System Of A Large Area Of Farmland Soil Temperature Sensor Of Long Distance Fiber-based

Aiming at the development trends of agricultural and current state and practical problems of agricultural farming technique. This paper studies the influence of temperature on agricultural production, especially the direct influences of the cultivation layer soil temperature on agriculture. This paper studies the application possibility of emerging optical fiber sensing technology in agriculture, and analysis the problems of agricultural tillage technology and other conservation tillage methods, basing on the theory of optical fiber sensing conducted the study on system selection, According to the different temperature measuring principle of different optical fiber, it can be integrated with a variety of optical fiber sensing measurement system. Mainly analysis and comprised the characteristics of these kinds of system, and choose the most suitable distributed optical fiber temperature sensing system for application of large area farmland. Made an in-depth study on temperature measurement principle of optical fiber sensing system, analyzed the scattering phenomenon in optical fiber communication system, found the scattered light which contains the information of temperature, studied the physical relationship between the Stokes light and anti-Stokes light in Raman scattering. After calibrating the soil temperature sensing system, as long as measured intensity of Anti-Stokes and Stokes, can determine temperature value of each point of the distributed optical fiber temperature sensing system, so as to determine the distribution of temperature. By studying the characteristics of various kinds of temperature measuring principle, determine which optical fiber sensing temperature demodulation and measurement type is most suitable for large-area farmland temperature measurement. Studied on the optical time domain reflection technology, so as to ensure the temperature information of each point in the optical fiber system corresponds to the position information. Carrying the research and experiment on real-time temperature monitoring of large area and long distance tillage layer soil.This paper explains the key technology problems in the design of the system, and study the concrete implementation of the hardware, the system positioning technology, temperature demodulation technology, wavelength division multiplexing technology, and conducted research on procurement, testing and system integration of hardware in the system. This paper also introduces the technical index of the related hardware and software application development in detail, analyzed train of thought and method of temperature measurement system operating software. Based on research of the farmland temperature measurement system calibration method, summed up the specific experimental calibration method and A, B, K constant calibration formula and experimental method. Through experiments acquired a new calibration method applied in a large area of farmland. In addition to the realization of the real-time detection of temperature distribution in a large area of farmland soil, and the basic function of regular data storage, but also to achieve two main functions: constant temperature alarm and fault alarm. Fixed temperature alarm function which is a combination of crop three point temperature classifications based alarm value and indicates the geographical position of temperature. Fault alarm function is based on the acquired voltage of sensing cable which lying in the range of large area of farmland to judge whether there is worth strength cable fault or damage. Finally, carried on the system running continuously, and do research on the problem of the temperature drift of the system. After successfully solved the problem of temperature drift, made a comprehensive optimization on the temperature resolution, spatial resolution, measurement length, the measurement accuracy and system response time. Finally, realized the maximum measurement distance of the system is10 km, spatial resolution is up to 1m, the precision of temperature reached 1 Centigrade,and the system response time is less than 4s.