Spectrum RMS Toggle

Macro: RMS

You can toggle RMS ( Root Mean Square) mode from the Spectrum dialog button, or directly via CTRL+ALT+R even when the dialog is not visible.

The RMS method is useful in engineering work because it allows comparisons of different waveforms based upon their equivalent energy. When the waveforms are all sinusoids (like the individual components of a line spectrum), then this is not so important. However, RMS is the standard method for reporting magnitudes, so you will often need this for compatibility.

Standard laboratory devices like AC voltmeters are calibrated to show RMS, so showing the Daqarta Spectrum in RMS mode makes comparisons simpler.

When linear (as opposed to Y-log power) Spectrum is active, RMS mode will cause the trace and readouts to be multiplied by 0.7071 to convert sine wave amplitude to RMS.

RMS has no effect when Y-log mode is active. That's because the dB units that it uses represent ratios of measured values divided by the full-scale range. These must be comparable values, either both magnitudes or both RMS. In other words, multiplying both the numerator and denominator of a ratio by 0.707 doesn't change the ratio.

Macro Notes:

RMS=1 sets Spectrum RMS mode, RMS=0 removes it, and RMS=x toggles between states.

See also Spectrum Control Dialog