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.

Channel 1

Channel 2

1 – 2 waveform

1 – 2

1 – 2

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Offset

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Subtract

 

 

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Agilent Technologies 42A, 54621D, 24A, 54621A, 22A, 41A manual Subtract