Design Of The Portable CTDT Measurement System For Seawater

With the development and utilization of the ocean in many countries,our country also regards the ocean development as an important part of the development strategy.Various phenomena and processes in the ocean affect the survival of marine life and human activities at sea.Nowdays,in the wake of developments in modern technology,the single parameter measurement instrument can not meet the needs of the developers,and the multi-hydrological parameter measuring instrument has become a new choice.In this paper,a portable seawater temperature and salt depth turbidity measurement system is designed,which can measure the temperature,conductivity,pressure and turbidity of seawater,and send the data to PC through the serial port.This paper analyzes the measuring principle of temperature,conductivity,pressure and turbidity,introduces the methods used in this paper,and designs the measuring circuit and signal processing circuit of four parameters,also selects the main controller as the control unit of the system,it is used to measure the transmission and receiving of the result.In order to reach the purpose of modularization and configurable design of the measurement system and make each measurement system work independently as a separate measurement system,each measurement system uses a separate processor.ADuCM360 is chosen as the respective A/D conversion and control unit of temperature and pressure measurement system.TMS320F28377 S is chosen as the ADC and controller of turbidity and conductivity measurement system,and STM32F769 is used as the main controller of the system.For signal acquisition,the acquisition circuit for temperature measurement,the excitation and receiving circuit for conductivity measurement,the constant current source excitation and measurement amplifier circuit for pressure measurement,the LED excitation circuit for turbidity measurement and the receiving circuit are designed.In addition,the power supply circuit,communication circuit,storage circuit of main processor and real-time clock circuit are designed for the communication of the system.In terms of software,the program of main control system and measurement subsystem is designed,including ADC acquisition code,communication code,and parsing and executing code,storage code and so on.The temperature,conductivity,pressure and turbidity of the sensor are calculated in their respective processors after the sensor data are collected by using the ADC acquisition program,and the results of temperature,conductivity,pressure and turbidity are obtained.After data acquisition,the calculation results are sent to the main controller through theRS232 interface.After receiving the data,the main controller chooses whether to store the data in the FLASH or upload the data to the PC directly according to the command.Through the final debugging,the function of the system has been completed,the purpose of measurement has been achieved and the requirement of measurement has been met.