Maneuvering Target Detection In OTHR

If the target has a radial acceleration, conventional 2D-FFT based data processing method will lead to a Doppler Spread in Doppler domain. The high resolution of Doppler domain due to coherent integration no longer holds, which is very important in target detection of OTHR. Due to energy spread of return target signals between Doppler cells, both false alarms and missed alarms increased. In this paper a maneuver target detection method based on acceleration compensation is proposed to solve the problem mentioned above. With the ability to refocus return target signal energy to a single Doppler cell, This method can gain a better maneuver target detection ability.First the definition of maneuver target and a maneuver target model that is suited for OTHR is given, Then the characteristics of return signal of maneuver target is analyzed, after that, the formula used for acceleration compensation in OTHR is derived. It reveals that, for a target with constant acceleration, the return signal in Doppler domain, which is obtained by range FFT of intermediate frequency return signal of OTHR, can be approximated as a LFM signal, whose FM rate is related to acceleration.Based on above analysis, a acceleration estimation method based on Radon Wigner Transform(RWT) is proposed. The analysis of RWT shows that the resolution of acceleration estimation is reverse proportional to acceleration. The larger the acceleration, the smaller the resolution is. In order to maintain a better resolution of acceleration estimation and meanwhile reduce the amount of computation, an iterated acceleration estimation method is proposed. Based on the proposed acceleration estimation method, a maneuver target detection method is formed, which is suited for detecting single maneuver target,multiple maneuver targets as well as targets with constant velocity. The effects of sea echo to this method is also analyzed. Compare of computation complexity between this method and 2D-FFT is done. After which, a maneuver detection module based on third order accumulant is added to the method in order to reduce computation further more.At last the detection performance analysis of this method is performed and the...