Analysis On The Noise Characteristics Of The Microwave Radiometer Channel And The Influence On Radiation Measurement

Microwave radiometer is commonly used to detect the weak microwave signal, and the noise in the channel of the radiometer is a crucial factor which affects the sensitivity. The channel noise includes the thermal noise which caused by the random thermal moving of the electrons both in the active devices and the passive devices, as well as the shot noise and flicker(1/f) noise which mainly come from the active devices.When investigate the characteristics of the noise in radiometer, this article firstly established the simplified channel model of the microwave radiometer using Simulink simulation platform, and used the traditional and improved Allan variance methods to analyze the noise properties of the output signal, and effectively distinguished the white noise and 1/f noise from the output data. Secondly, the wavelet transform had been used to split the 1/f noise from the output signal, and successfully recover the original useful signal, which verified the feasibility of these two approaches in the noises characteristics analysis and split. Finally the traditional and improved Allan variance methods had been used to analyze the noise properties of the 3mm scanning imaging radiometer and the 8mm IF sampling radiometer in our lab, and further certified the main noises in the microwave radiometer. At the same time, the wavelet transform had been used to split the 1/f noise in the measurements; the results demonstrate that the de-noising measurements can better fit the white noise property. This mean that the above methods can better distinguish and the filter the 1/f noise of the radiometer.