Agilent Technologies InfiniiVision 5000 Series Guia do Utilizador descarregar pdf (Página 161)

Making Measurements 4

5000 Series Oscilloscope User’s Guide 161

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 Zoom mode, the d/dt function does not display in the zoomed

portion of the display.

1 Press the Math key, press the d/dt softkey, then press the

Settings softkey 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

oscilloscope 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.

= y

i+4

+ 2y

i+2

– 2y

i-2

– y

i-4

8∆t

1 2 ... 156 157 158 159 160 161 162 163 164 165 166 ... 295 296

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Agilent Technologies InfiniiVision 5000 Series Guia do Utilizador Página 161