Research On Clutter Suppression And Wall Parameter Estimation Of UWB Through-wall Radar

Ultra-wideband through-wall radar is a new type of detection radar in recent years.The electromagnetic wave signal penetrates the wall to obtain the target scattering signal behind the wall,and finally realizes the positioning,tracking and imaging of the target.In military and civilian applications,through-wall radar detection technology is widely used due to its high penetration capability and high resolution.In practical applications,due to the complexity of the detection environment and the influence of the wall,the target signal is often submerged in various clutter,Then it affects imaging and target detection..In addition,the backward projection imaging algorithm needs to calculate the delay time using known wall parameters before imaging.But in actual detection,the wall parameters are unknown,which lead to inaccurate target positioning and deterioration of imaging quality.In addition,the detection antenna cannot keep the wall parallel measurement at any time.And directly using the target echo data received by the tilt array for imaging will cause the target to be misaligned.Based on the full understanding of the working principle of the through-wall radar,this paper has done the following research on the above problems:(1)The clutter suppression algorithm based on entropy is studied.The algorithm can not calculate the corresponding entropy value by probability formula when the amplitude of the echo received by the array has zero value,and it has the disadvantage of low signal-to-noise ratio.In this paper,a strong clutter suppression algorithm based on Laplace smooth iterative processing is proposed.Compared with the existing algorithms,the proposed algorithm can avoid the situation that the entropy cannot be calculated and the imaging quality is higher under the same number of scans.(2)Discussed the problem of inaccurate target imaging when the antenna array is tilted to the wall.The echo data used by the backward projection imaging algorithm is measured by paralleling the antenna array to the wall.However,the actual measurement of the antenna array cannot be guaranteed to be always parallel to the wall.Array tilt wall measurements can severely affect image quality and target imaging position.In this paper,a method of coordinate transformation datum correction based on wave field continuation is proposed,which can effectively solve the target imaging offset and the failure of imaging algorithm,Imaging algorithms get higher applicability.(3)A wall parameter estimation method based on image sharpness is proposed.By using the characteristics of the image features changing with the parameter transformation of the wall parameters,multiple image sharpness curves are obtained,and the curve intersection points are the estimated wall parameters.Compared with existing algorithms,this method can estimate the wall parameters more accurately.