Battlefield Electromagnetic Environment Monitoring

This paper describes battlefield electromagnetic signals environment, the content andmeaning of monitoring electromagnetic environment,the composition and working principleof monitoring systems; then researchs the technologies of frequency measurement,direction-finding and the methods of signal modulation recognition, fitting to be used tospectrum monitoring. On frequency measurement technologies, it introduces searchingfrequency window method, adjacent frequency window method, phase-comparison frequencymeasurement method, analyzes the principles of frequency measurement and the advantagesand disadvantages of frequency measurement methods, points out their application conditions.On the direction finding technologies,it introduces the methods of beam searching, adjacentamplitude comparison, the measured phase correlation interferometer, measuring the timedifference and the MUSIC spectral estimation algorithm, analyzes the principles and effectsof measurement error to the measurement factors, and finding method applicable conditions.This paper focuses on the modulation type identification. By the method of instantaneousautocorrelation, short-time Fourier transform (STFT) and Winger-Vile distribution (WVD), itanalyzes the characteristics of a typical radar signal, an effective recognition andidentification of the flowchart is given, and uses these three methods to do modulationrecognition simulation experiments for single carrier frequency signal, LFM signal,phase-coded signal and frequency diversity signal, three methods obtains recognitionaccuracy under different SNR. By analysis of transient characteristics of a typicalcommunication signals, it uses four characteristic parameters of the realization of AM, DSB,SSB, FM of five classification analog modulation signal, uses the five parameters of therealization of the2ASK,2FSK, BPSK,4ASK,4FSK, QPSK of six classification digitalmodulation signal, recognition flowchartis given, recognition accuracy obtained underdifferent signal to noise ratio. For analog and digital signals classification,it uses the code rateto achieve its classification based on wavelet transform features, simulations and analysises ofthis method for AM, FM,2ASK,2FSK, BPSK,4ASK,4FSK, QPSK signal recognitionperformance.