display graph over one complete period in labview.

[rebelstar]

Hello,

How can one plot the waveform ( for example - fequency response ) over one complete period?.

I could only display it over 0 to pi.

Can i do it over 0 to 2*pi  or perhaps  -pi to + pi?

( i used the waveform chart and connected to it, the output of frequency response of the frequency analysis vi )

Many Thanks,

Kishore.

[Pablop]

Hello Kishore,

I normally use Waveform Graphs, not Charts. Essentailly, graphs generate a new plot each time they receive the data, whereas a chart appends the data.  As a default, they generally display all of the data passed to them, and adjust automatically to fit the data. However, all of the grpahs parameters are accessible through property nodes.

[rebelstar]

Hello Paul,

Thanks for the reply.  I now checked properties menu of the Waveform Graphs, where i was able to change the display scale - Minimum and maximum.

for example - If i  give scale over one period  say -pi to +pi  or 0 to 2*pi  -  i get the graph scales visible,  but the frequency response replica is not available.

But i have included complex congugate poles and zeros in my filter design. Is it a problem with the filter design ? .I am new to labview and hence the question.

Also i could not get any options under properties of filter analysis  vi.

Thanks again.

[gan_archan]

Hi,

Am new to Labview as well. 

I am facing the same problem as you have stated. First of all, am able to plot Frequency response only as a normalised frequency. And not in radian. i could give values from -0.5 to 0.5 for an entire period. I wanted it in terms of radian (-pi to pi) - is this possible?

Also, when i gave -0.5 to 0.5, the graph was drawn only for 0 to 0.5 -  i could not see a response on the negative half plane (even though the filter was designed for the negative values also) 

How did you solve the issue? 

Thanks

Arch

[Coq_Rouge]

Why not scale your X-axis with the scalefactor pi/.5

[rebelstar]

But scaling only extends the axis. What i mean is i dont get the frequency response  for pi to 2pi -but scaling can be obtained

[Coq_Rouge]

Maybe we can help you if you post a more thorough description of your problem.

[gan_archan]

Hi All,

I have designed a simple digital resonator filter having 4 poles and 4 zeroes. The peaks/poles are at pi/3, 2pi/3, -pi/3 and -2pi/3.

I gave the output of this filter into a filter analysis block. From this block's output, i am trying to plot the magnitude, phase and the poles and zeroes plotted in zplane. 

The scale of the graph drawn has been changed to show -pi to pi (X scale) 

The expected output is to show peaks at the 4 peaks mentioned above.

But what i see in the output is only 2 peaks (at pi/3 and 2pi/3 ). Am not able to get the peaks at the negative frequency. (-pi/3 and -2pi/3) -   both magnitude and phase response.

Also, the z plane graph shows only the upper half of the unit circle. the lower half of the unit circle itself does not get drawn. (Even though i have changed the scales to show negative values) 

Am not sure how to get this done. 

 I hope this is a better explanation. 

And am really hoping someone could point out  what the obvious issue is. (Am sure its not the filter design problem 🙂  ) Any thoughts?

Is there any property in the graph we should be changing other than the 'scale'?

Regards,

Arch

[kcgopal]

if we have two inputs to the waveform chart i think we can display the full period but changing the offsets for each input...

[Pablop]

Somebody needs to post some code, with data, so that we can understand what you are trying to do.