Research On Solf Fault Detection Method Of Coaxial Cable Based On Inverse Scattering Theory

The detection and repair of cable faults can provide powerful guarantees for the continuous and high-quality supply of power and communications.In particular,the detection of soft faults in cables is of great significance in preventing system accidents and maintaining stable,safe and reliable operation of the system.At present,there are no technical difficulties in detecting and locating cable's hard faults,but the detection of cable's soft faults is still a major challenge.Therefore,in this paper,the soft fault detection of the cable is discussed.Based on the study of the transmission line model of the ideal cable,a soft fault detection method based on the inverse scattering theory is proposed,and the compensation method for attenuation is given through the analysis of the loss of the actual cable.The soft cable fault detection method based on the inverse scattering theory is applicable to the detection of actual cable soft faults.The specific work is as follows:This paper first introduces the transmission line model of the cable,and gives the calculation process of the distribution parameters of the cable with the RG58-SYV-50-3type coaxial cable as the object,and analyzes the response relation of each parameter to the frequency.The characteristic impedance of the cable is selected as the characteristic parameter of the soft fault of the cable,referring to the detection principle of the general cable fault and the result of the frequency response of the cable parameters.The soft fault model of cable is established by using CST software to explore the influence of the characteristic impedance of cable in different forms and different degrees of cable fault,so as to verify the rationality of the selection characteristic impedance as a description of the soft fault of the cable.Secondly,the problem of soft cable fault can be regarded as an inverse scattering problem.By analyzing the transmission line model of the ideal cable,the wave equation of the cable is deduced and written as the one-dimensional Schr?dinger equation,so as to achieve the mathematical modeling of the inverse scattering problem of the cable.Then,the specific solving process of the Gelfand-Levitan-Marchenko equation in the inverse scattering theory is given,and the reconstruction of the potential function in the Schr?dinger equation is completed.The characteristic impedance of the cable is reconstructed based on the relationship between the characteristic impedance and the potential function.The soft fault of the cable is judged by the analysis of the characteristic impedance after the reconstruction,and the corresponding soft reasons are designed.The obstacle simulation example is used to verify the soft fault detection method.Finally,the loss of the actual cable is studied in depth to understand the process of signal attenuation.The method of attenuation compensation for the scattering parameters of the actual cable is put forward,and the application of the soft fault detection method based on the inverse scattering theory in the soft fault detection of the actual cable is realized.The actual soft fault model of the cable was designed using RG58-SYV-50-3type coaxial cable.It was used to verify the effectiveness of the cable soft fault detection method based on the inverse scattering theory in the detection of actual cable soft faults.The limitations of the vector network analyzer used in the measurement of cable scattering parameters were explored,and it was concluded that when using a vector network analyzer to detect cables,the total attenuation cannot exceed-40 d B,and the use of cubic splines The interpolation method supplements the missing value at 0 Hz in the actual measurement.The test results show that the error detection method of the cable soft fault based on the inverse scattering theory does not exceed 5? in the actual cable soft fault detection.