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3. SUM OF 2 SINUSOIDAL SIGNALS HAVING FREQUENCIES OF
10 KHZ AND 80 KHZ
3.1. DISPLAY OF THE SUM OF 10 KHZ AND 80 KHZ SINE WAVES
The low frequency (~10 kHz) indicated by the hardware frequency counter is displayed at bottom left of the screen (take care to set the triggering
level close to zero).
We use the cursors to measure the high frequency (~76.92 kHz).
When a “low-pass” digital filter having a cut-off frequency of 37.5 kHz is applied, the 10 kHz sine wave passes but the 80 kHz sine wave is highly
attenuated.
We are now going to observe the effect to the “Low-Pass” filter on the 10 kHz/80 kHz sine wave using the FFT.
Display of the Signal and its FFT with the
“Off”
digital filter.
The FFT shows the 10 kHz fundamental and the 80 kHz harmonic of the signal.