Power aware air quality sensing system with efficient data storage capability

Abstract

Introduction: This paper presents a portable device of Air Quality Monitoring System (AQMS) based on a sensor platform. The purpose of the study is to power awareness, warning indication, and minimal data storage capability. Materials and methods: AQMS is developed by embedded design methodology. The software part is based on the C programming language. AQMS device is made up of “transmitter” and “receiver” sections through the Zigbee wireless network. The objective is to collect concentrations of CO, NO2, CO2, humidity, and temperature to check air pollution for health awareness. A power-saving strategy is adopted in the "transmitter" of AQMS through a Demultiplexer circuit. To minimize the space complexity of storage and availability of long-term data, data encoding techniques are implemented. Results: By implementing switching activity on the sensors in AQMS, the active mode of sensing operations are controlled and a power saving of 18.41% is achieved. Extending the duration of transmission operation increases data storage in the “receiver” unit. Hence, two encoding techniques are developed where real-time data are encoded in binary form: 2-bit encoding and 3-bit encoding. According to the results, 2-bit encoding saves 50% of storage space and 3-bit encoding saves 25%, compared to not utilizing any encoding strategy, sacrificing data accuracy by less than 5%. Conclusion: AQMS design is created with the implementations of low power consumption and low storage. Additionally, an alarming condition is set in AQMS for indicating the level of pollutants in the air to determine the risk level of exposure which is dangerous for human health.

Keywords

• Air pollution; Sensor; Wireless network; Low power; Data encoding