Fiber Bragg Grating Intelligent Perimeter Security Method And Key Technology Research

Perimeter security is the first line of defense to protect critical facilities and assets, effective perimeter security technologies and methods can eliminate or reduce the threat from the outside world. With the continuous development of society, people increasingly strong demand for efficient security defence.The most widely used, the longest history year-old traditional electric infrared security products are radios, leaked cables, electronic pulse fence and so on, They are outdoor active, susceptible to electromagnetic interference, and vulnerable to the weather, the environmental impact, the false positive rate, addressing inaccurate. Emerging fiber optic perimeter security technology including the use of backward scattering of the optical time domain reflect meter positioning technology (ODTR) and interference technology based fiber perimeter Positioning System. Positioning the ODTR of multi invasion analysis is complex, it is difficult to accurately locate. The perimeter of the technology based on the principle of interference is a phase modulation type. It’s the polarization state of the incident light and the outside influences are more sensitive to the high rate of false positives, precise positioning is also it’s problems. In face of perimeter insurmountable challenges and urgent needs of the security market, we propose a perimeter security method based on fiber Bragg grating (FBG) sensing technology. FBG perimeter security method using the FBG wavelength modulation, has a strong ability to reuse. It can simultaneously determine multi intrusion and achieve multi-point accurate addressing, it is outdoor passive, anti-thunder and lightning, anti-electromagnetic interference, intrinsically safe, small size, corrosion resistance, etc. Particularly suitable for field laying perimeter to prevent the application to meet a variety of complex environment, it is a new perimeter security methods. At home and abroad is still first.In this paper, the new method based on FBG perimeter security and the key technology to do in-depth study and research work are as follows:(1) Based FBG sensing technology, perimeter security methods, combined with modern perimeter security perimeter of the overall requirements, the FBG security key technologies and key issues to be addressed are refined, given FBG application to the perimeter security overall security model, in accordance with low to high levels divided into physical layer, layer, algorithms, and application layers, and analysis of the key technical issues for each level. The feasibility of this method is demonstrated in detail from intelligent addressable IntelliSense, weather resistance, reduce costs aspects.(2) In order to further investigate the intrinsic relationship of perimeter intrusion FBG sensing, based on the principle of FBG sensing, especially the FBG wavelength with temperature and strain relations, combined with single-particle elastic rope vibration theory, design a FBG vibrating mathematical model and structure model theoretical analysis and calculation, the general relationship of the impact of various structural parameters on the vibration displacement and natural frequency of the entire system. According to the analysis, we design experimental program, the establishment of the experimental apparatus, the experimental results verify the correctness of the model calculations, and at the same time to determine the specific structural parameters of the sensing unit to further improve the performance of the sensor through the package, to meet the perimeter security requirements on the performance parameters of the sensing unit.(3) on the basis of FBG sensing unit, we proposed "identical FBG vibration security "concept applied to regional security, each regional security with the same wavelength FBG vibration sensor unit can achieve precise addressing of each zone, existing demodulation capability case, the expansion of the capacity of each of the optical path in a sensor network, analysis the isotactic vibration monitoring method to achieve security theoretical and practical operability, verified by experiment, although the sensor in use isotactic the process there will be varying degrees of sensitivity loss, but still meet the perimeter security requirements of the sensor unit, and with the actual operability.(4) We have to achieve a distributed detection based on the FBG vibration sensing perimeter security defense. FBG vibration sensor is a wavelength modulation type, belonging to a point-to-point detection. The various FBG sensors can only detect the physical location of the sensing unit parameters, quasi-distributed detection can only be achieved through intensive sensing probe points. Here we want to apply the FBG vibration sensor distributed detection perimeter security, that the invasion at any perimeter security point, the system should respond it, absolutely prohibit the emergence of security "blind spots". This is essential for perimeter security. But For FBG other sensors, it is impossible to achieve. Based on wavelength division multiplexing principle, we establish the FBG vibration of cable optical passive sensor network. Design approach of the different installation media installation is given to experimental methods suitable sensing element spacing for each installation. Practical application to verify that this method is very effective, but realize the distributed security monitoring based on FBG vibration sensor.(5) The another key technology is how to improve the security alarm accuracy. Through dynamic extraction of the reference value in the time domain to obtain the correct starting point for the invasion, the invasion suspicious signal lock by time fragments division, statistics, marked, effectively shielding the ambient temperature and the outside interference of system influence. In the frequency domain, we present the fast Fourier transform (FFT) method, a single peak detection method. This method is the time domain pre-alarm sensing signal to the Fast Fourier Transform, for analysis and comparison with human intrusion signal and found the sensor self-vibration phenomenon of a single peak, thus effectively filtered out natural vibration false alarm due to external vibration disturbance, so that the alarm accuracy to obtain further assurance.(6) We put forward one novel perimeter security intrusion recognition algorithm based on time-frequency analysis. By analyzing the signal frequency, and duration of action of human intrusion reflect on the signal in time domain, application windowed Fourier transform (STFT) time-frequency analysis method, we give the corresponding window function, the window length, thereby determining the time resolution and the frequency resolution. The peak time-domain binding STFT frequency energy integral method can be used for the identification of the invasion. This algorithm can make the false negative rate of intrusion events tends to zero, while significantly reducing the false alarm rate.Through the study of the subject will be an effective solution to the field of traditional perimeter security the high rate of false positives, and cannot accurately addressing, vulnerable to the environmental impact, the installation of complex issues such as, effectively improve the technical level of China’s Public Security.