Abstract:

In view of the requirement for target radiometric characterization and the problems of the dual channel noise adding radiometer like the complicated video signal processing circuits, and the lack of quantitative analysis for the stable observation time, an improved W-band radiometer is proposed for radiometric characterization. A video signal processing approach based on the direct digital acquisition is employed to reduce the complexity and strengthen the flexibility of the system. The object brightness temperature measurement equation is established and the system theoretical sensitivity is derived by combining the short periodic calibration technique and Allan variance analysis. Also the stable observation time is determined by the stability evaluation of the system. The experimental results show that the sensitivity of a designed radiometer is 0.3 K with an integration time of 1 s, the available stable observation time is able to reach to 40 s and the difference between the measurement and theoretical calculation of the sky brightness temperature is less than 2.6 K within a zenith angle range of 0°~70°. The overall performances of the proposed system are superior to that of the dual channel noise adding radiometer.