How do I setup an RMS Vi to just do a RMS calculation on just a specified part of the waveform?

[JrodMillar]

I want use an RMS vi to calculate the RMS value of an incoming waveform. I only want to do this calculation on a specified part of the wave form, so it can be used to create a beam pattern for a sonar transducer. Can anybody out there help me with this problem. For instance I would like to do the RMS calculation 1.5ms to 1.7ms

[LocalDSP]

You can extract the part of interest of your waveform before calculating the RMS value. Use the Waveform tool VI called Get Waveform Subset.vi located in the Waveform Operations palette. In your case input Start = 1.5 ms, Duration = 0.2 ms and make sure the Mode parameter is set = Relative Time.