Design and Construction of an Embedded Telemetry System for Potentiometric Sensors
A new embedded telemetry system for potentiometric sensors was developed. The system consisted of a transmitter unit,a receiver unit and a personal computer( PC). The transmitter unit included a current amplifier,a Σ-Δ analog-to-digital converter( ADC),a microcontroller unit( MCU) and a radio module. The receiver unit was composed of a radio module,a microcontroller unit and a serial-to-USB converter module.The receiver unit was connected to an upper computer via a universal serial bus( USB). The embedded software written in C language controlled the signal acquisition and transmission. The computer software written in Lab VIEW language was used for data storage and display. The range of the acquisition voltages was from"1. 17 V to +1. 17 V. In order to verify the accuracy and reliability of this system,a control experiment had been done with this system and a digital multimeter. Moreover,a response test of acidity changes had been done with the self-made H+selective electrode. The results showed that the accuracy of this system could be up to 0. 1 m V and it had strong anti-noise ability. The square of the linear correlation coefficient of the response of the changes in p H values was 0. 998. The curve of the results measured by this system was consistent with that measured by the commercial electrochemical analyzer. The system was built with standard hardware components and the size of the transmitter unit was only 29 mm ×14 mm ×11 mm. It can be easily used for remote and real-time detection for the potentiometric sensor.