# An Intelligent Wireless System for Field Ecology Monitoring and Forest Fire Warning
## 2 Design of the Monitoring System
### Design of Online System Hardware  
The hardware of the field ecological monitoring station in forest regions is comprised of data acquisition units, a power supply system, sensor groups, Beidou Satellite communication modules, GPRS communication modules, and mechanical towers, as shown in Figure 2.  
The data acquisition unit is the data processing and control core of the whole field ecological monitoring station, composed of a central processing unit, a display circuit, a storage circuit, a data acquisition circuit, etc. The data acquisition unit can acquire the analog or digital signal output by each sensor and complete data transmission through the Beidou Satellite as required by users. The central processing unit of the data acquisition unit uses the ATMEGA2560 single chip microcomputer of the ATMEL Company. The central processing unit completes the parsing of the original data from each sensor, the conversion of the data communication format, the conversion  
Figure 2: Block diagram of the system hardware. of the data display format, the conversion of the data storage format, the monitoring of the sensor operation mode, the monitoring of the satellite and GPRS communication mode, and the monitoring of the power supply mode and achieves automatic reset following operator errors via the watchdog circuit. A color monitor is used for displaying the monitoring data and status data. The data storage circuit uses an SD card with a storage capacity of 8 G for locally storing monitoring data, allowing for manual data copying and erasing at regular intervals. The data acquisition circuit uniformly converts a 0-20 mA analog current signal and a 0-5 V analog voltage signal output, using the sensor group, into a 0-2.5 V analog voltage signal and is connected to the AD conversion interface of the single chip microcomputer after amplification and filtering. The IO interface of ATMEGA2560 acquires the switching value output via the precipitation sensor. The PWM interface acquires the output of the wind speed sensor. The communication module of the Beidou Satellite uses the GYT2015C Beidou Satellite data transmission module. The data transmission module has the Beidou Satellite communication and Beidou Satellite positioning and timing functions and is connected to the central processing unit via the RS232 interface, with a transmitting power of 10 W. The communication module of the Beidou Satellite is installed on the mechanical rack for providing the communication link of the Beidou Satellite for the field ecological monitoring station. The system reserves a GPRS communication module interface for use in the regions with mobile phone signal. The sensor group can measure the parameters of soil, atmosphere, light, and plants in the ecological microenvironment in forest regions in real time. The major sensor configuration and properties are shown in Table 1. Users may increase or decrease the number of sensors as necessary. The power supply system is comprised of a solar energy and controller, a 75 Watts polycrystalline solar panel, and a 12 V 65 A-h gel energy storage battery and provides a 12 V direct current for the field ecological monitoring stations. A 220 V alternating current power supply can be used for the forest where mains supply is available. The energy storage battery is placed in an underground water-proof box and buried 0.5 m below the soil surface under the mechanical tower for anti-freezing protection. The mechanical tower is made of stainless steel, fixed with stainless steel wire ropes for wind protection, and provided with a lightning conductor, with its foundation fixed by heavy concrete blocks. The mechanical tower is equipped with atmosphere parameter sensor groups, light parameter sensor groups, Beidou satellite and GPRS data transmission modules, and solar energy panels at the top. The mechanical tower is equipped with a stainless-steel rain-proof box in the middle and other