Abstract: Provided is an AD converter that is capable of converting a wideband noise signal of several GHz or more into a digital signal and that can be used even when an installation space and power supply are severely limited. The AD converter includes: a comparator (10) configured to compare an input voltage of an analog signal to a determination voltage; an adjustment unit (12) configured to shift at least one of the input voltage of the analog signal or the determination voltage; an encoder (11) configured to output time-series data of one bit based on a result of the comparison obtained by the comparator; a processing unit (13) configured to calculate a frequency of appearance of an output code included in the time-series data; and a control unit (14) configured to cause the adjustment unit to operate so that a result of the calculation obtained by the processing unit becomes a predetermined value.

Abstract: Provided is an AD converter that is capable of converting a wideband noise signal of several GHz or more into a digital signal and that can be used even when an installation space and power supply are severely limited. The AD converter includes: a comparator (10) configured to compare an input voltage of an analog signal to a determination voltage; an adjustment unit (12) configured to shift at least one of the input voltage of the analog signal or the determination voltage; an encoder (11) configured to output time-series data of one bit based on a result of the comparison obtained by the comparator; a processing unit (13) configured to calculate a frequency of appearance of an output code included in the time-series data; and a control unit (14) configured to cause the adjustment unit to operate so that a result of the calculation obtained by the processing unit becomes a predetermined value.

Abstract: Provided is a method of calibrating a microwave radiometer, which eliminates use of liquid nitrogen as a calibration source. The method is applied to a microwave radiometer configured to receive, by a receiver having a primary radiator connected thereto, a radio wave emitted from an object to be measured depending on a temperature of the object to be measured and to measure a brightness temperature of the object to be measured from an output signal of the receiver. In the method, the method a noise temperature Trx of the receiver appearing on an output side of the receiver is calibrated by observing a plurality of calibration sources having known brightness temperatures. The method includes using a radio wave reflector configured to totally reflect noise radiated from an input side of the receiver as one of the plurality of calibration sources.

Abstract: Provided is a method of calibrating a microwave radiometer, which eliminates use of liquid nitrogen as a calibration source. The method is applied to a microwave radiometer configured to receive, by a receiver having a primary radiator connected thereto, a radio wave emitted from an object to be measured depending on a temperature of the object to be measured and to measure a brightness temperature of the object to be measured from an output signal of the receiver. In the method, the method a noise temperature Trx of the receiver appearing on an output side of the receiver is calibrated by observing a plurality of calibration sources having known brightness temperatures. The method includes using a radio wave reflector configured to totally reflect noise radiated from an input side of the receiver as one of the plurality of calibration sources.