Properties of Time-varying Linear Systems

A time-frequency duality is used to lead to a more complete characterization of time-varying linear systems. Several system functions are defined, which may be used to relate the input and output signals in different ways. In particular, a new transfer function is introduced that is dual to Zadeh's H transfer function for time-varying systems. The use of this transfer function leads to a new class of separable models for synthesizing time-varying systems. It is shown that under appropriate conditions either transfer function is determined uniquely from its real part. A new synthesis procedure based on the real-part sufficiency of the transfer function is described. (Author).