Research On The False Alarm Suppression Algorithm In Circular SAR Moving Target Detection Based On Trajectory Features

Circular synthetic aperture radar(CSAR)is a new imaging mode with the advantages of multi-azimuth and long-time observation,which can realize the moving target detection of single channel system based on image sequence.Because CSAR is sensitive to 3D structure,the signature of static high target ha s rotation motion on CSAR subaperture image sequence.Such motion can cause false alarm when using image sequence based moving target detection method,like Logarithm Background Subtraction(LBS).By analyzing the trajectory difference of static high target and moving target in image sequence,a false alarm suppression algorithm is proposed based on two trajectory features,i.e.rotation angle and moving distance.The method first apply LBS algorithm to obtain coarse binary detection results,which contain moving target and static high target.After applying morphological filter to remove the noise,the DBSCAN and target tracking steps are used to extract the trajectory features of target and false alarm.Finally,the false alarm is suppressed by trajectory based feature discriminator,and output final results.The effectiveness of proposed method is verified by the W band CSAR open dataset.The main research content and innovative results are as follows:(1)The principle of logarithmic background difference method is introduced.False alarm is found in moving target detection based on logarithmic background difference method,and the source of false alarm is analyzed.Through the analysis of the moving target and false alarm motion characteristics in the experimental results of the logarithmic background difference algorithm,it is found that the source of the false alarm is the defocus signal generated by the high object in the image sequence.It provides a basis for subsequent false alarm suppression research.(2)According to the existing geometric model of CSAR,the defocusing trajectory of false alarm for static high target is analyzed,and the defocusing radius formula of static high target s is derived.On this basis,the motion trajectories of false alarm and moving target are analyzed respectively,and the differences between them are compared.It is found that there are obvious differences between their trajectories,which can be distinguished by the differences of trajectory characteristics between moving target and false alarm.The trajectory identification features are extracted for the static high target and the moving target,and the moving target and the false alarm are distinguished by the trajectory identification features,which provides a key basis for the subsequent false alarm suppression algorithm.(3)Aiming at the problem of false alarm caused by static high target in single-channel CSAR moving target detection,this paper proposes a false alarm suppression method for CSAR moving target detection based on image sequence.This method is a false alarm suppression method based on trajectory features.It distinguishes the moving target and the static high target by extracting the trajectory identification features of the moving target and the static high target to achieve the purpose of suppressing false alarm.The method steps are as follows.Firstly,the LBS algorithm is applied to the circular SAR image sequence to obtain the primary detection results(including moving target,false alarm and residual clutter).Secondly,the image sequence of detection results is processed by morphological method to remove the residual clutter in the image.Then,the DBSCAN clustering algorithm and target tracking are used to complete the trajectory feature extraction of moving target and detection false alarm.Finally,the trajectory feature identification is used to suppress the false alarm of the static high target,and the final moving target detection result is output.(4)By using the false alarm suppression method CSAR moving target detection based on image sequence proposed in this paper,the trajectory feature extraction of moving target and static high target is carried out in the W-band open source data set,the moving target and false alarm are distinguished and the false alarm is suppressed,which verifies the false-alarm suppression effect of the proposed method.