Radiometer calibration method

Abstract

The invention discloses a radiometer calibration method. On the basis of completing the absolute calibration of cold and heat sources by a 'four-point non-linear method', the 'relative calibration' process of 'noise calibration' and 'gain calibration' is executed periodically according to different abilities for maintaining stability by each parameter of the radiometer to acquire more accurate characteristic parameters of the radiometer and target observation data. By the method, the calibration and observation accuracy of the radiometer can be improved, the absolute calibration process of the cold and heat sources is not needed to be executed frequently, the requirement on operating environment is reduced greatly, the radiometer can complete periodic automatic calibration, and field application and unattended long-term operation can be realized.

Description

Technical field [0001] The invention relates to a calibration method of a microwave radiometer, and further relates to a data measurement method thereof, that is, calibrating the radiometer and performing target observation to improve the calibration and observation accuracy of the radiometer. Background technique [0002] According to the classic design theory of radiometers, no matter what kind of structure and working frequency of the radiometer, its video output voltage U o And the target brightness temperature T at the antenna port A The relationship between can be approximated by a linear equation: [0003] U o =G S ·(T A +T RN ) (1) [0004] In the above formula: G S Is the system gain of the radiometer, T RN Is the equivalent noise temperature of the system. [0005] The actual application of the radiometer is to measure U o Value to calculate T A , Which requires first determining the system's own characteristic parameter G S And T RN . And sure G S...

AI Technical Summary

Problems solved by technology

[0010] [1] Due to ignoring the actual non-linear factors, there are always errors in the calculation results using linear equations, which cannot meet the high-precision application requirements;

[0011] [2] In engineering practice, the radiometer system gain G S and equivalent noise temperature T RN It is not constant, but fluctuates and drifts over time, that is, the calibration results cannot remain accurate and effective for a long time, so it is necessary to manually perform frequent absolute calibration of cold and heat sources

[0020] Although the "four-point nonlinear method" improves the measurement accuracy of the radiometer, due to the system gain G S and equivalent noise temperature T RN The fluctuation and drift of the radiometer still require frequent absolute calibration of cold and heat sources during the working process of the radiometer, which still cannot meet the actual needs of field operations.

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