Abstract
A digital-correlation full-polarized microwave radiometer is an important passive remote sensor, as it can obtain the amplitude and phase information of an electromagnetic wave at the same time. It is widely used in the measurement of sea surface wind speed and direction. Its configuration is complicated, so the error analysis of the instrument is often difficult. This paper presents a full-polarized radiometer system model that can be used to analyze various errors, which include input signal models and a full-polarized radiometer (receiver) model. The input signal models are generated by WGN (white Gaussian noise), and the full-polarized radiometer model consists of an RF front-end model and digital back-end model. The calibration matrix is obtained by solving the overdetermined equations, and the output voltage is converted into Stokes brightness temperature through the calibration matrix. Then, we use the four Stokes parameters to analyze the sensitivity, linearity, and calibration residuals, from which the simulation model is validated. Finally, two examples of error analysis, including gain imbalance and quantization error, are given through a simulation model. In general, the simulation model proposed in this paper has good accuracy and can play an important role in the error analysis and pre-development of the fully polarized radiometer.
Highlights
A full-polarized microwave radiometer is a type of passive microwave remote sensor developed in the mid-1990s, represented by the WindSat spaceborne polarimetric microwave radiometer [1,2] and the Water Cycle Observation Mission (WCOM) in China [3,4]
The theoretical brightness temperature of the system can be calculated by Equations (2) and (3), and the simulated brightness temperature can be calculated by the simulation model using the calibration matrix
This paper presented a simulation model of a full-polarized radiometer system
Summary
A full-polarized microwave radiometer is a type of passive microwave remote sensor developed in the mid-1990s, represented by the WindSat spaceborne polarimetric microwave radiometer [1,2] and the Water Cycle Observation Mission (WCOM) in China [3,4] It is based on the traditional microwave radiometer to measure the first two Stokes parameters of the target radiation, further increasing the ability to measure the third and fourth. A system simulation model based on digital signal processing was presented for a total power radiometer, which was used to estimate the output dynamic range, linearity, and sensitivity [17]. The input signals are used as input to the full-polarized radiometer model to generate output voltages of four Stokes parameters, which include hot and cold calibration target signals, ideal full-polarized signals, as well as CPCT signals.
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