Abstract: A telecommunications optical fiber is secured against intrusion by detecting manipulation of the optical fiber prior to an intrusion event. This can be used in a non-locating system where the detection end is opposite the transmit end or in a locating system which uses Fresnel reflections and Rayleigh backscattering to the transmit end to detect and then locate the motion. The Rayleigh backscattering time sliced data can be stored in a register until an intrusion event is detected. The detection is carried out by a polarization detection system which includes an optical splitter which is manufactured in simplified form for economic construction. This uses a non-calibrated splitter and less than all four of the Stokes parameters. It can use a polarimeter type function limited to linear and circular polarization or two linear polarizers at 90 degrees.

Abstract: A telecommunications optical fiber is secured against intrusion by detecting manipulation of the optical fiber prior to an intrusion event. This can be used in a non-locating system where the detection end is opposite the transmit end or in a locating system which uses Fresnel reflections and Rayleigh backscattering to the transmit end to detect and then locate the motion. The Rayleigh backscattering time sliced data can be stored in a register until an intrusion event is detected. The detection is carried out by a polarization detection system which includes an optical splitter which is manufactured in simplified form for economic construction. This uses a non-calibrated splitter and less than all four of the Stokes parameters. It can use a polarimeter type function limited to linear and circular polarization or two linear polarizers at 90 degrees.

Abstract: A building monitoring system monitors selected zones in a building structure for the presence of moisture. The system uses multiple moisture detectors, each installed I the structure at a location to be monitored. A remote sensor unit is associated with each zone to be monitored and is coupled to the detectors in the associated zone. The sensor unit generates an alarm signal having a characteristic uniquely representing the sensor unit and any wet detector to pinpoint any leakage problem. A monitoring unit receives alarm signals from the sensor units, decodes the alarm signals and generates an alarm report reporting the existence and location of any leakage.

Abstract: A method and system of intrusion detection system for a multimode fiber optic cable. A light signal is launched into the cable fiber to establish a narrow spectral width, under-filled non-uniform mode field power distribution in the cable. A small portion of the higher order signal modes arriving at the remote end of the cable is sampled and monitored for transient changes in the mode field power distribution. The power distribution changes with physical disturbance of the cable. When those changes are detected as being characteristic of fiber intrusion, the system activates an alarm. This method can sense and alarm any attempt to access the optical fibers in a fiber optic communication cable. In preferred embodiments, the active signal of a multimode optical fiber is monitored for both signal degradation and transient power disturbance patterns that could indicate fiber damage or physical intrusion.

Abstract: A method and system of intrusion detection system for a multimode fiber optic cable. A light signal is launched into the cable fiber to establish a narrow spectral width, under-filled non-uniform mode field power distribution in the cable. A small portion of the higher order signal modes arriving at the remote end of the cable is sampled by use of a coupler and monitored for transient changes in the mode field power distribution. The power distribution changes with physical disturbance of the cable. When those changes are detected as being characteristic of fiber intrusion, the system activates an alarm. This method can sense and alarm any attempt to access the optical fibers in a fiber optic communication cable. In preferred embodiments, the active signal of a multimode optical fiber is monitored for both signal degradation and transient power disturbance patterns that could indicate fiber damage or physical intrusion.

Abstract: A trace wire is placed alongside an underground utility for long distance transmission of locating tones. The trace wire has a conductive core and an electrically insulating sheath on the core. The sheath has an outer layer of solid dielectric material surrounding the core, the outer layer having a predetermined weight per unit length and an inner layer comprising a solid foam of dielectric material filling the space between the core and the outer layer. the flexural rigidity ratio of the insulating sheath is given by: Frb/Fra?4 where: Frb is the flexural rigidity of the outer layer Fra is the flexural rigidity of a minimum outer diameter sheath of said solid dielectric material. This combination of a core conductor with insulating materials in a multi-layered design provides significantly improved properties over current commercially available insulated conductors when used as trace wires. In the presently preferred embodiment of the invention, the trace wire construction includes a. 1.