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Re: how to make bode plots in Labview 7.1 without using Control Toolbox

I am using Labview 10. I have connected a signal generator, a LP RC filter and an oscilloscope. I am using Labview in order to control the generator (sine with frequency sweep) and acquire the signal from the scope. I want to plot the Bode diagram without using the transfer function, from the amplitude of the sine signal and the frequency.  

 

Thank you very much.

Best Regards.

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Re: how to make bode plots in Labview 7.1 without using Control Toolbox

Hi pflo,

Are you using the CD Bode Plot VI or the SI Bode Plot VI?  For the CD plot you must use a transfer function.  Below, please find a link to an example on how to create a Bode plot without using the toolkit.  


Regards,
Kira T
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Re: how to make bode plots in Labview 7.1 without using Control Toolbox

Hello there! I was looking around the net to get some informations or suggestions on how to get the bode plot from the response of an electrical circuit (for example a LP filter) feeded by a sine-sweept signal.
The sine-sweep is generated by a function generator, therefore with an oscilloscope I acquire the response of the electrical circuit that is " sent " (with IEE488 bus) to LabView.I have solved the problem of acquiring the output of the circuit , but I don't know how i can plot Bode.

 

I wouLdn't use a pre-existing subVI..thanks for the attention and sorry for my bad english.

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Re: how to make bode plots in Labview 7.1 without using Control Toolbox

Hello Caster,

 

I am wondering in what data type you have the information on LabVIEW of the response of the electrical circuit.  Please review this information on frequency response.

 

http://www.ni.com/example/6450/en/

 

Please reply with your insight on this matter, and maybe what is your final goal on this project.

 

 

Regards,

 

David M.

National Instruments 

 

 

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Re: how to make bode plots in Labview 7.1 without using Control Toolbox

Thanks for the attention Dado.MB.
I've read the documentation suggested, but,  excepet the first paragraph (frequency response), the rest is focused on the CD Bode VI.
My final  goal is to plot the bode diagrams using the information obtained by, allow the term,  "temporal response"  of the electrical circuit  acquired by the oscilloscope.
In input, I feed the circuit with a sine-sweep signal generated by an external  function generator.
I thought I'd take the peaks , using the subVI "peak detector", and the instants of time associated  to build the magnitude bode diagram (because of the frequency vary linearly during the sweep time, by a simple equation I can obtain the desired frequency in relation to the instant time considered).

I will have a couples of values (magnitude;frequency) for each peak detected..then with these values I might be able to draw the  magnitude bode diagram.

It may be a plausible idea?

The data acquired by the oscilloscope are converted into 16bit integer.
I continue to say sorry for my bad english..