| Ultrasound technology is based on physics,materials science,electronic science,information science and other disciplines,and is widely used in medicine,industry,military,daily life and other fields.The study of the propagation of ultrasound in the medium and the study of ultrasonic effects are the theoretical basis for various applications.It is a very critical issue in this theory to maximize the efficiency of the ultrasonic transducer to produce an ultrasonic sound field that can be precisely regulated and meet the needs.The current mature method is to accurately control the ultrasonic sound field distribution by using phased array technology.Among them,the demand for portable multi-channel ultrasonic excitation equipment with large parameter adjustment range,high precision and high power output is urgent.In this paper,a portable multi-channel ultrasonic adjustable pulse scalable excitation module is designed and implemented.Each module can work independently,and can realize multi-module cascade expansion into a multi-channel ultrasonic adjustable pulse excitation platform.The module includes an ultrasonic excitation unit composed of a high-voltage digital pulse generator,a pulse signal control unit composed of an FPGA+Nios II soft core CPU,a human-machine interaction unit mainly composed of a touch screen,and a module cascade unit composed of synchronization signal control.And five parts of the power supply unit.The software design of the system mainly consists of two parts,one is the PWM transmitting module written by Verilog program,the external signal frequency detecting module and SoPC embedded hardware system,and the other is the user program of Nios II soft core processor written by embedded C language.Design two parts.In this paper,8-channel 0-100V adjustable and 4-channel 0-200V adjustable pulse excitation modules are designed respectively.Both modules can realize independent control of each channel.The pulse cluster of each channel can be adjusted from single pulse to continuous wave.Parameters include center frequency(10KHz-10MHz),pulse cluster repetition frequency(100Hz-1MHz),duty cycle(0.001%-100%),number of pulse bursts in the pulse cluster(1-105),phase control(delay accuracy)Up to ns level),pulse amplitude(0-200V),single channel continuous working time can be set(0-20 hours).Based on the research of ultrasonic generation and excitation principle,the hardware circuit design,software program design and system integration scheme of ultrasonic adjustable pulse excitation module are determined.Through the pulse signal performance test and module cascade test of the module,the results show that the excitation pulse frequency of each channel of the module can be adjusted,and the excitation pulse amplitude can be accurately controlled.Each channel can refer to the first channel as the reference and the phased array according to the set phase.The excitation,phase control parameters can be continuously changed,and the duration of the pulse excitation can be set to meet the expected design criteria.The modules can be cascaded into a multi-channel ultrasonically adjustable pulse excitation platform through a synchronization signal.The device has portable,multi-channel transmission,wide-range parameter setting,and can realize the adjustment from single pulse excitation to pulse cluster to continuous wave,providing a reliable and expandable portable ultrasonic excitation module for various scientific experiments that require ultrasonic excitation with broadly application foreground. |
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