Abstract: A baseband signal processing unit changes the collector current of a transistor (20) formed by a bias control circuit (7) in accordance with a baseband transmission signal input from a baseband signal input terminal (18), changing the drain bias of a high-frequency transistor (1) to realize frequency modulation by changing the oscillation frequency, and the radiation wave thereof forms a transmit RF signal, whereby the transmission operation is performed. On the other hand, the oscillation signal is synchronized with a frequency modulated RF signal that arrives from outside, the change in frequency caused by the frequency modulation is generated as a change in the drain bias of the high-frequency transistor (1), and reception operation is performed by taking out that change as a voltage amplitude change from the baseband signal output terminal (14). As a result, it is possible to provide a microwave/millimeter wave communication apparatus that is simple in structure, low cost, and low power consumption.

Abstract: A fiber fuse detecting apparatus provides early detection of a fiber fuse generation in an optical fiber that propagates laser light, preventing the damage from expanding. It comprises light input means arranged on a laser light incidence side of the optical fiber that inputs at least a portion of reverse direction propagation light propagating in a reverse direction to light incidenting the optical fiber, light receiving means that photo-electrically converts light input by the light input means, electric filter means that extracts from an output signal of the light receiving means a prescribed frequency band component that contains a periodic signal due to fiber fuse, detecting means that detects change of or a prescribed value in output level of the electric filter means, and warning means that emits a warning signal in response to a detection output of the detecting means. The laser light to the optical fiber is stopped or reduced by means of the warning means.