8. Glossary

noise; bruit

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.

cible coopérative; 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 confined in a cavity between two Bragg mirrors – and to...