Measurements 13
Agilent InfiniiVision 2000 X-Series Oscilloscopes User's Guide 179
 
The N Cycles measurement interval variation measures the value on an 
integral number of periods of the displayed signal. If less than three edges 
are present, the measurement shows "No edges".
The X cursors show the interval of the waveform being measured.
AC RMS
AC RMS is the root- mean- square value of the waveform, with the DC 
component removed. It is useful, for example, for measuring power supply 
noise.
The N Cycles measurement interval measures the value on an integral 
number of periods of the displayed signal. If less than three edges are 
present, 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 RMS 
measurement across the full screen with the DC component removed. It 
shows the standard deviation of the displayed voltage values.
The standard deviation of a measurement is the amount that a 
measurement varies from the mean value. The Mean value of a 
measurement 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: σ. For a 
Gaussian distribution, two sigma (± 1σ) from the mean, is where 68.3 
percent of the measurement results reside. Six sigma (± 3σ) from is where 
99.7 percent of the measurement results reside.