A striking tool is provided for interlocking with a bar-like tool having a fork end andor a pike end. The irradiation chamber is depleted of oxygen and oxygen containing gases, such as being drawn to a vacuum of 101 or greater Torr by a vacuum pump. A track structure is formed with the perimeter fa\xe7ade to retain a cable. In other words, two or more communication stations sequentially run in the interference avoidance operation mode in a time sharing manner. At the same time, the computing device monitors at least one other channel of the fiber pathway and identifies effects upon the other channel from the optical test signal. From this signal, a gross signal is determined, from which the number of rotations can be determined.