Marine Panoramic Electromagnetic Environment Analysis Technology Based On Coprime Spectrum

Coprime spectrum analysis is an emerging method of spectral analysis of signals using sparse samples under under-sampling in recent years.This method can overcome the limitation of the sampling theorem and realize the spectrum estimation of the signal at a sampling rate lower than the Nyquist rate.For the spectrum sensing of wideband signals in the panoramic electromagnetic environment,the coprime spectrum analysis can realize the panoramic spectrum estimation covering the short wave,ultrashort wave and microwave,which provides the basis for communication quality evaluation and channel optimization.But there are still three main problems in the original coprime spectrum theory,which makes the performance of the algorithm unable to meet the requirements of marine panoramic spectrum analysis:(1)There are spurious peaks caused by the structural problem of the coprime spectrum analysis;(2)The resolution of the coprime spectrum is still insufficient for ultra-wideband spectral estimation;(3)The structure of the coprime spectrum algorithm is not flexible enough to realize the signal spectrum sensing of complex situations.Contraposing these deficiencies,this thesis proposes the following two improvement schemes,The first scheme is based on the parallel point-pass filtering of the coprime spectrum analysis method,which uses the grouping design of the prototype filters to eliminate the overlapping boundary frequency bands between the sub-filters,thereby fundamentally solving The problem of false peaks.At the same time,the parallel multi-path filtering process refines the filtering results,thereby improving the resolution of the coprime spectrum;The second is to propose a non-uniformly refined two-level coprime spectral structure.The results of the first-level coprime spectrum analysis are substituted into the second-level refined spectral estimation to obtain a high-resolution analysis without spurious peak effects.Based on the results,the non-uniform grouping design of the second-order coprime spectrum analysis is adopted,that is,different spectral resolutions are used for different bands,thereby improving the flexibility of the coprime spectrum analysis structure.In order to verify the validity and feasibility of the offshore panoramic electromagnetic environment analysis technology based on the coprime spectrum,this thesis studies the electromagnetic environment and signal characteristics of the maritime wireless channel,and establishes the marine panoramic wireless signal model with certain prior knowledge.The two-stage non-uniform refinement of the coprime spectrum analysis was carried out for simulation experiments.The results show that the coprime spectrum algorithm has a good effect and application prospect in the broadband spectrum sensing of the marine panoramic electromagnetic environment.