Editorial Introduction to the Special Issue on Recent Advances in Wideband Signal Processing for Classical and Quantum Synthetic Apertures

A key aphorism pertaining to the nature of instrumentation comes from (although the attribution is sometimes disputed) the Italian scientist Galileo Galilei: “ Measure what can be measured, and make measurable what cannot be measured .” Clearly, making things measurable is akin to choosing appropriate methods to measure them. From the perspective of signal processing, such techniques involve designing efficient signal acquisition systems and processing the acquired signals to extract relevant information.