The most important thing to look for in a waterfall displays is the “strength of the waterfall. If the waterfall is too slow, it will be difficult to locate frequencies of interest. You can see this by looking at the example below (Figure 1). The frequency spectrum on top shows a display with very little noise and distortion but still records almost no waterfall energy. The bottom version shows that the same signal was recorded with twice as much noise and distortion, but the waterfall shows that it contains about four times more energy.
The other factors to consider are resolution and sensitivity. Sensitivity determines the minimum signal level that can be detected and is the basis for determining the dynamic range of a waterfall display. Resolution determines how close together or separate two frequencies can be before their respective waveforms merge into one another on a waterfall display. If you have good sensitivity but poor resolution, the waterfall will look like a roll of paper towels because the waves are smeared together. The reverse is also true: if you have a good resolution but poor sensitivity, the waterfall will look like a brick wall.