how do i know the RMS is from which peak? average? taken from what time?

[zoora]

hello, 

i think its basic but i cant seem to find the answer, im confused, please anyone who can help.

I am taking reading of voltage from a running test to obtained its current value ..basically (DAQ > to resistance ( V/R to get I) > amplitude and level measurement > RMS value

..since its a continuos data , how do i know the RMS value obtained is from which peak? or is it an average, ill give u an exmple of a paused reading to be exact...in the picture, the RMS is from which peak exactly ..how to know? is it from the overall 1s of time? or is it based on my frequency rate (i used 1kHz = 0.001s) or it is based on my input voltage frequency (50HZ =0.02s)

[GerdW · Accepted solution]

Hi zoora,

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@zoora wrote:

how do i know the RMS value obtained is from which peak? or is it an average, ill give u an exmple of a paused reading to be exact...in the picture, the RMS is from which peak exactly ..how to know?

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The RMS is calculated from all the samples that you feed into the calculation. Point.

Recommendation: Things become much clearer once you stay away from ExpressVIs and their DDT wires…

[rolfk · Accepted solution]

RMS stands for “root mean square”. The mean in there means that a certain measurement interval is averaged not just some arbitrary part of it. And the block based RMS considers the entire block as measurement interval. 

So there is no specific peak that is used but the entire block that you pass in including parts where you have no signal or a different signal. If you don’t like that, you have to examine the waveform and cut out the parts where you do not want the RMS to be calculated over. But watch out, by doing this kind of cutting in the signal you introduce other potential artifacts into the waveform that can cause transient effects into your measurement results.

[zoora]

thank you, i think i got the idea now...

[zoora]

noted, thank you