Study On The Noise Suppression And Imaging Technique Of The Step Continuous Wave Ground Penetrating Radar

In this paper,the object of study is step frequency continuous wave ground-penetrating radar system(SFCW-GPR),which mainly analyzes and studies the noise suppression and imaging algorithms that are relatively hot in the field of ground-penetrating radar technology.In order to improve the performance of SFCW-GPR system in various fields,this paper will explore a complete denoising algorithm and an imaging algorithm of GPR suitable for stepping frequency system.This paper starts with the development status of SFCW-GPR system,noise suppression technology and imaging algorithm,gives a simple description of it,and then introduces the basic theory and working principle of GPR.In the research of denoising technology,this paper deals with denoising from two aspects.Firstly,echo domain de-noising is carried out.In this paper,echo domain de-noising method is adopted as the first step to process the collected echo data.The weighted average method is used to calculate the cancellation data from the pre-acquired data,and then the subtraction operation is carried out to complete the cancellation processing of the current frame data.Then,in the de-noising part of echo domain,the pulse compression algorithm based on matched filter is proposed to be applied to SFCW-GPR system.Through pulse compression processing,the coupling noise and environmental noise in the data after de-noising are further suppressed and the signal-to-noise ratio is improved.In the image domain,a histogram equalization algorithm suitable for stepping frequency continuous wave radar is proposed,and a high-pass filter before denoising in the image domain is designed for filtering processing.In the study of imaging algorithms,the common imaging algorithms of GPR system at the present stage are analyzed,and two of them are compared and analyzed,and then an optimal imaging algorithm suitable for SFCW-GPR system is proposed,and relevant simulation experiments are carried out.It is verified that compared with the common b-p and w-k algorithms,the optimized b-p algorithm balances the imaging quality and speed,and improves the imaging rate on the premise of ensuring the imaging quality.And realistic resources according to the requirements of project preparatory index,this paper builds a model experiment SFCW GPR system,the system selects the AD9959 direct digital frequency synthesizer(DDS)and HMC830 phase-locked loop(PLL)as the main hardware,STM32F103 ZET as controller,laboratory design on collocation of UWB bow-tie antenna,formed the source part of SFCW GPR system,match with modem and ARM board,using oscilloscope and spectrum analyzer to observe the testing system of electromagnetic wave signal.Based on the experiment system,the algorithm of denoising in echo domain and image domain is simulated and analyzed.The SFCW-GPR system built was used to verify the effectiveness of the echo domain plus image domain comprehensive denoising algorithm proposed in this paper by comparing images of simulation imaging results with the geological characteristics within a range of 2 meters under the shallow surface in the laboratory room.Through the research of denoising algorithm and optimization of b-p algorithm,the SNR of echo data obtained by SFCW-GPR system is greatly improved,and the coupling noise and environmental noise of the system are effectively suppressed.It is suitable for the imaging algorithm research of SFCW-GPR system,which improves the imaging rate of the system and guarantees the imaging quality.Then the performance of the whole system is improved.