Analysis Of SNR Of Laser Warning Receiver Based On Coherent Identification

In order to countermeasure increasingly serious threat from hostile laser in modern war, it is urgent to make research on laser warning technology and system, the ratio of signal to noise (SNR) is one of important performance parameters in laser warning receiver (LWR), which directly decides detection sensitivity and the ability of noise reduction. The analysis of SNR is quite necessary for the design and improvement of the warning system.At first, the experiments were carried out to determine the statistic characteristics of the solar noise and the noise of the charge coupled device (CCD). The results showed that the two kinds of noise both are uncorrelated Gaussian white noise by analyzing the probability density function, power spectral density and correlation function.The principles of two kinds of laser warning receivers that are typical coherent identification laser warning systems were introduced. The intensities and probabilities of the laser signal and receiver noise were analyzed. Based on threshold detection theory and Neyman-Pearson criteria, the current equation of the signal was established by introducing detection probability factor and false alarm rate factor, then, the general expression of SNR of laser warning receiver based on grating diffraction was deduced. The general expressions of SNR of the interferogram and the spectrum of the laser warning system based on Fourier transform spectral discrimination were deduced by introducing the noise equivalent power (NEP). In order to validate the method, theoretic calculations and experimental results indicate that these analysis methods are feasible, which can be used in performance analysis of LWR.Finally, wavelet threshold de-noising method was used to analyze the experimental signal of the two systems. The results showed this method can make some de-noising effect.