Another obvious problem is waveform distortion received by substation. By pulsing matching resistor at both ends of RS485, waveform is improved. It is shown in Figure5.
A large number of test results have proved that data from code emitter can be detected by receiver and transmitted to monitor center at the rate of 100%, and the system is stable and effective.
V. CONCLUSION
Wireless sensor network would have great impact on industry and our daily life in 21st century. This paper presents a WSN project based on ZigBee technology which is to be used in coalmine industry. Hardware and software design of WSNs are described in detail. System tests prove this system can work reliably. Personnel position system based on ZigBee has great value in coalmine industry. It is sure to play a positive roll in coal mine production.
Fig.5 Improved waveform
REFERENCES
