Voltage Measurement definitions

Measurement Description Cursors
Amplitude The Amplitude of a waveform is the difference between its Top and Base values. The Y cursors show the values being measured.
Average Average is the sum of the waveform samples divided by the number of samples over one or more full periods. If less than one period is displayed, Average is calculated on the full width of the display.

where V_k is the value at the k^th point being measured and N is the number of points in the measurement interval.
The X cursors show what portion of the displayed waveform is being measured.
Base The Base of a waveform is the mode (most common value) of the lower part of the waveform, or if the mode is not well defined, the base is the same as Minimum. The Y cursor shows the value being measured.
Maximum Maximum is the highest value in the waveform display. The Y cursor shows the value being measured.
Minimum Minimum is the lowest value in the waveform display. The Y cursor shows the value being measured.
Peak-Peak The Peak-to-Peak value is the difference between Maximum and Minimum values. The Y cursors show the values being measured.
RMS RMS (dc) is the root-mean-square value of the waveform over one or more full periods. If less than one period is displayed, RMS (dc) average is calculated on the full width of the display.

where V_k is the value at the k^th point being measured and N is the number of points in the measurement interval.
An alternative value RMS (ac) is calculated from

One form changes if the waveform offset changes; the other does not. How does your oscilloscope calculate an rms value?
The X cursors show what interval of the waveform is being measured.
Top The Top of a waveform is the mode (most common value) of the upper part of the waveform, or if the mode is not well defined, the top is the same as Maximum. The Y cursor shows the value being measured.

Measurement	Description	Cursors
Amplitude	The Amplitude of a waveform is the difference between its Top and Base values.	The Y cursors show the values being measured.
Average	Average is the sum of the waveform samples divided by the number of samples over one or more full periods. If less than one period is displayed, Average is calculated on the full width of the display. where V_k is the value at the k^th point being measured and N is the number of points in the measurement interval.	The X cursors show what portion of the displayed waveform is being measured.
Base	The Base of a waveform is the mode (most common value) of the lower part of the waveform, or if the mode is not well defined, the base is the same as Minimum.	The Y cursor shows the value being measured.
Maximum	Maximum is the highest value in the waveform display.	The Y cursor shows the value being measured.
Minimum	Minimum is the lowest value in the waveform display.	The Y cursor shows the value being measured.
Peak-Peak	The Peak-to-Peak value is the difference between Maximum and Minimum values.	The Y cursors show the values being measured.
RMS	RMS (dc) is the root-mean-square value of the waveform over one or more full periods. If less than one period is displayed, RMS (dc) average is calculated on the full width of the display. where V_k is the value at the k^th point being measured and N is the number of points in the measurement interval. An alternative value RMS (ac) is calculated from One form changes if the waveform offset changes; the other does not. How does your oscilloscope calculate an rms value?	The X cursors show what interval of the waveform is being measured.
Top	The Top of a waveform is the mode (most common value) of the upper part of the waveform, or if the mode is not well defined, the top is the same as Maximum.	The Y cursor shows the value being measured.

Reference

54622 Oscilloscope User Guide (pdf)

Maintained by John Loomis, last updated 4 January 2009