Averaging Measured I(t) Signal

[AT12]

Hi,

I'm trying to average my I(t) data so that I can save an averaged I(t) plot along with a PSD plot.

The issue I have is that: say my PSD is formed from 25 I(t) averages, then I get 1:25 I(t):PSD plots, which is inconvenient when I process the data + I get large data files.

Is there a way to average all the I(t) data in line with the PSD.

Attached is my VI.

I'm fine with Express VIs but a complete novice otherwise with little experience in these things, so some assistance would great!

Thanks for reading my question,

AT12.

[kurabiye]

If you have a chance to save it in a compatible format to earlier version, I believe more users can open your file. I tried to open it with 2010, couldnt make it. 

[AT12]

I've selected 2009 in Save as previous version: hopefully you'll be able to open this.

[johnsold]

Since you have made no attempt to average anything in the VI you posted, it is not clear exactly what you are trying to do.

If you want your PSD to be formed from the average 25 readings from the DAQ Assistant, then you need to do your averaging before feeding the data to Spectral Measurements.

How does the program know when 25 readings are available?

Are the successive data sets synchronized in some way? If not, everaging may tend to destroy the very signal you are trying to measure.

Lynn

[AT12]

"If you want your PSD to be formed from the average 25 readings from the DAQ Assistant, then you need to do your averaging before feeding the data to Spectral Measurements." - Spectral Measurements is averaging 25 psd plots from 25 I(t) plots, right? What I want is to have the I(t) data that feeds this PSD output to be saved as an average value along with the PSD, i.e. to save an I(t) plot made up from 25 averages.

As I said I know very little about any of this so I don't know where to start.

Your suggestion is to average the raw I(t) input and then do PSD on that? If so, could you tell me how you would go about averaging a set number of the raw input, i.e. the I(t) data? (I'm particularly bad with the loops by the way! so a little bit more detail than normal would be appreciated!)

Many thanks for replying to my question,

AT12

[johnsold]

I never use the Express VIs for spectral measurements.  It is too hard to tell what they are doing internally and I was doing spectral analysis on LV long before there were any Express VIs. 

On checking, I see that it does averaging.  The Help does not describe what the output is on the first 24 iterations.  You should probably check the "averaging done" output and only record the data when that is true.

The Help also cautions that the input data must represent one cycle of the signal: "...assume that the finite block of signal data represents one period of a periodic signal." I do not have the DAQ Assistant and cannot tell if you are acquiring one period of your signal in a synchronized manner.  If you are not, the spectrum will not accurately represent the signal you are trying to measure.

Please describe your signal or post the VI with some typical data saved as default.

Lynn

[AT12]

Sorry for the late reply but I've been away for a week.

Summary of my problem:

In my vi I have the DAQ Assistant, from this I obtain a waveform, which is excatly how I want it to look and be. All I need to do is to collect x amount of waveforms and then find the average of these waveforms, i.e. average each data point from x waveforms to find the Average Waveform. I could do it myself with a calculator but it would take too long!

I imagine I would need a for loop to collect the x waveforms before averaging - I've tried this but I'm new to LabView and can't get it to work. I need to be shown how to please.

I would really appreciate if someone could create this for loop structure in my vi.

AT12