Agilent Technologies 54621A, User Manual, Page: 190 / 276

5- 20
Making Measurements
Subtract
Subtract
When you select 1 – 2 , channel 2 voltage values are subtracted from channel 1
voltage values point by point, and the result is displayed.
You can use 1 – 2 to make a differential measurement or to compare two
waveforms. You may need to use a true differential probe if your waveforms
have DC offsets larger than the dynamic range of the oscilloscope's input
channel.
To perform the addition of channel 1 and channel 2, select
Invert
in the Channel
2 menu and perform the 1 – 2 math function.
• Press the Math key, press the 1 – 2 softkey, then press the Settings softkey
if you want to change the scaling or offset for the subtract function.
Scale allows you to set your own vertical scale factors for subtract, expressed
as V/div (Volts/division) or A/div (Amps/division). Units are set in the channel
Probe menu. Press the Scale softkey, then turn the Entry knob to rescale 1 – 2.
Offset
allows you to set your own offset for the 1 – 2 math function. The offset
value is in Volts or Amps and is represented by the center graticule of the display.
Press the
Offset softkey, then turn the Entry knob to change the offset for 1 – 2.
A scale unit of
U
(undefined) will be displayed for scale and offset if channel 1
and channel 2 are set to dissimilar units in the channel
Probe Units
softkey.
The figure below shows an example of subtract.
Subtract
Channel 1
Channel 2
1 – 2 waveform
1 – 2
Scale
Return to
previous menu
1 – 2
Offset