Research On The Key Technology Of Long-distance Circumferential Detection System

The laser fuze is an active proximity fuze,which detects the target within a predetermined distance and detonates the warhead at the best bomb point.It uses narrowpulse laser detection,can accurately detect the distance and position of the target,has the advantages of high fuse efficiency and strong anti-electromagnetic interference ability,and is increasingly valued by military enterprises and scientific researchers.At present,laser fuzes are not only used in missiles,but also in low-cost conventional ammunition,such as artillery shells,mortars,and grenades.This subject uses conventional air defense munitions as the research background,and designs a laser fuze with narrow pulse,longdistance detection and 360° detection.The focus of this research is: the design of a narrow-pulse laser emitting system with high peak power and high repetition rate,the design of a high-sensitivity laser receiving system,and the design of a high-resolution time-to-digital conversion(TDC)system based on FPGA.This subject uses a laser diode,which power is 200 Watt,to generate high-power laser pulses.The designed pulse repetition frequency is 20 k Hz,which can realize the rapid detection of the target and reduce the distance error of the target.At the same time,the use of capacitor charging and discharging to generate instantaneous high current.Under the control of high-speed Ga N FET,the laser diode generates a laser pulse with a pulse width of 5 ns,which can effectively improve the ability of the laser fuze to resist cloud and fog interference.This topic uses an avalanche photodiode(APD)with fast response speed and high sensitivity to detect weak laser echo signals less than 100 n W.A low-noise preamplifier circuit is designed to convert the weak current signal detected by the APD into a voltage signal,and the main amplifying circuit is designed to amplify the echo signal without distortion.At the same time,the constant ratio judgment method is used to judge the echo time.This topic uses time-to-digital conversion(TDC)technology,and realizes the timeto-digital conversion function through Cyclone ? series FPGA.After testing,this type of FPGA can achieve time measurement with a resolution of 73 ps,which can achieve distance measurement with centimeter-level accuracy of the target.Finally,this subject conducted static and dynamic tests on the designed laser fuze.The maximum detection distance of the laser fuze was tested through static tests;the impact resistance of the laser fuze was tested through the Mahit hammering dynamic test,and the actual range detection effect of the laser fuze was verified through the dynamic range test.