Wireless Sensor Network fo a Radon Concentration Measurement System

Wireless sensor networks for environmental studies are the new frontier, extending monitoring capability in a cost effective and sustainable way, opening up possibilities of verifying and applying models and possibly leading to more reliable forecast, risk mitigation and action plans.
The measurement of radon concentration can also benefit from this concept, both for a large area network for outdoor and indoor measurements and for setting up local clusters of instruments for correlated monitoring in buildings with complex architecture, typically with public access (e.g. schools, hospitals, bank agencies). In the latter case, simultaneous hourly measurements in different rooms can help to spot and optimize remediation actions, often proceeding through an optimal tuning of the ventilation systems.
This thesis reports the architecture of a wireless module dedicated to the RADIM5b instrument, a low cost, high sensitivity instrument developed by JP-SMM, a Prague-based company
(http://www.jiriplch-smm.com/firm.htm).
The development of a module (RADIM+ in the following) implementing the data transmission between a cluster of RADIM5b and a web-server is based on WASPMOTE, a development platform by Libelium (http://www.libelium.com). WASPMOTE is based on the ZigBee (DigiMesh) mesh networking protocol, which is specifically designed for low-data rate, low-power applications. Moreover, the system can integrate:
- A module for a USB interface to the RADIM5B
- Sensor modules for temperature, humidity and pressure measurements
- A GPS module for geo-tagging
- A GSM (Global System for Mobile communications) / GPRS (General Packet Radio Service) module to enable communication by using the mobile telephone network.
Data from every instrument in the cluster are transmitted via the FTP protocol to a dedicated website, providing data validation, data reduction and reporting.
The communication between the web site and the network of devices is bidirectional, allowing verification of the status and control of every instrument in the cluster.
By the time of writing, the first module is being finalized and the skeleton of the web-server has been completed. The first tests of data transmission have been successfully performed and the first cluster is scheduled to be deployed for field tests in October 2012.