Research On Matched Filtering Technology In Shallow Surface Electromagnetic Detection

With the continuous development of urban construction in recent years,the construction process of underground pipeline networks has accelerated,and people's demand for proven underground information has become increasingly prominent,especially for metal objects that are shallowly buried under the ground.Its location information has important use value.There are many technologies in the field of shallow surface detection.This paper uses frequency domain electromagnetic detection technology to detect underground metal objects.Aiming at the current high requirements for detection efficiency and recognition accuracy in the field of shallow surface detection,a shallow surface electromagnetic detection system in the frequency domain has been developed.The research contents of this article are as follows:1.Investigate the basic principles of shallow surface electromagnetic detection in the frequency domain.Based on the basic principles,theoretically analyze the influence of metals on electromagnetic wave transmission,and establish a system architecture of transmission and reception.2.Doing research on the matching filtering algorithm and analyzing its unique advantages in digital filtering,especially the adaptability of matching filtering to signal amplitude,which makes it extremely convenient in the field of known signal filtering.The filtering function is modeled according to the characteristics of the target signal,and the algorithm is optimized and implemented according to the needs of the electromagnetic detection system in the shallow surface frequency domain.3.The prototype structure of the shallow surface electromagnetic detection system is designed.FPGA and DSP are used to complete data acquisition,transmission and preliminary processing.The industrial computer communicateswith the host computer software in real time,and the host computer completes the identification and positioning of the target.The FPGA is used to control the synchronous transmission and reception of the detection antenna and upload the collected data to the DSP at high speed.The DSP completes the extraction of the characteristic value components and uploads the characteristic values to the host computer.The host computer reads the advance distance of the detection antenna at first,then records the distance and the characteristic value synchronously according to time,then performs the matching filtering of the characteristic value signal,and finally realizes real-time alarm and reporting of the coordinates of the metal target.4.Completing the simulation verification of the matching filter effect,and testing the electromagnetic detection system in the shallow surface frequency domain in the laboratory environment and the field environment to verify the detection effect of the detection system on the metal target and the suppression effect of the matching filter on the noise.