Analysis of OTDR-parameters for territorially distributed security systems

Optical Time-Domain Reflectometry (OTDR) method is attractive for fiber-optical security and monitoring systems due to the availability of such reflectometers and the well-known advantages of optical fibers. However, there are still limitations of this method which don’t allow reliable detection and localization of several nearby physical impacts on optical fiber. This is related to the ambiguity of the OTDR operating parameters, which vary for different. Therefore, it is necessary to analyze of the metrological reliability determining OTDR-factors of optical fibers parameters and establish of relationships between key probing optical pulses parameters. The dependencies of the maximum length of monitored fiber-optical line on the duration of probing pulse and averaging OTDR-time are established. The influence of the optical fiber length on the registered macrobend attenuation was also revealed. The obtained OTDR-limitations are analyzed. It is concluded that it is necessary to hybridization OTDR with optical radiation power meters to increase the reliability and completeness of controls in territorially distributed security systems. This makes it possible to select the most significant OTDR-parameters that affect on range and resolution when building fiber-optical security and monitoring systems for fiber-optical communication lines.