Research On Ranging And Speed Measurement Technology Of Cooperative Communication Emitter Based On LFMCW System

Different from the traditional application context,this paper focuses on the problem of distance,velocity,and acceleration estimation of cooperative communication radiation sources using linear frequency modulated continuous wave(LFMCW)in a large dynamic range.The so-called large dynamic range mainly refers to the characteristics of the target with long range,high speed and accelerated motion.LFMCW ranging has a simple structure,high distance resolution,low detection probability(LPD),low probability of interception(LPI),and because the power spectrum of the LFM signal is almost rectangular in the modulation bandwidth,it is not easy to perform noncooperative interception.The LFM signal has a large bandwidth,and the range resolution is inversely proportional to the bandwidth,so LFMCW ranging has a good distance resolution;in addition,LFMCW ranging can measure not only distance,but also velocity and acceleration.In this paper,in view of the low signal-to-noise ratio in communication radiation source ranging,the ensemble empirical modal decomposition,wavelet denoising,and random resonance methods are investigated to improve the signal-tonoise ratio and thus provide the prerequisite for the subsequent accurate estimation of acceleration and velocity.Subsequently,the discrete polynomial transformation method is studied in response to the problem of estimating the acceleration and velocity.Firstly,the system of cooperative communication radiation source ranging and speed measurement is analyzed,the reasons for adopting the LFMCW system are clarified,the basic principles of LFMCW ranging are introduced,and the system’s ability to discriminate acceleration,velocity,and distance is analyzed under the guidance of fuzzy function theory.The spectrum is analyzed and spectrum leakage of parameter estimation theory,the causes of fence effect and how to avoid them are investigated,so as to provide a theoretical basis for the subsequent analysis.Secondly,to address the problem of low signal-to-noise ratio of communication radiation source ranging and speed measurement,a brief introduction to ensemble empirical modal decomposition denoising and wavelet denoising is made,and random resonance denoising is studied in depth.Since the random resonance phenomenon,which is achieved by adjusting the system parameters,corresponds to different parameters at different frequencies.In general,the frequency characteristics of the target signal are not known,and it is not possible to determine the parameters required for random resonance directly according to the frequency.To address this problem,this paper introduces the random resonance method of the African vulture optimization algorithm and the chameleon swarm algorithm to select the optimal system parameters adaptively.The convergence speed,simulation time and the maximum signal-tonoise ratio achieved by the output signal of the two adaptive stochastic resonance methods are investigated,and the stochastic resonance method based on the particle swarm optimization algorithm and the stochastic resonance method based on the ant colony optimization algorithm are introduced for comparison.Finally,for the problem of acceleration estimation,the effect of the presence of acceleration on the differential beat signal is analyzed.When acceleration exists,the Doppler dimensional spectrum of the differential beat signal is distorted after mixing,and if the acceleration is not estimated,the estimation performance of the velocity will be affected when the acceleration is small,and even the velocity cannot be estimated when the acceleration is large,which will also affect the estimation performance of the distance.LFMCW ranging is to estimate the distance,velocity and acceleration by estimating the parameters of the beat signal obtained by the mixing of transmitted and received signals.Acceleration estimation has always been an important and difficult point in the field of LFMCW ranging.In this paper,aiming at the problem of parameter estimation of accelerated moving targets,two new discrete polynomial transform methods,discrete polynomial transform based on RIFE algorithm(RDPT algorithm)and discrete polynomial transform based on CZT algorithm(CDPT algorithm),are proposed to solve the problem of acceleration estimation.The estimation performance and computational complexity of the two algorithms are analyzed and compared.