96
Table 8 - FFT waveform in split mode
6.5
Differentiation
The differentiation operation (d/dt) calculates the discrete time derivative of the source
waveform:
di = approximation to the derivative at the i
th
point
y = data point from the source channel
i = data point index
Δt = point-to-point time difference
The dx softkey under d/dt math function operation menu shows the point-to-point time
difference, and it is adjustable from 0.02 divisions to 0.40 divisions. Since the oscilloscope has 50
pixels per division, the number of samples in Δt is 50*dx. Higher values of dx reduce the noise
that is an artifact of numerical differentiation but will reduce the calculated slope at
discontinuities. Conversely, lower values of dx increase the noise but represent slopes at
discontinuities better. If the signal is periodic, averaging the waveform may help reduce noise.
