Research On Energy Integration Method For Maneuvering Weak Target Detection

Radar targets in modern battlefield have the characteristics of high velocity,strong maneuverability,strong stealth ability and so on,which is a serious threat to radar early warning systems.In order to improve the ability of modern radars for maneuvering weak target detection,energy integration methods,like track-before-detect(TBD)and long time integration(LTI),are the most commonly used means,which are also hot issues in present research.The phenomena of range migration,Doppler spread and Doppler ambiguity are urgent problems for the detection methods to be solved.In behalf of improving the early warning ability and increasing the warning time,the research of several energy integration detection methods is carried out in light of the characteristics of maneuvering weak targets.The main contents of this dissertation are as follows.1.Aiming at the detection for maneuvering weak targets on the sea surface,a novel dynamic programming(DP)based TBD(DP-TBD)algorithm is proposed.The maneuverability coverage of the traditional DP-TBD algorithm is limited to the default range of the valid state transitions.When the default range is set too small,the traditional method will be invalid to the maneuvering targets;when too large,its detection performance will seriously degrade.In allusion to the above limitations,a novel DP-TBD algorithm suitable for maneuvering targets is proposed.By means of state transitions optimizing,the efficiency of the status searching for the maneuvering target is improved,and the searching range is extended.Through transfer speed weighting,the energy accumulation can be carried out according to the target motion tendency.Without altering the input parameters,the proposed method can detect targets with both strong and weak maneuverability.And the detection ability of the proposed method for maneuvering targets is much higher than that of the existing methods.The performance of the proposed algorithm and the traditional method is compared through simulation experiments.The applicability of the algorithm is verified by real measured data.2.Aiming at the detection for maneuvering targets with high velocity and radar cross section(RCS)fluctuation in the air and space,an adaptive LTI method based on DP is proposed.The proposed method strives to detect a maneuvering target with an unpredictable range migration and fluctuating echoes by jointly applying three main ideas: the improved DPprocedure that could search the maneuver position and velocity at each frame;the multipulse integration that could suppress the influence of fluctuation;and the adaptive step with fading factor that could allow the integration time to be suitable for each searching velocity.Compared with the existing methods,the proposed method can efficiently detect the maneuvering fluctuating target.Simulation results and performance comparisons show the superiority of the proposed method.3.Aiming at the detection for high-speed maneuvering targets without RCS fluctuation in the air and space,a DP based long time coherent integration detection method is proposed.At present,most of the existing methods estimate the motion parameters of the maneuvering target through complicated multi-dimensional searching,then complete the range migration correction and Doppler spread compensation on the basis of the previous estimation.In practice,the movement of the maneuvering target is very complex.It takes an extremely high estimation order to get accurate motion parameters.But when the motion parameters of the target change during the observation,however high the order is,it cannot do anything to help.Combining the DP state searching with improved multi-pulse coherent integration,the proposed method can fully integrate the energy coherently along the target track,and recursively compensate the range migration,Doppler spread and Doppler ambiguity.Simulation results and performance comparisons show the accuracy and superiority of the proposed method.4.Aiming at the early warning and monitoring mission of the space borne surveillance radar,firstly,the orbit modeling of the spatial non cooperative target is completed.Secondly,the RCS fluctuating characteristics with varying frequency,incident angle and azimuthal angle are simulated.Thirdly,the radar echoes of the spatial target are imitated by combining the two previous steps.Lastly,two energy integration detection methods are proposed according to the characteristics of the spatial target.The proposed blocked Hough transform efficiently integrates the target energy through intra-frame coherent integration and inter-frame noncoherent integration with range migration compensation,which lead to a good detection performance.The proposed coherent Hough transform,which is a coherent improvement of the fast Hough transform,compensates the Doppler shifts in accordance with different searching velocity at the moment of the Hough mapping,which has the immunization of Doppler ambiguity and a good efficiency of energy integration.