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USB 6009 Data Acquisition noise

 

 

When I acquire the voltage from USB 6009, It gives some fluctuation/Noise (Please check the image, green color).

What is the reason for that?. How to overcome this noise? One way is averaging, is there any other ways to do or overcome this problem

 

Could you please suggest me?

 

 

Thank you,

 

 

 

Best Regards,

Rathan

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Hi Rathan

 

Could it be that the signal you are measuring is noisy? In that case you could filter the signal to get rid of unwanted interferance (like 50-60Hz signals from the power cables for example).

Another question is which Terminal Configuration (NRSE, RSE, Differential) you have setup your measurment to use and if your external connection matches that?

 

Best Regards

 

David

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Dear David,

 

My Terminal Configuration is  RSE. Say for Example if I connect power supply one end to Analog input 0 (AI0), other end (ground) is connected to one of the ground terminal of USB6009. Is that Ok?

 

And you have mentioned about filtering the signal? Is it same as lowpass filtering?

Do you have any guides for that? I would like to have some sample guide for it. Could you please help me to do the filtering?

 

Thanks,

Rathan

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Dear Rathan

 

The correct Terminal configuration depends on if your power supply is floating or grounded. Please have a look at tabel below.

 

 

As to the filter, which type of filter to use depends on the frequency of your signal. If your frequency (or frequencies) is low a lowpass with a cutoff frequency a bit over your frequency would be best. Conversly if your frequency is high a highpass with a lower cutoff frequency would do the job. If you are interested in only a single or small spann of frequencies a bandpass could be used.

You can filter your signal either via a hardware filter before you acquire it via your DAQ, but that would require that you have or can build a hardware filter that fits your needs. Else you can filter the signal in software after you've aquired it. The filters in LabVIEW can be found in the functions palette under Signal Processing -> Filters. I think a butterworth filter would do nicely. You can find an example through the LV Help.

 

Best Regards

 

David

Message Edited by DavidEk on 07-29-2009 05:03 AM
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