8. Glossary

noise  ;

A signal whose auto-correlation only shows a non-negligible value at zero delay. In the presence of echoes delayed in time, for example by an elastic-wave delay line, multiple correlation peaks are representative of these delays. Passive RADAR using non-cooperative sources exploits the noise-like statistics of these signals to probe the response of cooperative elastic-wave targets.

cooperative target  ;

Devices whose spectral (operating frequency range) and temporal (echo delay) transfer functions are designed to match the spectral and temporal properties of the RADAR used to interrogate them.

quality factor  ;

A resonator's ability to store energy – here in the form of elastic waves...