The results of the analysis are typically plotted along with a curve representing the space station combined vibratory limits to compare the acceleration environment to these prescribed limits. Spectrograms provide a road map of how acceleration signals vary with respect to both time and frequency. To produce a spectrogram, PSDs are computed for successive intervals of time. The PSDs are oriented vertically on a page such that frequency increases from bottom to top. PSDs from successive time slices are aligned horizontally across the page such that time increases from left to right.
Spectrograms are particularly useful in identifying when certain activities begin and end.