Signal Conditioning

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filter 60 hz noise

Hi Everyone,

Recently i bought the following parts to measure strain from a wheatstone bridge.

1. cDAQ-9171, CompactDAQ Chassis (1 slot USB)

2. NI 9237 w/ DSUB, 4 Ch , 50 ks/s per Ch, Analog Input module

3. Ni 9923 Front-mount terminal block for 37 pin D sub Modules


For a startup , i wanted to check if i can measure DC voltage with the following modules. I called NI support and asked them if i can measure voltage with my current configuration. They said yes. So i went to NIDAQ max and chose create a task option. Then Measure Input Signals> Voltage. But i could not see any of the channel listed and it was saying device not supported. 

So i switched to another option Measure Input Signals> Strain Measurement. There my four channels were listed. Since from wheatstone bridge we would be measure voltage for the difference in strain.  So i wanted to check DC voltage through my voltage supply with this option. But when i try to do measure voltage . I could see a lot of noise especially 60 hz noise i guess.  Can anyone suggest me what i can do to filter my 60 hz noise so as to get my signal ?  Also whether what i am doing (measuring voltage from Voltage Suppy is possible with my current configuration ) ?

Any suggestions or help will be highly appreciated.


I have uploaded my graph as well as vi .  The voltage i was measuring was currently 19.8 mv.


Thank you so much.





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Message 1 of 6
use FFT to find the noise and use frequency cutoff by Butterworth Filter VI
for eliminate them
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Message 2 of 6


Thank you for your response.


Well i used the fft to check the frequency of the noise. But while doing fft i came across this problem. Well i am getting frequency response only in imaginary plot. But in real plot its just one peak. Can you tell me whether i am in the right track or wrong?


I have attached my vi herewith this , Could you please help me by checking by subvi? Thanks alot.


Also in this subvi what i am trying to do is store data in excel file.


THanks alot.



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Message 3 of 6
I am with my phone
but just see this link and tell me if it is help too you or not
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Message 4 of 6


Thanks for the useful link. I have gone through those. Could you please check my vi please when u get time?







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Message 5 of 6


Sorry it doesnt help me to get the reason that i am not getting real plot of fft. Can you please help?


Thanks .



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