Research On Multimode Effect Of Velocity Measurement Of In-bore Moving Target Based On Doppler Method

Among the parameters of the inner trajectory,speed and acceleration are very important parameters,which reflect the mechanical characteristics and ammunition characteristics of the target object,so the test of the moving speed is of great significance for the research of weapon systems.When using millimeter-wave Doppler radar to measure the speed of a moving object in a small-caliber tube,for example,the speed of the projectile in the barrel,it is found that the echo signal obtained in the barrel has been processed to obtain two speed curves,and the cause is analyzed.There is a problem of Doppler frequency ambiguity.Aiming at this problem,this paper proposes the conjecture that Doppler frequency ambiguity is due to the existence of multiple modes in the waveguide.This conjecture is verified through theoretical derivation and design experiments.The innovative work of this article mainly includes:(1)Aiming at the problem of speed solution blur in the speed measurement of the target object in the small-diameter tube,the cause of the problem is analyzed by Doppler frequency blur,and the cause of Doppler frequency blur is proposed by the multimode effect guess.(2)This paper analyzes the difference between the Doppler principle in free space and restricted space,combined with the waveguide theory to analyze and derive the transmission characteristics in metal pipes,and obtains the parameters of different modes that cause multimode effects,Provide a theoretical basis for the conjecture proposed in this article.(3)In order to verify the correctness of the theoretical derivation,this paper also designed a verification experiment.In the course of the experiment,in order to facilitate the analysis and to draw a more accurate conclusion,the method of control variables was used to verify the effect of the multimode effect on the Doppler frequency.An experiment at a uniform speed was designed to verify,by analyzing the experiment The data processing results verified the correctness of the theoretical derivation,and finally found two modes that affect the Doppler frequency under experimental conditions,namely TE22 mode and TE11 mode.This paper studies the multi-mode effect of velocity measurement of the moving target in the bore from two angles of theoretical derivation and experimental verification,and briefly summarizes the measurement method of the target velocity in the bore under the multimode effect,which provides a direction for the next research.