Robust Sensor Nodes to Monitor Carbon Monoxide and Natural Gas Levels - Embedded.com

Robust Sensor Nodes to Monitor Carbon Monoxide and Natural Gas Levels

The impact of pollution on the overall quality of life has been massive. Be it social or scientific, pollution has adversely affected all hemispheres of one’s life. The influence of Carbon Monoxide in such circumstances cannot be ignored. The impact has been felt greatly in the developing countries where the technological advancements are leading to increasing amount of Carbon Monoxide levels. To measure the levels, these countries require not only accurate but inexpensive methods of gas detection.

Many research reports have been published on the ways to do this. But previous designs have either lacked the degree of robustness required to operate in harsh environments, or do not have the capability to minitor a large number of nodes.

Effective real time pollution monitoring equipments require large number of nodes (preferably >50) which are capable of interaction and hence provide reliable information. Increasing the number of sensors increases the possibility of determining the exact amount of gas levels in the surrounding environment.

Hence the sensor nodes and the wireless network should together work cohesively to determine the correct levels of the gas desired to be monitored. Also it is important that the sensor node has low power consumption and is robust in extreme climatic conditions.

Our main focus is to develop many such sensor nodes and develop a simple protocol to effectively use them. In this paper we describe the design of a prototype which can test and monitor up to 50 sensor nodes for measuring levels of carbon monoxide.

To test the working our proposed design, we use the MSP430F2274-based evaluation module EZ430-RF2500 provided by Texas Instruments which also contains a CC2500 transceiver chip. The module contains a set of two target boards, one assigned as access point and the other as end device. The access point target board is connected to central computer system using a USB port. The USB port provides the power supply for the access point. The end device is powered by two AAA batteries, each 1.5V. The module EZ430-RF2500 has an inbuilt temperature sensor which provides accurate readings in the range of ±0.1oC.

The evaluation module also contains a software simulator (IAR embedded workbench) to debug and dump the code into the target boards. The module uses SimpliciTI protocol to develop RF communication among the target boards. The protocol can easily handle 100 nodes or more and hence is perfect for our particular application. The protocol provides with the option of using range extenders to increase the detection range of the target boards.

The range extension can be done up to 4 hops. The communication topology used in the SimpliciTI protocol depends upon the target boards which are active. If both the access point and end device are in ON condition, store and forward peer to peer protocol is used.

The ability of the sensor network to handle a large number of nodes will help in carrying out various processes of environment monitoring like reconstruction of pollutant flow and the density profiles of pollutants across the space. Hence the technique provides new opportunities to explore new ways of monitoring the gaseous pollutants, especially carbon monoxide in the air space.

In the same way any other parameter may be efficiently detected by developing an appropriate sensing node. Implementation of this technique will provide more insights on ways to improve the accuracy of the readings of the carbon monoxide sensor, while simultaneously keeping the cost factor to a minimum.

To read more of this external content, download the complete paper from the online open archives at the Global Journal of Research in Engineering and Electronics.

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