Frequency diversity for active sonar/radar application and optimal receiver design

MIMO (Multiple Input Multiple Output) concept has been explored for radar/sonar application recently for improving target detection and estimation performance. The existing work in this direction mainly investigates the spatial diversity and waveform designs based on the assumption of the same carrier frequency for multiple transmitters. In this work, we investigate the frequency diversity by using multiple narrowband transmitters of different center frequencies. We prove that the ambiguity function for such signal is not an optimal receiver, and propose an optimal receiver for signals with different frequency components.