Making Measurements 5
6000 Series Oscilloscope User’s Guide 211
Differentiate
d/dt (differentiate) calculates the discrete time derivative of
the selected source. You can use differentiate to measure the
instantaneous slope of a waveform. For example, the slew
rate of an operational amplifier may be measured using the
differentiate function.
Because differentiation is very sensitive to noise, it is helpful
to set acquisition mode to Averaging in the Acquire menu.
d/dt plots the derivative of the selected source using the
“average slope estimate at 4 points” formula. The equation
is:
Where
d = differential waveform
y = channel 1, 2, or function 1 + 2, 1 – 2, and 1 * 2 data
points
i = data point index
∆t = point-to-point time difference
In Delayed sweep horizontal mode, the d/ dt function does
not display in the delayed portion of the display.
1 Press the Math key, press the d/dt softkey, then press the
Source, Scale, or Offset sofkeys if you want to change the
source, scaling, or offset for the differentiate function.
• Source — selects the source for d/dt. The source can be
any analog channel, or math functions 1 + 2, 1 – 2,
and 1 * 2.
• Scale — lets you set your own vertical scale factors for
d/dt expressed in units/second/division, where units
can be V (Volts), A (Amps), or W (Watts). Units are set
in the channel Probe menu. Press the Scale softkey, then
turn the Entry knob to rescale d/dt.
d
i
= y
i+4
+ 2y
i+2
– 2y
i-2
– y
i-4
8∆t
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