초록 ▼

An optical fiber cable with optical fibers surrounded by a first gas blocking layer which is surrounded by a second gas blocking layer spaced from the first layer so as to provide longitudinal gas flow channels between the first and second layers. The channels are filled with a gas under a pressure

An optical fiber cable with optical fibers surrounded by a first gas blocking layer which is surrounded by a second gas blocking layer spaced from the first layer so as to provide longitudinal gas flow channels between the first and second layers. The channels are filled with a gas under a pressure above atmospheric pressure so that when the second layer is punctured, there is a gas flow and/or gas pressure drop indicating such puncturing and hence, if caused by tampering, the fact of tampering. Also, devices for indicating the gas flow and/or pressure drop and alarms and/or signal transmission terminating apparatus responsive to such devices.

대표청구항 ▼

An optical fiber cable comprising at least one optical fiber extending lengthwise of said cable, a first substantially gas impermeable layer encircling said optical fiber and a second substantially gas impermeable layer encircling said first substantially gas impermeable layer, a viscous filler fill

An optical fiber cable comprising at least one optical fiber extending lengthwise of said cable, a first substantially gas impermeable layer encircling said optical fiber and a second substantially gas impermeable layer encircling said first substantially gas impermeable layer, a viscous filler filling any otherwise empty spaces within said first layer and said second layer having at least a portion of its inner surface spaced from the outer surface of said first layer to provide at least one gas receiving duct intermediate said first layer and said second layer which extends lengthwise of said cable.