A novel tandem-type adaptive line enhancer

For greatly improving the ability of the sonar detection system to detect the underwater moving target (UMT), FOCVSSBALE (fourth order cumulation variable step-size sign iteration based adaptive line enhancer) was proposed. A novel tandem-type adaptive line enhancer (NTTALE), whose first level filter is the FOCVSSBALE whereas whose second level filter is a short-term autocorrelation based adaptive line enhancer (STABALE), has been developed. The proposed NTTALE has the ability to handle undersea ambient noise twice, to enhance the UMT radiated line spectrum feature twice, and to track well time-varying signals. Theoretical analysis and simulation tests with the UMT-radiated data show that the NTTALE has the excellent performances in suppressing non-Gaussian noise, enhancing line spectrum signals, and tracking time-varying signals compared with the single STABALE or FOCVSSBALE.