Signal Extraction Technology For Underwater Detection Light Screen

The testing of the velocity of underwater firearms is a key part of their production and development process and plays a vital role in the development of underwater firearms.When using the detection light screen to measure the projectile velocity of underwater firearms,due to the special characteristics of the underwater environment,the signal-to-noise ratio of the signal that the projectile passing through the screen is low,and the effective signal is drowned in noise,so that the cross-correlation algorithm cannot be used to extract the time interval the projectile passes through the two light screens and it is difficult to obtain the velocity of the projectile To address the above problems,this thesis focuses on the extraction technology of the signal that the projectile flying through the screen,the main research content includes:(1)The characteristics of the signal that the projectile passes through the underwater detection light screen and the impact on the extraction accuracy of the cross-correlation algorithm are analyzed.The simulation experiments are conducted to analyze the impact of the noise of the output signal of the underwater detection light screen on the extraction time accuracy of the correlation algorithm.When the signal-to-noise ratio is lower than 5d B,the cross-correlation algorithm fails,therefore,an effective signal extraction algorithm needs to be researched to improve the signal-to-noise ratio of the output signal of the underwater light screen.(2)The target detection model of the underwater detection light screen is constructed and simulated.Based on the optical properties of underwater light transmission,the underwater detection light screen target detection model is constructed based on the Monte Carlo method,and the underwater light transmission rate and the signal-to-noise ratio of the signal are simulated.As the detection distance and attenuation coefficient of the water increase,the underwater optical transmission rate and the signal-to-noise ratio of the output signal all tend to decrease.(3)The extraction algorithm of the signal obtained by the underwater detection light screen is researched.For the original underwater detection light screen signal is the non-stationary and non-linear weak signal,the EMD-CPSD algorithm for extracting the effective signal of underwater detection light screen signal is proposed.The simulation experiments are conducted and it is shown that the algorithm can improve the signal-to-noise ratio of the signal,For original over-screen signals with a signal-to-noise ratio of less than 5d B,the signal-to-noise ratio can be improved by up to 15.76 d B.(4)The underwater verification experiment is conducted and the result is analyzed.An underwater detection light screen velocity measurement system is built to acquire the signal of the target passing through screens under different conditions,and the signal-to-noise ratio and velocity of the target are calculated.the accuracy of the constructed underwater detection light curtain target detection model and the effectiveness of the underwater detection light curtain over curtain signal extraction algorithm are verified.In this paper,an underwater light screen target detection model is constructed,the underwater light transmission rate and the signal-to-noise ratio of the target passing screen signal are simulated,and then the underwater experiments are carried out.Based on the characteristics of the low signal-to-noise ratio of the signal that underwater projectile passing through the screen,an EMD-CPSD based signal extraction algorithm for underwater detection light screen is proposed and the effectiveness of the algorithm is verified through experiments.