Study Of Velocimetry For Sky Screen On The Blue Background Light

Projectile flight speed is a significant index measuring the performance of the barrel weapon, as well as the necessary parameter of weapon test. The target speed-measuring device consisted by two sky screens and a electrical chronometer are widely applied in the projectile speed-measuring field. For the photoelectric detector is relatively weak in detection sensitivity in blue light wave band, sky screen cannot be applied reliably in plateau at present. In this paper, the study on improving technology of sky screen sensitivity in blue background light is carried out and the double-light-curtain detection plan is proposed, which can meet the demand for the speed measurement of the sky screen in plateau.The plan of improving the sensitivity of sky screen in blue background light is designed, and dual-shot sky screen solution is proposed. Two sets of independent conversion modules of photoelectric detector are used to form two coincided probe screens in space. When the projectile goes across the light curtain, two modules would output the signals independently, and the signals would carry out the synthesis by signal processing circuit in the behind, which would output the projectile flight signal effectively at last. The circuit mainly includes the signal synthesis circuit, programmable gain circuit, post amplification circuit and drive output circuit, the circuit gain can be adjust in real time According to the change of external environment.In order to satisfy the test requirements of the projectile flight time, the multi-SCM distributed control is proposed to realize the wide-range time electrical chronometer.The host microcontroller is connected to two pieces of CPLD to achieve dual-channel-measuring functionin independently. Two slave microcontrollers are used to receive data and display from the host microcontroller respectively. So the technical requirements of the measurement range of chronometer is realized.In order to simulate the blue background light test environment, the blue plane light simulation test environment is installed indoors, and the blue background with optical filter in outdoors. The live test is conducted in two environments respectively. The sensitivity of tester declines drastically. The contrasting test is carried out for dual-shot sky screen and JYJ-90 type sky screen, and the sensitivity of the dual-shot sky screen in blue background is basically the same as the JYJ-90 type sky screen in natural light. Measuring the electrical chronometer with dual-channel signal generator,the paper draw a conclusion that the electrical chronometer’s measurement range is not shorter than 20s, and the relative error is not greater than lppm, which can satisfy the large-scale time interval demand. According to the test, the designed dual-shot sky screen and electrical chronometer can reach the requirements of technical index.