How to change sampled signal to previous signal with some type of resampling??

[pazuzuu]

Hello everyone!

I have a problem.
I want to show in my program working a Theory of Sampling with Nyquist condition. I know how to do sampling in my program, but i have some problem when i want to resample this signal from those sample which i get from sampling. With theory i use a lowpass Butterworth filter with high cut-off freq set as Pi/T wher T is 1/fs and fs is signal frequency. Pi of cours is Ludolfina (3,14..).

I dont know how to work it out. Resampled signal looks like i'll connect points from sampled signal with lines. I want to add some smooth to this resampled signal. Equal important for me is to show on this resampled signal aliasing when we chose to small sampling frequency.

I've hope so You understand what i mean.
I'll be realy wery glad for any help from You.

Thanks and sorry for my english.


Message Edited by pazuzuu on 01-22-2008 07:02 PM

[Juan G]

Hello Pazuzuu,

It seems like you want to demonstrate the Nyquist Sampling theory with this example. However, I am not sure what are you trying to demonstrate on the resampling and sampling portions of your VI. Can you explain a little more what you want to accomplish in the resampling and sampling graphs?

Regards,

[pazuzuu]

Hello Juan G

In sampling part of my vi i want to took some samples from earlier generated signal and show it on graph. This how many i'll get this sampels is depend with sampling frequency. I think that this part of my vi's work correctly.

In resampling part i want to recover primal signal using only data whith i get after samplig. And there i don't know how too do it. I heard that i should use a lowpass filter but i don't see any god resault. I want to show in this part, that if sampling frequency didn't match Nyquist term on our recoverd signal we will see aliasing.

I dont know how to do that this recovered signal will be so smooth as genereted.
I've hope tha You understand me. If not please ask and i try again to explain it to You:) My english sucks... sorry.
Best regards
pazuzuu

[LaurenLL]

Hi Pazuzuu,

So if I am understanding you correctly, the "sampled signal" indicator you have is showing the data you are hoping for, and it is the resampled data you have questions about.  What do you mean when you say you are trying to get the 'primal data'?  What exactly is your goal for the resampled data? 

I know that right now you are taking the sampled data and simply running it through a low-pass filter.  This should only cut off frequencies above the specified value.

Regards,

Lauren

[pazuzuu]

Hello
I want to say thank you to everyone who bring me a help.
I have solve my problem in other way. I resignate with operation on array end use only expreses.
This is what i get.

Thx.