Mordax DATA - Aliasing - Sampling Distortion

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MORDAX : DATA
User Guide
SYS V. 01.00.00
BOOT V. 01.00.00
Updated: 161229
In any digital sampling system, such as a digital oscilloscope, aliasing
distortion of the sampled signal can occur. In the image right there are two
sine waves signals shown in yellow, each with the same number of X-axis
divisions. In this graphic the X-axis divisions are sample points; both
sine waves are being sampled at the same rate, though they are different
frequencies. The circles show where the incoming sinewave signal is
sampled; if you draw a line connecting the points of the top sine wave
they would meet up and trace the actual sine wave input signal. However
on the bottom, higher frequency signal, connecting the sample points
draws a sine wave but doesn’t match the input signal. The distorted
signal produced is an example of aliasing distortion; the incoming signal
is too fast to be properly sampled at the current sample rate.
Below is an example of this aliasing distortion on the DATA’s scope display. The saw wave signal’s frequency is a little less than
350Hz (F4 note); with TIME: 1MS the signal is displayed appropriately, but as the TIME value is increased, there is more time
between samples and similarly each pixel on the screen spans more time. At TIME 2MS and 5MS the signal is still reasonably
displayed, while the bottom three images show TIME 20MS, 100MS, and 500MS, neither of which are appropriate for displaying
this frequency of signal. As the time per division is increased to larger and larger values, this relatively high frequency signal
experiences aliasing distortion resulting in interesting, but incorrect representations.
To avoid aliasing distortion, rst start with a smaller TIME value and increase it until the signal is displayed to your liking,
rather than starting with a large TIME value and decreasing it.
Image source: www.eldingdsp.com/alias
Aliasing - Sampling Distortion