4.5.3.2 AC Signal With Random Noise

Task: The graph will be plotted in Data Visualizer using an AC signal with random noise and an average value of the given input signal over a full cycle is observed.
  • ADC2 computation mode: Average mode
  • Input signal: AC 1V peak-to-peak, frequency 50 Hz and offset at 1.25V + random noise 0.5V peak-to-peak
Test setup:
  • Verify the computation mode number in the Data Visualizer graph is 3
  • Verify that LED D3 is illuminated
  • Configure Signal & Noise Generator to generate an AC signal of amplitude ~1V, frequency 50 Hz, and offset at 1.25V
  • Enable random noise with 0.5V peak-to-peak
  • Verify the input signal using an oscilloscope. The expected result is as shown in Figure 4-11.
    Figure 4-11. AC Signal With Random Noise Oscilloscope Capture

The Data Visualizer graph is as shown in Figure 4-12. The red colored signal is an AC input signal (ADRES value), the green colored signal is a filtered signal (ADFLTR value).

From the graph, it can be seen that the average result of a noisy AC signal is approaching to the offset value.

Figure 4-12. 50 Hz AC Signal

It can be seen that the average value of the noisy sine signal (the green colored signal) is ~390 to 410.

Note: It can be verified by adjusting the graph's Y-axis to get a clear view of the graphed signal.
  • Click the graph and press and hold the Ctrl key, and scroll the mouse wheel

The average value of an AC signal without noise is ~400 from Figure 4-10. By comparing figures Figure 4-12 and Figure 4-10, it can be seen that an average value of a noisy AC signal is close to the average value of an AC signal without noise and using the ADC2 Average mode makes it easier to calculate the average value of a noisy AC signal.