Deconvolving Range Profile for Sonar Imaging Using Stepped-Frequency LFM Pulses

An imaging sonar using stepped-frequency linear frequency modulation (LFM) pulses can improve the range resolution. Nevertheless, the range resolution cannot be increased freely since the ping number is limited by the medium instability. Furthermore, the range sidelobes (SLs) are high due to the spectrum leakage between transmitting pulses. In this letter, we propose a deconvolution method to simultaneously increase the range resolution and suppress the range SLs. We use the sum of auto-correlation functions of the stepped-frequency LFM pulses to design the point spread function and use the Richardson-Lucy algorithm to deconvolve the synthesized range profile. Moreover, we consider the nonideal condition involving the amplitude and phase errors across sonar pings. Numerical simulations and real data results validate the effectiveness of the proposed method.