScope would be an excellent platform for Bode plots. I have put it in as a suggestion for a long time now. The manual way is just to time consuming. I have one of our software engineers looking into writing code for this. If PicoScope would do this I would be willing to work with them and spend extra for the software application just to do Bode plots. They already have some of the basic software in the spectral feature. I am also prepared to buy an upgraded scope, from the 3000 series I currently have, to a 5000 series scope.
I currently use a 2630 Tektronix Fourier Analyzer which is obsolete and we can not even get it repaired anymore. I must get something more reliable.

Guest · Posted: Wed Sep 10, 2008 6:01 pm Post subject: Re: Bode Plots

Hello,

so we are two persons who need such instrument
and i think there will be a lot more out there that
need Bode Plots for testing and development.

So it would ne nice to know if PICO TECH. will
include this option or not ?

As an option the Vellemann Scope + Function Generator
can perform a Bode Plot, but i don't like thier products,
so a solution from Pico would be better.

greetings,
marco

picojohn · Site Admin Joined: 11 Jun 2007 Posts: 388

Hi Marco & Guest,

Thank you for your inputs and, I shall pass them to our product planning team for consideration.

Regards
John

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