Radar Broadband Weak Signal Detection Technology And Its Applications

As a part of the software radio based electronic surveillance system ,the task dose the research in theory and realization of detecting wideband weak radar signals. Through researching the definition, source and formation of wideband weak signals, and using the basic theory of signal detection,we presents the method of dual-receiver cross correlation processing. The paper analyses the signal processing with emphasis on Signal to Noise Ratio (SNR) in output of correlator and SNR in signal power spectral density. This method uses two spatially separated receiving equipment .Cross correlation of the two outputs will therefore yield the Auto Correlation Function (ACF) of the signal, plus noise which is spread uniformly over the whole width. The time-domain filter can then be used to select the narrow central portion of the cross correlation function (CCF), capturing virtually all of the signal but rejecting most of the noise. Taking the Fourier transform of this windowed CCF produces the time-domain filtered cross spectral density (TDFCSD). The SNR can be improved with using the character of noise which distribute uniformly in frequency domain. The cumulation of TDFCSD in a certain period eliminates the remainder noise more, and the ability of detecting signal's frequency is improved.This task combines theory with practice of software radio based electronic detection system. A computer simulation illustrates the method involved, and the results shows excellent agreement with the analysis. The research work of this task provides the basis for development of practical equipment, and has the value of definite application. Further more the adoptive technique in this task can be used in many fields which also exists the problem of weak signals' detection, as such communications, remote sensing, remote detection etc.