Design Of Multifrequency Signal Generator For Apple Wuality Nondestructive Testing

With the increase of apple imports in China,the number of demand for apple’s NDT is also growing.The apple quality nondestructive testing can increase products value and greatly enhance the competitiveness of Chinese apple export market.At present,domestic haven’t internal quality detection system for apple,so it is necessary to research on apple’s nondestructive testing device.In this paper,based on apple’s internal quality and the correlation of dielectric constant,design of multiple frequency dielectric for apple nondestructive testing device and measurement circuit,the signal generator and other function modules to complete measurement circuit design the precise measurement of the dielectric eigenvalue,multi-frequency signal generator is motivation part of the whole measurement system,and the measurement circuit is designed using the vector voltammetry measurement principle precision circuit,the device is mainly in order to achieve the high precision,intelligent part of the front end of the nondestructive testing equipment for measuring.This article mainly from apple NDT testing requirements,circuit design technology and the system module cooperation,performance contrast test these four aspects to carry out the study,thesis research content:(1)Analyzed the measurement requirements of the measurement object and designed the signal generator.According to the requirements,designed the measurement circuit that including the hardware design and software design.Contrast and select the appropriate chip for applied research,including signal generation module,digital-analog conversion module,analog switch module and other core modules.Select the STC89C52 as the control core of the entire measurement module.(2)The program-controlled multi-frequency signal generator based on STC89C52 and AD9850 chip is designed to generator the sine wave signal of 5 frequency points and the realization of sweep function in the range of 100Hz~5MHz.Design the corresponding filter circuit to the output of the sine wave noise processing to optimize the waveform,and with the human-computer interaction module to establish the system.(3)The measurement circuit for measuring the dielectric constant is designed.According to the corresponding measurement principle,the feasible measurement method is analyzed,and the equivalent series circuit and the equivalent parallel circuit are built by vector voltammetry.The measurement error of the measurement system is calculated.The measurement module circuit hardware,software debugging.Measurement of inductance,resistance and other data may affect the measurement results of the reasons for interference source analysis,the use of effective methods to reduce the measurement error and circuit interference.The design of the measurement module and the existing Apple data to compare the feasibility of the measurement system.