how to filter a signal with labview 7 basic package

[aurelia]

Hello, I have a signal which are too noisy. I would like to use a filter to reduce the noise. However, I have the .0 basic version of labview. I attached the Vi to this message. Do you know how I can filter the signals?

Thanks

Anny 

[devchander]

Hi Anny,

As you must be already aware, LabVIEW base package does not come with filters.

Herez what i Suggest, try to implement some simple algorithm for a low pass filter like moving average/Smoothing filters( adjust the size of moving average window to get good noise cancellation) using labview mathematical functions and you must be able to get fairly better data. with lesser fluctuations.

Look at these links to get an idea on how to implement it.

http://www.dataq.com/applicat/articles/an14.htm

Regards

Dev

[aurelia]

I installed the Labview 7.0 Full version. I used the filter to reduce the noise in my 4 signals. The Vi is in attachment. I would like to know if this correct and also if all 4 signals are filtered.

[aurelia]

I forgot to attach the Vi. Thank you very much.

[Andy F.]

aurelia,

Yes, the express VIs are that easy to use!  You should try to change the filter settings on the configuration page (accessed by right-clicking and selecting Properties on the Filter Express VI) and watch the results to see if the signal is getting filtered to your liking or not.

Hope this helps!

Andy F.

[devchander]

hi Anny,

As Andy has already told, express Vi's are indeed the quickest way to realise filters.

Since you now have a Full Development System, do go ahead and use all the filter functionalities that come with it.

There are a lot of examples which will help you to get started

Best regards

Dev

[aurelia]

I ran the attached Vi with and without the filter. IWhen there is a filter, I got a voltage that is 4 times lower than when there is no filter. Do you know why? Is this because I have 4 signals? Thanks

[Andy F.]

aurelia,

I might recommend taking a look at the filter examples that Dev referenced (Help >> Find Examples).  This should give you some more info about how filters work.  I would recommend changing the filter cut off frequency and observing the changes in the preview window when configuring the properties of the Fileter Express VI and see if it is giving you the filter response that you want. 

Andy F.

[nazreen]

hi dev,

You said that i can apply moving average algorithm in order to filter the signal...can you give me the example on how to write a code in labview 8 base package with the moving average algorithm?

[devchander]

This VI will demonstrate Moving average alorithm.

This i had downloaded from forums in the past. ( must be Bektho's creation)

Hope this helps

Regards

Dev