Papers by Keyword: Microwave Radiometer

Abstract: Passive microwave remote sensing is one of the most effective methods for inversing soil moisture. Under the condition of laboratory, firstly, C band microwave radiation was used to achieve the trial of ground-based remote sensing soil moisture, and then regression analysis was carried out according to the data measured, finally, got the C band experience regression model of soil moisture inversion. The results showed that: in the level-off state of soil surface, soil humidity and soil microwave emission rate is linear negative correlation, in the other words, soil microwave emission rate decreased while the soil moisture increased. Besides, with the increasing of soil surface roughness, both the value of microwave polarization index (MPDI) and microwave emission rate polarization difference Δe have the same trend of quick drop, stabilization and slow raise, and it presented the relationship of quadratic curve with the change of roughness.

Abstract: Under unfavorable wheather conditions, such as mist, dew and drizzle, contamination flashover may occur on polluted insulators. According to the properties of radiation, this paper proposes a new method for detecting the pollutant on insulators by the dual-channel Dicke radiometer based on the pollutants radiation characteristic and the theory of component emissivity. This study fully considered the effect that the radiation energy of multiple scattering and the external environment on antenna temperature, and it described by the structure of antenna temperature with matrix. A new dual-channel Dicke radiometer has been developed to measure the radiation characteristics of insulators. With a large number of data obtained by experiments, the relationship between ESDD/NSDD and the antenna temperature was researched. And it proposed an empirical formula to calculation ESDD and NSDD. This study provides a new method of detecting insulator contamination by microwave radiometer.

Abstract: Insulator contamination threatens grid safety. And insulator pollution detection can prevent accident occurrence. An invented insulator pollution detector based on microwave radiation is introduced in the paper. The result of testing on-site high-voltage insulator pollution with the detector compared with ESDD and NSDD. And the comparison results indicate the insulator pollution detector can test high-voltage insulator pollution.

Abstract: Based on the microwave radiometer for goals positioning the least-square method to basically have two kinds: using linear approximation, but positioning accuracy is lower; Or by using nonlinear approximate such as Newton iterative method, but need to consider iterative convergence and computation problem. Based on this situation, a new data fusion approach is given. This method for taking two vessels measurement use linear least squares to the fair, then introduced one kind of weighting operation to carry on the fusion to two vessels rendezvous result, get multiple-vessel localization model and the error analysis. The simulation result indicate that the new algorithm increase the localization precision, enhance the positioning stability.

Abstract: This paper introduces a calibration device for microwave (millimeter and submillimeter) radiometer. The device can provide the microwave radiometer continuously variable linearly polarized noise temperature. The paper also introduces a real-time calibration method to achieve the microwave radiometer calibration, and the test of microwave radiometer sensitivity and linearity.