Abstract: The purpose of this invention is to provide a building change detection device, and the like, that make it possible to easily compare a three-dimensional model of a building corresponding to individual points in time and a model of the building based on reference information. A building change detection device comprises a measurement data acquisition means for acquiring measurement data indicating the results of measurement based on emitted laser light emitted onto a region under measurement including a building and reflected laser light, a building model generation means for using the measurement data to generate a building model that is a three-dimensional point-cloud model of the building, a building reference model acquisition means for acquiring a building reference model, and a display control means for carrying out control for displaying a first image including the building reference model and the building model.

Abstract: In order to suppress any reduction in the reception performance of an optical transceiver, the optical transceiver includes a light source, an optical splitter that splits the output of the light source into a first split light and a second split light, an optical modulation unit that modulates the first split light, a coherent receiver that causes the inputted received light to interfere with the second split light, and a first control unit that controls the split ratio of the optical splitter on the basis of the reception characteristic of the received light received by the coherent receiver.

Abstract: In order to suppress any reduction in the reception performance of an optical transceiver, the optical transceiver includes a light source, an optical splitter that splits the output of the light source into a first split light and a second split light, an optical modulation unit that modulates the first split light, a coherent receiver that causes the inputted received light to interfere with the second split light, and a first control unit that controls the split ratio of the optical splitter on the basis of the reception characteristic of the received light received by the coherent receiver.

Abstract: In order to suppress any reduction in the reception performance of an optical transceiver, the optical transceiver includes a light source, an optical splitter that splits the output of the light source into a first split light and a second split light, an optical modulation unit that modulates the first split light, a coherent receiver that causes the inputted received light to interfere with the second split light, and a first control unit that controls the split ratio of the optical splitter on the basis of the reception characteristic of the received light received by the coherent receiver.

Abstract: In order to suppress any reduction in the reception performance of an optical transceiver, the optical transceiver includes a light source, an optical splitter that splits the output of the light source into a first split light and a second split light, an optical modulation unit that modulates the first split light, a coherent receiver that causes the inputted received light to interfere with the second split light, and a first control unit that controls the split ratio of the optical splitter on the basis of the reception characteristic of the received light received by the coherent receiver.

Abstract: An optical transmitter includes: optical modulation means; bias voltage output means for supplying the optical modulation means with a bias voltage on which a pilot signal is superimposed; pilot signal receiving means; and bias voltage control means. The bias voltage control means includes: training means for determining a control start voltage and a control direction of the bias voltage based on a pilot signal component at first and second bias voltage values; and feedback means for determining an appropriate bias voltage to compensate for a deviation of an operating point of the optical modulation means by analyzing the pilot signal component while adjusting the bias voltage in a stepwise fashion along the control direction from the control start voltage after the control start voltage and the control direction are determined.

Abstract: An optical transmitter includes: optical modulation means; bias voltage output means for supplying the optical modulation means with a bias voltage on which a pilot signal is superimposed; pilot signal receiving means; and bias voltage control means. The bias voltage control means includes: training means for determining a control start voltage and a control direction of the bias voltage based on a pilot signal component at first and second bias voltage values; and feedback means for determining an appropriate bias voltage to compensate for a deviation of an operating point of the optical modulation means by analyzing the pilot signal component while adjusting the bias voltage in a stepwise fashion along the control direction from the control start voltage after the control start voltage and the control direction are determined.

Abstract: An optical transmitter includes: a modulator; an output light monitoring unit; and a control unit. The modulator includes a dividing unit dividing light inputted to the modulator into first and second branch lights; first and second modulation units performing phase modulation for the first and second branch lights, respectively; a rotator which rotates the polarization plane of one of the first and second modulated lights; and a polarization combining unit combining the first and second modulated lights. The output light monitoring unit monitors light intensity of the output of the polarization combining unit. The control unit controls at least one of the first and second modulation units, on the basis of a monitoring result by the output light monitoring unit. The control includes a light intensity control making the light intensity of the first and/or second modulated light smaller than a maximum value of a modulation curve light intensity.

Abstract: A coherent optical receiving apparatus according to the present invention includes a coherent optical receiving unit to receive a whole of an optical multiplexed signal into which an optical signal is multiplexed, a tunable filter, a local oscillation unit, and a control unit. The coherent optical receiving unit, which includes a 90-degree hybrid circuit and an optoelectric conversion device, selectively detects an optical signal, which interferes with a local oscillation light outputted by the local oscillation unit, out of the optical multiplexed signal. The tunable filter, which is arranged in front of the optoelectric conversion device on an optical path on which the optical multiplexed signal flows, has a bandwidth within which a plurality of optical signals are included. The control unit makes a central wavelength of the tunable filter and a wavelength of the local oscillation light be changed together.

Abstract: The PD converts the light into a current signal and supplies the converted a current signal to a TIA and a light intensity measuring unit. The TIA converts the current signal into a voltage signal. The CDR circuit identifies whether the voltage signal is 1 data or 0 data for reproduction. The counter counts the 1 data and 0 data, calculates their ratio. The control unit refers to light intensity data from the light intensity measuring unit and a ROM, acquires an optimum ratio, and determines whether the ratio supplied from the counter is the optimum ratio. When the ratio is not the optimum one, the control unit controls the threshold voltage setting unit to set the threshold voltage so that the ratio is the optimum one.

Abstract: The PD converts the light into a current signal and supplies the converted a current signal to a TIA and a light intensity measuring unit. The TIA converts the current signal into a voltage signal. The CDR circuit identifies whether the voltage signal is 1 data or 0 data for reproduction. The counter counts the 1 data and 0 data, calculates their ratio. The control unit refers to light intensity data from the light intensity measuring unit and a ROM, acquires an optimum ratio, and determines whether the ratio supplied from the counter is the optimum ratio. When the ratio is not the optimum one, the control unit controls the threshold voltage setting unit to set the threshold voltage so that the ratio is the optimum one.