Gain internal calibration method and system for on-orbit receiver of satellite-borne microwave radiometer

Abstract

The invention discloses a gain internal calibration method and system for an on-orbit receiver of a satellite-borne microwave radiometer, and belongs to the technical field of space microwave remote sensing. The method comprises the following steps: in a ground test stage of the satellite-borne microwave radiometer, carrying out two-point calibration by adopting an external cold calibration sourceand a matching load installed in a receiver to obtain the noise temperature of the receiver, and obtaining the temperature sensitivity of the noise temperature of the receiver by changing the physical temperature of the receiver; and after the satellite-borne microwave radiometer works on orbit, periodically switching and matching a load end through a receiver switch, and calculating the gain ofthe receiver by combining the noise temperature and temperature sensitivity of the receiver obtained by the ground test, so as to complete the calibration of the gain of the receiver. By overcoming the limitation of an existing method, the gain of the on-orbit rear receiver of the radiometer can be accurately, simply and conveniently calibrated in real time, and the gain internal calibration method for the satellite-borne microwave radiometer receiver is practical.

Description

technical field [0001] The invention relates to an on-orbit receiver gain internal calibration method and system for a spaceborne microwave radiometer, which belongs to the technical field of space microwave remote sensing. Background technique [0002] Traditional space-borne microwave radiometers generally use two-point calibration on the antenna surface to calibrate the gain of the receiver. The high-temperature source generally uses a black-body heat source, and the low-temperature source is realized by reflecting the cold-air signal through a cold-air mirror. , the rotating antenna can periodically observe the heat source and the cold air reflector for two-point calibration to ensure the measurement accuracy of the system. With the application of the synthetic aperture microwave radiometer, because it uses an array antenna, it is impossible to calibrate the receiver at two points in the form of a heat source and a cold air mirror like a traditional radiometer, so it is ...

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Problems solved by technology

[0007] The radiometer observes the cold space through satellite maneuvering, or the cold space is observed through the cold space reflector combined with the normal temperature signal injected by the matching load noise to perform two-point calibration on the receiver to obtain gain. This method either requires the satellite to perform attitude maneuvering, so that The calibration cycle is generally too long to perform real-time calibration; or adding a cold-air antenna will greatly increase the complexity of the system, especially for the synthetic aperture radiometer, adding a cold-air antenna is difficult to effectively implement in engineering

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