A radiation-curable fiber optic coating composition for an inner primary coating includes a coloring agent, preferably a dye or a dye precursor, compatible with the fiber of the fiber optic and capable of imparting a pre-selected color to the inner primary coating, or another coating. The lock device is mounted on a display unit of the electronic apparatus. There are as many sections as the tower require as per specific design. According to the invention, a correction signal, periodically modulated in a second frequency, is supplied to a measuring circuit, and a phase drift between the emitted correction signal and the correction signal processed by the measuring circuit is measured, the phase drift being caused by the measuring circuit. The determining may include comparing network statistics of the first path with network statistics of the second path, the network statistics comprising at least one of packet loss on the path, errors encountered via the path, and congestion on the path.