A spectrum analyzer is connected to an unknown signal. The spectrum analyzer displays the power level of signals in dBm vertically and frequency horizontally. The spectrum of the unknown signal creates the following display:
A vertical line at at 0 Hz (DC)
A vertical line at a frequency of 20 kHz
A vertical line at a frequency of 40 kHz with less power than at 20 kHz
Additional vertical lines at 60 kHz and 80 kHz with power levels below that at 40 kHz
a. What sort of waveform does the input signal have?
b. Is the input signal periodic or non-periodic?
c. If the input waveform is periodic, what is its period?