Simulation of actively polarimetric calibration source based on correlated noise signals by Simulink

Abstract

Fully polarimetric microwave radiometer can receive both the two orthogonal polarization components and their complex correlation components, which are defined as the third and fourth Stokes parameters, of the signals radiated from the detected target. In order to achieve the precisely quantitative remote sensing of fully polarimetric radiometer, an accurate calibration is necessary. For this purpose, a uniformly stable and accurate calibration source which is performed as the calibration standard is of vital importance. The traditional and commonly used blackbody calibration target can't radiate signals with polarized components. So it is significant to design an active calibration source to generate noise signals with full polarized components for fully polarimetric microwave radiometer calibration. With the full investigation into the pre-existing polarimetric calibration sources and their characteristics, this paper design a miniature and portable actively polarmetric calibration source. First of all, the design principles of the calibration source of fully polarized microwave radiometer based on correlated noise signals are elaborated. Secondly, MATLAB/Simulink is used to establish the simulation model of the calibration source. The reference signals generation module generates the original reference signals with full polarized components which can be controlled by program language. The original reference signals are converted to the signals with the designed frequency by the frequency modulation module. The noise voltage control module outputs the noise signals with different voltages which covered all the counts needed for polarimetric radiometer calibration within the voltage counts of cold and hot target. Finally, the power spectrum of each module of the simulation model is given. The results show a great consistency between the theoretical and simulated results. Thus, the feasibility of the designed calibration source for fully polarimetric microwave radiometer based on the program language controlled correlated noise signals is verified. Therefore, the functional block diagram of the real circuits of this calibration source based on the simulation is designed for the practical application.