Real-time low-cost passive imaging system for automotive applications

This paper presents the construction of a real-time low-cost radiometric system working around 94 GHz for the safety of people in automotive transportation. This camera will realize 25 images per second and will be able to see several hundred meters in bad weather conditions. We have chosen to use an adding noise radiometer with low energy consumption. Four important points are discussed. First, the radiometric visibility gives the investigation volume for different weather conditions. The computation of such volumes shows a real interest for the radiometric technique. Secondly, a new calibration method, based on a modulated noise diode source, followed by a real-time Kalman filter processing is validated on a 4 GHz radiometer. Thirdly the image processing, based on a deconvolution process and followed by a regularization of the temperature improves the spatial resolution and optimizes the radiometer matrix located in the focal plane of a Fresnel lens. Finally the millimeter-wave radiometer in the 51-55 GHz band is described. We present also the low-noise amplifier (LNA) that will be used in the final project of the camera system working in the 94 GHz band