Research On Key Technology Of Calibration System For Coil Target

The coil target is a common used zone-block device for measuring projectile’s velocityin domestic shooting range. Although it has undergone an evolving process, the errorsometimes happens when used and need to be calibrated. At present, there is no calibrationsystem for the coil target in the domestic shooting ranges. This thesis researches the keytechnology of the calibration for the coil target and the results can provide the basis for thecorrection of the coil target system, so it has practical significance.On the basis of the speed principle and the induced electromotive force model of the coiltarget, this paper analyzes the characteristics and influence factors of the induced signal ofcoil target and puts forward the whole design scheme of coil target calibration system. Thewhole calibration system which is made of the time-scale signal generator andelectromagnetic generator calibrates the coil target by outputting the excitation signal oftime-scale signal generator to electromagnetic generator, then the induced signal of the coiltarget is generated and transported to the timing instrument.According to the features of the induced signal, the time-scale signal generator whoseoutputs are dual-way sine voltage signals is designed. CPLD controls the programmable gainchip and the external memory for adjusting the amplitude and the frequency of the dual-waysine voltage signals. By using the software technology of CPLD for dividing frequency, theinterval of dual-way sine signals can be adjusted and the accuracy reaches 0.1μs. In order tomeet the requirement that the current of the electromagnetic generator as load is high, the laststage power amplifier circuit is designed. The technology of the voltage-controlled voltagesource low-pass filter is used for improving the signal-to-noise ratio of the output signals.This paper analyzes the impact of the diameter and the circle number of internal coil ofthe electromagnetic generator on the induced electromotive force of the coil target and analyzes the impact of the frequency and the amplitude of the excitation signal on the inducedelectromotive force. Based on the comprehensive consideration of the amplitude anddeformation degree of the induced signal and the load ability of circuit current, theelectromagnetic generator is designed. At the same time, the paper concludes that thefrequency of the excitation signal determines the induced signal’s frequency and influencesits amplitude. The amplitude of the induced signal is proportional to the amplitude of theexcitation signal under the same excitation frequency.Finally, the indicator of the calibration system is evaluated through the field experiment.The experiment of the calibration is conducted in a domestic shooting range and the data ofthe experiment is analyzed. The results of the experiment can provide the basis for thecorrection of the coil target system.