EXTERNALLY LINEAR, TIME-INVARIANT SYSTEMS AND THEIR APPLICATION TO COMPANDING SIGNAL PROCESSORS

This paper considers externally linear, time-invariant systems which c an be internally nonlinear and/or time-varying, Several examples of th e synthesis of such systems are presented, and it is argued that they offer advantages in comparison to internally linear, time-invariant sy stems, In particular, their use in signal processing is considered, an d it is shown that they can be designed to reduce the undesirable effe cts of overloading and noise corruption through the use of companding, It is shown that a variety of previously proposed schemes for this pu rpose are all related; Several practical problems are discussed, as ar e performance criteria and types of measurements needed for the evalua tion of the systems discussed.