Long description
This figure is a screenshot from Signal Wizard. It shows two graphs, one labelled Time Waveform and one labelled Frequency Spectrum. The time waveform fluctuates randomly around a value of 0. Most of the time it stays within the range minus 0.25 to plus 0.25, only occasionally going outside this. The overall shape of the frequency spectrum is a diagonal line that descends steadily from minus 40 at a frequency of 0 to minus 100 at a frequency of just below 20 thousand, but again it fluctuates randomly by a small amount around this line.