Detection and resolution of multiple targets using time-frequency techniques

The split spectrum processing (SSP) technique, which is based on the frequency diversity principle, has been used effectively to suppress grain noise when a single target is present. However, in general, more than one target may exist over adjacent resolution cells, resulting in interference which can mask one or more of the targets and present difficulties in their detection and identification. The inter-target interference resulting from closely spaced targets exhibits strong variation with frequency. Therefore, by bandpass filtering the input signal at different center frequencies, it is possible to obtain an output signal which exhibits less interference between the adjacent targets compared to the original wideband signal. The simulation and experimental results show that by utilizing such bandpass signals, constant bandwidth SSP algorithms can yield both signal-to-noise ratio enhancement (SNRE) and resolution improvement