The first optical fiber system, which optically interconnects the first laser radiation source and the first optical detector with an emission end of the first optical fiber system, has the emission end disposed on the rotatable portion.

Disclosed are a method for controlling a transmission power in a multichannel system, a reception end, and a transmission end.

A light source may emit light that is conducted through multiple optical fibers, each having a source end and an emission end.

A resonator is positioned in the housing with a transmitting and receiving end facing the closed end of the housing.

In a mobile telephone terminal at the transmitting end, audio data to be transmitted are sequentially inputted, and it is determined whether the inputted audio data are silent.

To provide a wireless tag communication device having a simple structure that can remove sneak signals from a transmitter end.