Abstract: Output value signals from radiometer or receiver channels are normalized to achieve a flat field response when creating a millimeter wave image. A normalizing factor is applied to the output value signals from each channel, and the normalizing factor accommodates drift in offset of the output value signals on a scan-by-scan basis. The normalizing factor is based on each channel observing a different mean scan brightness temperature from a portion of the scene than the mean brightness temperature of the entire scene. The normalizing factor is obtained by solving a system of simultaneous equations in which normalizing factors from all of the channels are related to one another, preferably by a consistency condition where the mean scan temperature of each channel is equal to an average of the intensities of those image pixels to which the output value signals from that channel contributes.

Abstract: Scene-independent baseline signals in output value signals from radiometer or receiver channels used in millimeter wave imaging are eliminated or reduced and an improved image is composed. The scene-independent baseline signals are believed to result from a standing wave which is established between an antenna of the channel and a movable scanning element which scans radiant energy from the scene into each channel. The movable scanning element introduces changes in geometry which change the characteristics of the baseline signals depending upon the position of the movable scanning element. The baseline signals are measured by viewing a scene of uniform brightness temperature, and the baseline signal contribution is subtracted from the output value signals from each channel. The baseline compensated output signals are used to compose an image with better contrast.

Abstract: Output value signals from radiometer or receiver channels are normalized to achieve a flat field response when creating a millimeter wave image. A normalizing factor is applied to the output value signals from each channel, and the normalizing factor accommodates drift in offset of the output value signals on a scan-by-scan basis. The normalizing factor is based on each channel observing a different mean scan brightness temperature from a portion of the scene than the mean brightness temperature of the entire scene. The normalizing factor is obtained by solving a system of simultaneous equations in which normalizing factors from all of the channels are related to one another, preferably by a consistency condition where the mean scan temperature of each channel is equal to an average of the intensities of those image pixels to which the output value signals from that channel contributes.