How to get only the dc component of a dc signal with noise?

[rmoreira]

I need to read a temperature value (a dc value). However signal has some noise in it, and i need to get it out. How can i make it? Using a low pass filter? Which one.? Is there any DC pass filter?

[Enrique]

First, depending on the sensor you are using and how you are making the measurement, make sure you use the appropriate VI from the palette:

Data Acquisition -> Signal Conditioning

Sure you can use most of the filters located in:

Signal Processing -> Filters

Create a constant from the "filter type" input and select "Lowpass".

There is also an AC & DC estimator vi, located in:

Signal Processing -> Measurement

Always remember to check the shielding of your system.

Finally, check the following at NI, which have good information on how to get rid of noise:

DC voltage

Regards;
Enrique

[Oleg]

Hi,
you may use something like "running mean" filter. To do it you need to calculate the mean value in some range arround every point. It will decrease the value of the noise and will give you the dc value (or slow changing part) of your signal.
Also you can use median filter.

The example is attached.

Good luck.

Oleg Chutko.