Design Of The Granaries Temperature And Humidity Monitoring System Based On The Fiber Bragg Grating

The food is the basic material for human survival, it is difficult to preserve for a longtime. To solve the contradiction between the seasonal of food production and the perennial offood consumption. Therefore, how to achieve the safe storage of food become a worldwideproblem. At present, the detection of grain of condition temperature cable main use of thethermistors which working principle is temperature changes lead to the resistance changges,but the shortcoming of the thermistor is poor of interchangeability, non-linear relationshipbetween temperature and output resistance. In order to obtain the distribution of thetemperature and humidity in the range of the granary precisely and stably, we designed ameasurement system of the fiber Bragg grating. Through the fiber-optic network the systemcan detect granary temperature and humidity in a wide range, and there is a linear relationshipbetween the measured temperature and humidity by fiber Bragg grating and the centerwavelength, so according to the function of spectrum linear frequence shift it obtained precisetemperature and humidity in the granary, that is the use of distributed fiber Bragg gratingsensor system to achieve real-time monitoring of temperature and humidity.The distributed fiber Bragg grating sensor system is a new sensor network, theconcatenation of multiple fiber Bragg grating sensors in an optical fiber, the operatingwavelength of each grating separated from each other after a3dB coupler reflection, and atthe same time then wavelength detection demodulation system to measure the wavelengthshift of the multiple grating to detect the corresponding temperature and humidity change ofthe measured point inside the granary. The sensitivity of fiber Bragg grating is also higher,can achieve real-time monitoring the granary temperature and humidity from the overall. Theexperimental obtained the temperature and humidity information by equipments, such asLPT-101light source, optical fiber with FBG encapsulated, magnification processing circuit,simulation granary, etc. We have no time to do the experiments to validate in humidity aspect.Use the Origin software to draw diagrams of the temperature and center wavelength, at thesame time compares the measuremented data with the K-type thermocouple as a standard.Deviation curve drawn shows fiber Bragg grating temperature close to the standardtemperature, indicating the high degree of accuracy of the measurement of this monitoring system to meet the requirements of the granary monitoring.