  For objects of "large" vibration size such as waves on the sea surface, the
choice of measurement method can create different understandings of system
behavior. In one case, laser vibrometry measurements of a vibrating bar in a
controlled laboratory setting, variation in probe spot size can omit or uncover
crucial structural vibration mode coupling data. In another case, a finite
element simulation of laser vibrometry measures a nonlinearly clattering armor
plate system of a ground vehicle. The simulation shows that sensing the system
dynamics simultaneously over the entire structure reveals more vibration data
than point measurements using a small diameter laser beam spot, regardless of
the variation of footprint (coverage) boundaries. Furthermore, a simulation
method described herein allows calculation of transition probabilities between
modes (change-of-state). Wideband results of both cases demonstrate the 1/$f$
trend explained within -- that the energy of discrete structural vibration
modes tends to decrease with increasing mode number (and frequency), and why.
These results quantify the use of less expensive non-imaging classification
systems for vehicle identification using the remote sensing of surface
vibrations \emph{while mitigating spectral response distortion due to coverage
variation on the order of the structural wavelength} (spectral reduction or
elimination).
