Research On Detection Method Of Electromagnetic Geographical Environment Change Based On Frequency-Intensity Curve

Electromagnetic geographical environment is closely related to the industrial production and people's life.Since public infrastructure such as various power communication systems,domestic appliances and electronic facilities being popularized,the electromagnetic radiation sources in the geographical environment are rapidly increasing,which leads to the increasingly complex electromagnetic geographical environment.The problem of electromagnetic radiation pollution has been paid more and more attention.With characteristic of time-space-frequency,it's very important to monitor,evaluate and analyze electromagnetic geographical environment scientifically,and beyond this to master the law of electromagnetic radiation in the geographical environment.The Vehicle Electromagnetic Environment Monitoring System developed by Key Laboratory of Virtual Geographic Environment breaks through the limitation of traditional electromagnetic environment monitoring technology,and has the characteristics of full frequency and mobility detection.In this paper,the electromagnetic frequency-intensity curve is constructed based on the acquired data which collected by the Vehicle Electromagnetic Environment Monitoring System.On this basis,introducing the curve similarity measure method,the similarity of electromagnetic frequency-intensity curves can be measured.Then the abnormal changes of electromagnetic radiation in geographical environment can be discovered.The main research works was completed in the following aspects:(1)On the basis of discussing the operation mode and characteristics of the technical equipment of the Vehicle Electromagnetic Environment Monitoring System,the obtained data was analyzed,and algorithms dealing with all different types of data was designed.Then the electromagnetic environment data was organized and visual expressed using GIS technology and database technology,in order to offer the foundation of the further researches.(2)Drawing support from the concept of ground object spectrum in remote sensing,electromagnetic frequency-intensity curve was constructed using electromagnetic radiation data which obtained by mobile monitoring system.According to the different characteristics of different frequency bands,processing methods of cumulative curve and filter denoising were applied respectively.For filtering denoising method,different filtering methods are used for comparative experimental analysis,and according to the experimental results,the adaptive median filtering method was finally selected for curve denoising.(3)Introducing curve similarity to electromagnetic geographical environment change detection,several commonly used curve similarity measurement methods were analyzed.According to the characteristics of electromagnetic frequency-intensity curve,the similarity method of electromagnetic frequency-intensity curve based on discrete Frechet distance was presented.Using this method to measure the similarity of electromagnetic frequency intensity curves for spatially adjacent sampling points.This method was applied both locally and globally to detect and analyze abnormal changes in electromagnetic and geographical environment,then the spatial location and frequency range of electromagnetic radiation anomaly can be effectively identifed.(4)On the basis of the theoretical research results,the automatic detection and analysis system was designed and developed.This system can provide users with many functions,such as data management and maintenance,collected data processing,basic map operation,attribute information querying,electromagnetic change detection and so on.Summarily,the automatic detection of the spatial position and frequency range of the electromagnetic radiation intensity changes in the geographical environment can be realized.The innovation of this article is mainly reflected in two aspects:(1)Construction and analysis of electromagnetic frequency-intensity curve;(2)Similarity measurement method of electromagnetic frequency-intensity curve based on discrete Frechet distance.By analyzing the similarity of electromagnetic frequency-intensity curves for spatially adjacent sampling points,the abnormal changes of electromagnetic radiation in different space positions and different frequency bands can be discovered,which can provide the help for searching locations of electromagnetic radiation sources,and lay the foundation for the analysis and evaluation of electromagnetic geographical environment.