sample spectra of mines and clutter

mines

• russian pmd-6 box mine [wood]
• russian pmn mine [plastic]
• italian vs-mkII mine [plastic]

The strongest discriminant of the plastic mines is a large bump in the 1-2 kHz range
coupled with a weak spectrum at higher frequencies.  The box mine exhibits multiple
flexing resonances of its thin walls, which however are easily damped when the mine
is buried in hard soil.  Hard objects (rock, metal, glass) show large resonances
above 3 kHz.  The softer objects show no significant modes.

russian pmn mine -- receiver operating characteristic

• tests done in harvard physics department garden
• around 100 trials
• shows probability of detection versus probability of false alarm
• simple discriminant based on strong 1-2 kHz resonance combined with lack
  of other significant features