Abstract: [Problem] To provide a camera with high sensitivity even if an output to the outside is weak. [Solution] This camera includes a light source 3, a demultiplexing unit 5 which demultiplexes light from the light source 3 into first demultiplexed light and second demultiplexed light, a first modulator 7 which modulates the first demultiplexed light to obtain a modulated signal, an emission unit 9 which emits the modulation signal modulated by the first modulator 7, and a phase imparting means 11 which imparts a plurality of types of phase shifts to the second demultiplexed light to obtain phase-imparted local light.

Abstract: To provide a method and device capable of easily measuring the CMRR vs. frequency characteristics of an optical receiver. Light having a measurement frequency (? [hz]) is split into two different paths, and a first optical two-tone signal, which is signal light and has a frequency difference (???? [hz]), and a second optical two-tone signal, which is local light and has a frequency difference (?+?? [hz]), are obtained and input into a coherent receiver to be measured, wherein electrical signals output from the receiver are measured to obtain both the ratio of the intensity of a signal component having the frequency ???? [hz] to the intensity of a signal component having the frequency ? [hz], which corresponds to the CMRR on the signal light side, and the ratio of the intensity of a signal component having the frequency ?+?? [hz] to the intensity of the signal component having the frequency ? [hz], which corresponds to the CMRR on the local light side.

Abstract: To provide a method and device capable of easily measuring the CMRR vs. frequency characteristics of an optical receiver. Light having a measurement frequency (? [hz]) is split into two different paths, and a first optical two-tone signal, which is signal light and has a frequency difference (???? [hz]), and a second optical two-tone signal, which is local light and has a frequency difference (?-?? [hz]), are obtained and input into a coherent receiver to be measured, wherein electrical signals output from the receiver are measured to obtain both the ratio of the intensity of a signal component having the frequency ???? [hz] to the intensity of a signal component having the frequency ? [hz], which corresponds to the CMRR on the signal light side, and the ratio of the intensity of a signal component having the frequency ?+?? [hz] to the intensity of the signal component having the frequency ? [hz], which corresponds to the CMRR on the local light side.

Abstract: Disclosed is an optical control type phased array antenna apparatus having an array antenna of antenna elements. An optical signal processor optically processes input high-frequency signals, and outputs optically processed signals including signal components having phases corresponding to directions in which radio wave signals come and having frequencies equal to those of the input high-frequency signals. Then, each frequency converter mixes a received signal with the optically processed signal in correspondence with the antenna element, and outputs a frequency-converted signal having a frequency of a difference between a frequency of the received signal and a frequency of the optically processed signal. Further, a combiner combines the frequency-converted signals.

Abstract: A method and system of transformer protection in which parallel admittance currents indicative of the apparent excitation state of a transformer to be protected are evaluated from the transformer terminal voltages and currents sampled at a proper interval, and discrimination between an internal defect and excitation inrush is made in response to a magnitude of the parallel admittance current, and a breaker opening command is issued in response to a judgement of internal defect. The method and system enables high-accuracy and high-sensitivity fault detection through a simple computation.

Abstract: In a transformer protection system, data of voltages and currents detected at individual terminals of a transformer connected to an electric power system are supplied to a computer. The computer computes driving point admittances or shunt admittances of the transformer on the basis of the voltage and current data and predetermined transfer admittances of the transformer and decides that an internal fault has occurred in the transformer when the values of the driving point admittances or shunt admittances deviate from pre-set reference values, thereby disconnecting the transformer from the electric power system.