Budapest University of Technology and Economics Department of Electron Devices

1. Case study of a simple, low power WSN implementation for forest monitoringZoltán Gy. Kovács, Gábor E. Marosy, Gyula Horváth Budapest University of Technology and Economics Department of Electron Devices BelAmI2 Miniconference March 1, 2011, Budapest, Hungary

2. Introduction • Motivation • The project is supported by the NAP-08 OMFB-00736/2005 BELAMI_H project of the Hungarian National Office for Research and Technology. • Project aim based on forest fires statistics in Hungary • Considerations: • Wireless sensor network for environment monitoring • The WSN shall be a stand-alone system • It should provide additional information for an existing system • The system should be cost-effective • Lower the maintenance time during the life-cycle • Main questions of the development: • In-situ measurement or remote sensing • Deciding the parameters that must be measured • Deciding the time and cell resolution for the protected area BelAmI

3. Hungarian wildfire statistics • The number of the events and the level of the destruction have risen. • In 90%, the reason behind a fire is carelessness or arson. • The greatest destruction is caused by arson. Wildfires in 2008. • Preventing wildfires • Early recognition • Effective localization • Suplementary weather information • Fast and continous monitoring BelAmI

4. Monitoring systems • Observation from space • Pro: Large areas can be observed • Con: High cost, limited time • Aeroplane or UAV • Pro: Medium area • Con: Weather dependant • Camera based systems • Pro: Medium area • Con: Weather dependant • Sensor Network • Pro: In-situ and realtime measurements • Con: Small area, localized Smoke BelAmI

5. Predicting Wildfires The current weather conditions have a significant influence on fire behavior, that is why the weather forecast service may provide some extra information. • Three conditions needed for the formation of fire: • Inflammable material • Oxygen • High temperature • Main sources of wildfires: • human carelessness • fire-raising • natural sources • Gas sensors for early detection offire: • Carbon monoxide (CO), • Carbon Dioxide (CO2), • Methane (CH4), • Ethanol (CH3CH2OH) • Nitrogen Dioxide (NO2) BelAmI

6. System level diagram SN SN SN SN SN SN SN SN SN SN SN SN RN RN BN • Three main components: • Sensor node (SN) • Relay node (RN) • Base node (BN) • Communication between nodes: • SN-RN: ISM band radio • RN-BN: GSM based • Main properties: • Scalable system • Database backend (SQL) • Operator can be notified via SMS • During SN deployment GPS coordinates are assigned to Node ID-s BelAmI

7. Sensor Node (SN) - Hardware setup COM Unit Power Supply Unit MCU Unit • Power Supply Unit (PSU) • Primary energy source: Solar array • Secondary energy source: LiPoly battery • Integrated battery charger • LDO for voltage stabilization • Microcontroller Unit (MCU) • eXtreme Low Power PIC18 MCU • 8-bit controller • integrated AD converter and SPI interface • Sensor Unit • Temperature sensor with ± 2oC accuracy • IR Smoke detector • Optional: Relative Humidity Sensor • MAC address chip • 48-bit Unique Identifier • Used for product tracking SolarCells SPI TXRX Battery DC/DCConverter MCU Sensors SignalConditioning ADConverter Sensor Unit BelAmI

8. IR Receiver IR Transmitter Scattering effect Detector Chamber Sensor Node (SN) - Hardware setup • Communication Unit (COM) • Silicon Labs Si4432 ISM band single-chip transceiver • Compatible with EZMAC and Zigbee protocols • We implemented a simple, point-to-pont radio connection between RN and SN • Sensors for detecting fire: • Temperature sensor • Reflection based IR smoke detector • Packet format for the communication • 4 bytes Preamble (0x55) • 4 bytes Synchronization word • 1 byte packet length • 2 bytes for FROM and TO fields enables network partitioning and fast filtering Preamble SyncWord PacketLength From To Cmd Param CRC 4 4 1 2 2 1 0..8 2 16..24 bytes BelAmI

9. Description of the Sensor Node (SN) • Power Consumption Antenna Power Supply Box (IP65) Radio Unit MCU Unit Sensor Unit GasChamber BelAmI

10. Description of the Relay Node (RN) COM Unit Power Supply Unit MCU Unit SPI ISM Antenna GSM modul TXRX Battery DC/DCConverter MCU ISM Radio modul UART TXRX MCU & Power modul GPRS Unit GSM Antenna Point-to point connection among the RN and SN units RN registrates the corresponding SN-s The neighbouring cells are operating on different frequencies. Implementing repeaters Nearly the same HW for all nodes to reduce cost BelAmI

11. Description of the Base Node (BN) Power Supply Unit MCU Unit Battery DC/DCConverter MCU UART Protocol Interface Ethernet orUSB TXRX PC Link Unit GPRS Unit Identical HW design with the RN PC interface (USB or Ethernet) Battery or USB powered JAVA based Human-machine interface under development MySQL database backend for event logging BelAmI

12. Future plans • Sensor Calibration • Wireless Network test and Optimization • Field Testing and long term testing • Connection to the weather forecast network • Extra sensor integration may be considered: • RH Sensor • Noise / Chainsaw detector BelAmI

13. Thank you for your attention! Questions are welcome! BelAmI