The Development Of Self-contained Temperature Conductivity Meter

The integrated system which includes sensor, signal processing circuit andencapsulation shell will be directly put into the bottom of the sea to detect the deep seaenvironment, because of the field work, it is more really reflect the sea situation, thismethod is more and more used in the study of deep-sea resources.This device with high sensitivity, low power consumption, self-contained as designcriterion, according to the special environment of2km under the sea, in combinationwith theoretical knowledge, from hardware and software two aspects, we design a kind oftemperature conductivity in-situ measuring instrument based on single chipmicrocomputer with C8051F320self-contained deep-sea sediment. The whole hardwarecontains integrated structure of sensor measurement principle and hardware design.Temperature sensor is made use of wide measurement range, high precision PT100platinum resistance or PT1000. Temperature measurement circuit is made use ofunbalanced bridge method, power supplies with constant current source, to improve theaccuracy of measurement. Due to the small signal voltage amplitude, we use theamplifier to enlarge small signal matching the voltage range of A/D circuit input analogvoltage. Here we use the measuring amplifier AD623. Conductivity measurementmethods is utilized with Four-electrode method (wenner method), to prevent polarizationof electrode, using100KHZ ac constant voltage power supply. By operational amplifier,precision rectifier filter circuit into a single chip microcomputer system for ADconversion and data processing; The System also is of EEPROM which stores data andthe USB interface. We select the communication mode for USB communication, as USBcommunication is fast, and in general use, plug and play, convenient and quick to uploadthe data to the PC. PC is mainly responsible for the collected measurement dataprocessing, display, management, and further analysis and research.The software is compiled with structured and modular design, and is of procedureand many independent function module, implementation of data acquisition, processingand storage, and upper computer communications. In USB communication programdesign process, we make full use of the USBXpress Development Kit’s the next bit machine firmware, device drivers and API functions, general PC dynamic link libraries,and write the PC application test, the temperature conductivity will be collected the datadisplayed on the PC.It is demonstrated in experiment results that the measurement index of systembasically meet the design requirements. This system is of simple structure, small volume,low cost, convenient operation, is easy to realize the deep resources of in situmeasurement.