Add and subtract mode oscilloscope

[TimmyF]

what waveforms or logic signals would i want to add or subtract when using an oscilloscope?

[dscpcb]

Invert mode is used for subtracting two waveforms from the two channels connected to the oscilloscope (Channel A -Channel B).We first invert Channel B and then press the Add mode in the oscilloscope.We can use the same procedure to subtract channel B from channel A.Variable Time base is used whenever we need to fit in a low frequency signal into the screen of the analog o-scope(Remember the screen size is a constant).