Design And Implementation Of Active Sonar Target Simulator

Target simulator is an indispensable auxiliary equipment in the development and debugging of sonar.In this paper,an active sonar target simulator is designed for assistant sonar test.It has two simulation modes:one is to transmit the preset target echo signal after detecting the active detection signal;the other is to collect the received signal in real time and delay the transmission after processing the received signal.Based on the hardware platform of TMS320C5517,the sonar target simulator is designed and implemented,the signal detection algorithm is simulated and analyzed,the corresponding software program is developed,and the function of the hardware system is debugged.Finally,the main functions of sonar target simulator are verified by pool experiments.Firstly,based on the characteristic information carried in the target echo,the simulation scheme of target strength,range,geometric characteristics and motion speed is designed according to the characteristics of signal fluctuation,time-domain broadening and Doppler frequency shift in the echo signal.The geometric highlight model is used to simulate the geometric characteristics of the target.The corresponding highlight echo signal is generated according to the geometric shape of the target.The scale information of the target is simulated after time domain superposition.Then the hardware platform of the target simulator is designed based on TMS320C5517,which mainly includes DSP and interface module,data storage module,power supply module,digital-to-analog conversion module and analog-to-digital conversion module.The process of receiving,processing and forwarding signals in the target simulator is analyzed,and the specific implementation circuits of each circuit module are designed.In the data storage module,the direct memory access controller is used to realize ping-pong cache,which ensures the efficient and continuous data flow to meet the real-time processing requirements.In the software design of the target simulator,corresponding real-time detection programs are designed for single-frequency signal and FM signal respectively.For single frequency signal,signal detection algorithm based on adaptive notch filter is adopted,envelope detection and width decision are used to detect signal and estimate delay value,and for FM signal,signal detection and delay estimation algorithm based on correlation algorithm is adopted.In order to overcome the problem of high sampling rate and large amount of real-time data processing,a copy correlator based on down-sampling technology is used to simulate and analyze the performance of the algorithm,and the corresponding software program is designed and debugged.Finally,the active sonar target simulator designed in this paper has been tested comprehensively,focusing on signal acquisition,real-time detection,echo signal simulation and other functions.Laboratory tests and pool experiments show that the designed target simulator can meet the requirements of indicators and functions,and the system has good reliability and real-time performance.It can be used to simulate the echo signal of active sonar target.