averaging my dc signal

[h0000]

I am wondering if I could ask some questions here about my LabView programming. Basically what I am trying to do is to measure a DC signal with unexpected noise. To eliminate the noise, I am thinking of averaging the signal. Currently I have no idea how I could do with NI LabView. Could someone give me some basic ideas?

Thanks.

[parthabe]

Try the Basic Averaged DC-RMS.vi in the Waveform pallette.

What version of LV do you use ?

[h000]

I can not find it from Waveform pallette. How can I find it? I am using LV8.0

[Dennis_Knutson]

It's not on the waveform palette. Its on the Signal Processing>Waveform Measurement palette. If you did a search for the function and did not find it, then you probably have the base version of LabVIEW. The function is only included with the full or higher versions of LabVIEW. Included with the base version is the Mean function. This requires an array of values.

[h0000]

Thanks for your reply.  Yes, I found Average DC/RMS.vi. Now my problem is how to set Keithley Multimeter as a Signals In for this VI. I am using Keitley 2700 Multimeter/Data Acquisition System.

I don't know if it is appropriate, but I attached my VI here. This is what I used before. It only takes one-shot measurement. Now I am wondering how I could revise it so as to take bunches of readings for each channel(101-104 ) and then average them.

Thanks again.

[Yi Y]

Hi h0000,
I took a look at your VI, and since I do not have the subVIs, it's hard to tell exactly how the instrument takes measurements.  You said that it takes "one shot" measurements, is it possible to use a loop to take multiple measurements, and build an array to be passed into the RMS vi?  You can control the data acquisition rate using Wait Until Next Multiple and use Insert Into Array to build an array from the data you acquire during each iteration of the loop.

Yi Y.
Applications Engineer
National Instruments
http://www.ni.com/support

[h000]

Hi, Yi Y.

I attached my subVI here. Could you please take a look at it? I think you gave me a very good idea, but I don't have a very clear picture on that. If you can put your idea on my VI, that would be great.

Thanks,

h0000

[Dennis_Knutson]

A simple loop like the one below will work. Don't understand some of your VI. The case statement and the comparison to the timer value seems totally unnecessary.

[h000]

Thanks a lot for your PNG file. I was trying to do the exactly same design on my labView, but found that I could not find some corresponding elements, such as I32(iterations), DBL(array), (error out), and U32(millisends to wait). Could you tell how I can find them from the Functions Palette? Many thanks!

[Dennis_Knutson]

They are controls and indicators. You created a control for the for loop iterations. Create the rest in the same way. You can create them on the front panel or right click on the function and select Create>Control or Create>Indicator. You'll only have a problem with the error out indicator. If you'll notice, I used a shift register for the error out. This is really basic LabVIEW skills. I would highly recomend you spend some time learning some of the beginner skills. Check the free on-line tutorials at http://www.ni.com/academic/lv_training/how_learn_lv.htm. The loop I did is also one of the basic functions in LabVIEW that you should know how to use.