Noise frequencies elimination

[shjukheter]

Hi,

         I have taken samples for 3Seconds for both noisy and noiseless 10 pumps and I plotted the data in matlab, because I don't know in labview. Anyway, I have to work with labview later. Now, I had written code in labview that writes some data to pump when if noise is in pump. I have attached my image that from Matlab. I need to exactly want to eliminate the noise in red color images. I have used highpass filter and low pass filter to see the difference in strength in matlab. As in the images until 550Hz, pump original frequencies are mixed with noise(in red color pictures) and after that it really most from noise frequencies. Can someone suggest me to find a way in labview that can differentiate this noise from original frequency.

[jyang72211]

If I understand you correctly, the original signal and the noise signal share the same spectrum.  However, for frequency greater than 550Hz, the original sigmal is very small and the noise dominate.  Thus, you want to do a high pass from 0 to 550Hz on the original + noise signal.  Is that right? 

If so, you can use one of the filter under sigmal processing -> filters for a high-pass operation.  The filtering functions maybe in a toolkit though.  However, you can always design a DSP filter from scratch in LabVIEW :).  

[shjukheter]

Based on the Noise level in the signal, I would write a value to my device and I will read the data again to check the noise levels(here I confused to use time domain or freq domain signal in labview).

In the precious image, especially the four freq domain signal images are divided from one image(noisy red-->after high pass filter with 550 as Fc, good blue--> after high pass filter with 550 as Fc, Noisy red-->low pass filter Fc 550, good blue-->low pass filter Fc as 550)

My basic doubts are

-----------------------------

1) How can I read the power of a signal(in time domain not power spectrum)  in labview i.e. I want to calculate power of signal after highpass in both cases(noisy, good). So, Based on the power value I would probably write a value to my device until gets low as blue signal value.

2) Any one can come to conclusion that the red spectrum having more harmonics compared to blue one. But, Is there any way to finf these harmonic frequencies, because these frequencies are same in my all devices.

3) Still, a bit noise is present 0 to 550Hz but my device working frequencies are also present in that region with small harmonics in red pic(blue pic indicates without harmonics only original frequencies). I hope that will be negotiable with good one(blue one). If want to really make an efficient system, I should want to remove these harmonics also(between 0 to 550Hz). How can I do this? Because I want remember that always my original frequencies are lies in that region.

[jyang72211]

Do you have the signal processing toolkit?  

http://sine.ni.com/nips/cds/view/p/lang/en/nid/209055

[shjukheter]

No, I don't have that and I install now. I am using NI-USB 6008 for data acquisition.

[shjukheter]

Hello, I have a time domain signal that I would like to filter(highpass) it out with 550Hz as cutoff frequency and then I want to calculate the power of signal after highpass filter. I have done it in Matlab by using formula here http://gaussianwaves.blogspot.com/2010/01/calculating-power-content-of-signal-in.html, I would like to do it in labview the same thing. Is there is any VI that can calculate  the power of a signal?

[jyang72211]

Under Spectrum Analysis, you have the Pwr Specturm function that you can use the calculate power.

[shjukheter]

That's not power(in watt), that will give an array of power spectrum. I just want to calculate the power(scalar) of a signal that as I shown in the above link(formula).

[shjukheter]

Hello,

             I am wondering whether I can calculate the power of a signal that coming out of highpass filter. I have done the same thing in matlab and I would like to do it in labview. In matlab, I just used the formula that I given a link above. Please help me that is there any option in labview that can calculate the power of a signal or I may go for formula in labview.

[shjukheter]

Since No one replied to my question. May be here I have clear picture that I want calculate the power(not power spectrum) of coming signal after high pass filter. I did not find any VI that can calculate the power of signal. I calculated it in matlab by using formula in above link. I hope labVIEW can also have that kind option. Please let me know that.