194
Using the Oscilloscope
The Scope Auto Measure Menu
Preshoot and Overshoot . Preshoot and Overshoot measure the
perturbation on a waveform above or below the top and base voltages
(see the "Top and Base Voltages" section earlier in this chapter). These
measurements use all data displayed on the screen; therefore, it is very
important that only the data of interest be displayed. If you want to
measure preshoot and overshoot on one edge of a waveform, then only
display that edge. If you want to measure the maximum preshoot and
overshoot on a waveform, then display several cycles of the waveform.
Preshoot is a perturbation before a rising or a falling edge and is
measured as a percentage of the top-base voltage.
Overshoot is a perturbation after a rising or a falling edge and it is
measured as a percentage of the top-base voltage.
If the measured edge is rising, then
Preshoot =
and,
Overshoot=
If the measured edge is falling, then
Preshoot=
and,
Overshoot=
Vbase Vminimum
–()
Vtop Vbase
–()
----------------------------------------------- 100×
Vmaximum Vtop
–()
Vtop Vbase
–()
----------------------------------------------100×
Vmaximum Vtop
–()
Vtop Vbase
–()
----------------------------------------------100×
Vbase Vminimum
–()
Vtop Vbase
–()
----------------------------------------------- 100×