Agilent InfiniiVision 2000 X-Series Oscilloscopes User's Guide

Measurements 13The N Cycles measurement interval variation measures the value on anintegral number of periods of the displayed signal. If less than three edgesare present, the measurement shows "No edges".The X cursors show the interval of the waveform being measured.AC RMSAC RMS is the root- mean- square value of the waveform, with the DCcomponent removed. It is useful, for example, for measuring power supplynoise.The N Cycles measurement interval measures the value on an integralnumber of periods of the displayed signal. If less than three edges arepresent, the measurement shows "No edges".The X cursors show the interval of the waveform being measured.The Full Screen (Std Deviation) measurement interval variation is an RMSmeasurement across the full screen with the DC component removed. Itshows the standard deviation of the displayed voltage values.The standard deviation of a measurement is the amount that ameasurement varies from the mean value. The Mean value of ameasurement is the statistical average of the measurement.The following figure graphically shows the mean and standard deviation.Standard deviation is represented by the Greek letter sigma: . For aGaussian distribution, two sigma (± 1) from the mean, is where 68.3percent of the measurement results reside. Six sigma (± 3) from is where99.7 percent of the measurement results reside.Agilent InfiniiVision 2000 X-Series Oscilloscopes User's Guide 173