Fiber Optic Sensing System For The Internet Of Things Applications

The concept of Internet of Things was formally proposed by ITU in2005. Since that, coupled with the fully developed of related technology, Internet of Things becomes a research hot-spot. A typical system of Internet of Things is made of three parts.sensing layer, network layer and application layer. Now, the sensing layer is mostly composed of electric sensor nodes. For the past few years, with the development of optical information technology, fiber optic sensors sensors goes towards the market. Compared with electric sensor, fiber optic sensors have advantages of anti-electromagnetic interference, anti-noise, without the power supply etc.. So fiber optic sensors can be used in harsh environments, such as no power, underwater, underground etc..In this paper, we design the fiber optic sensing system for the Internet of Things applications with one sensor node. We use the fiber optic sensor system, whose light source is the distributed feedback fiber lasers (DFB-FL). We transfer the signal which carries the characteristics of external environment changes into the computer through Data Acquisition (DAQ) card. Then we realize digital phase generated carrier(PGC) demodulation in the computer through the virtual instrument Lab View. After that, we release the data which was demodulated based on the B/S structure, so users can monitor the environment of the sensors anytime and anywhere via typing the URL in the browser. The biggest characteristic of the system is no power supply and could be monitored anytime and anywhere. The main work and innovation are as follows:1. Researched the basic concepts and history of the Internet of Things;designed the fiber optic sensing system for the Internet of Things applications simply.2. Surveyed a variety of sensor technology; analysised the principle of why the DFB-FL can be used as a sensor.3. Studied the demodulation method of the fiber optic sensing system for the Internet of Things applications, especially focused on the demodulation technology of the system which used the DFB-FL as its light source; analysised the principle of the digital PGC demodulation based on non-equilibrium M-Z fiber interferometer; designed the block diagram of the system; realized the digital demodulation in the computer trough Lab View and restored the signal which was being detected.4. Analysised the data processing theory of the fiber optic sensing system for the Internet of Things applications, include data storage and release technology.5. Realized the data processing of the fiber optic sensing system for the Internet of Things applications; designed the two data release methods and realized separately, then made comparison.