Study Of Fiber Optic Perimeter Protection System Based On Mach-zehnder Interferometor

Fiber and fiber optic sensor have good immunity to electromagnetic interference,extremely corrosion-resistant，and electrical insulation properties. Fiber optic sensorshave high resolution and sensitivity. With the continuous development and progress ofthe optical fiber sensing technology, it has been successfully used in perimeterintrusion detection and prevention field. Fiber perimeter to system is widespreadconcerned because of its superior environmental adaptability, and easy installation andmaintenance methods. At present, there have been a number of fiber optic perimeterprotection systems from different companies at home an abroad, based on a variety ofsensing structures. However, in the actual use, the positioning accuracy can not satisfythe increasing requirements. Because all of these, in this paper, the design of the fiberoptic perimeter protection system retains all the original advantages. And through theimprovement of the system structure and new positioning data processing methods,this system has improved the positioning accuracy and speed of operation. The maincontent of this article include:This article introduced the perimeter protection system’s practical application inrecent years. A brief analysis on the perimeters system generally used at home andabroad is made, which is indicated that fiber optic perimeter protection system has agreat future. There are theoretical analysis of Sensing principle of the optical fibersensors and fiber optic transmission principle. And a variety of interferometerstructures were analyzed including the advantages and disadvantages. On this basis,the fiber optic perimeter protection systems based on double Mach-Zehnderinterferometer is present. And this article demonstrated the feasibility of the program.Through the disturb experiment, the typical signal of outside world invasion is got.Modified double Mach-Zehnder interferometer phase detection is used in gettingsignal in combination with correlation algorithm. The using of correlation algorithm inlocation is introduced in details. The simulation verified the possibility of this method.If the same signal with different time delay were analyzed using correlation algorithm, the location of maximum value will be obtained. Through the location of maximumvalue, accurate time difference will be obtained. System’s location accurate is directratio to the AD convert speed. When set the AD convert speed as 20MHz,a theoreticlocation accuracy of 10.22m is received. A new method of processing signal piecewiseis present. Using this method can reduce the computational complexity on the base ofhigh positioning accuracy brought by the high sample rate. When set the AD convertspeed as 20MHz, a theoretic location accuracy of 10.22m is received. The computationspeed growth 8 times.