High-Resolution Imaging Using Synthetic Bandwidth and Small Array

For sonar imaging platforms with limited space, small-size arrays pose a challenge to high-resolution imaging application. To address this problem, by using bandwidth synthesis, a high-resolution imaging method is proposed specially for small-aperture array in this paper. As wideband signals, especially ultra-wideband (UWB) signals are potentially capable of high-resolution with few elements, the proposed method is based on large-bandwidth signals. First, to overcome the limitation on instantaneous system bandwidth, large-bandwidth signals are obtained from a set of stepped-frequency chirp pluses with small-bandwidth. Second, paired-element-based imaging approach is proposed by using synthesized large-bandwidth signals. All pairs of array element signals are dechirped for pulse compression, and then delayed and summed for high-resolution image formation. Numerical simulations are carried out to test the performance of the proposed method. Simulation results show that the proposed method is capable of high-resolution image formation with small-aperture array.