Patent ID: 6729756
Filing Date: 2004-05-04
Classification: G01K

Abstract:
A method for calibrating a total-power microwave radiometer having a cold calibration source and a hot calibration source and measuring brightness temperature, the method comprises the steps of:measuring the brightness temperature of the hot calibration source having a temperature of Thot1 under conditions where the ambient temperature is constant; measuring the brightness temperature of the hot calibration source having a temperature of Thot2 under conditions where the ambient temperature is constant, where Thot1 and Thot2 are different temperatures; measuring the brightness temperature of the cold calibration source where the ambient temperature is constant; repeating a predetermined number of times at least one of said steps of measuring the brightness temperature of the hot calibration source having a temperature of Thot1, measuring the brightness temperature of the hot calibration source having a temperature of Thot2, and measuring the brightness temperature of the cold calibration source; calculating the standard deviation &Dgr;Thot1 from the measured brightness temperatures of said hot calibration source having a temperature of Thot1; calculating the standard deviation &Dgr;Thot2 from the measured brightness temperatures of said hot calibration source having a temperature of Thot2; calculating the standard deviation &Dgr;Tcold from the measured brightness temperatures of said cold calibration source; and calibrating the total-power microwave radiometer by defining the brightness temperature of the cold calibration source according to the following equation: Tcold[(&Dgr;Thot1âˆ’&Dgr;Tcold)Thot2âˆ’(&Dgr;Thot2âˆ’&Dgr;Tcold)Thot1]/(&Dgr;Thot1âˆ’&Dgr;Thot2).