Contents I. Introduction
Transmit waveform design is critical to radar system performance. As such, waveform design has a long history and rich literature. However implied in most of the designs is the assumption that targets have infinite wideband response, i.e., point targets. Indeed many advances in radar technology have been based on this assumption. Common waveforms such as phase codes, wideband chirps, and pulse trains are traditionally designed for range resolution, Doppler resolution, and ambiguity considerations. Furthermore no provision is applied to “adaptively” change them while in operation. In fact most adaptive signal and knowledge-based processing algorithms are “receiver-centric.” Our focus here is on designing and adapting waveforms that are matched to ensembles of extended targets. When used in a “transmitter-centric” closed-loop radar system, these transmit waveforms can be adaptively modified by exploiting the knowledge learned from the environment through prior received echoes.
