On-orbit MTF test method of GEO optical satellite based on random phase sampling of critical linear targets

Abstract

Traditional Low Earth Orbit (LEO) optical satellite remote sensor MTF detection method is not suitable for the optical Earth observation satellites in Geostationary Earth Orbit (GEO) due to their high orbital height. Considering the low Ground Sample Distance (GSD) of the GF-4 satellite optical camera, it is difficult to set up large-size targets, combining features of GEO satellite gaze imaging, This paper presents a method to obtain MTF based on spatial random phase sampling of critical linear targets in multi-frame sequence images. The random change of satellite attitude was used to image the same target area for many times, and the resulting images were registered to the unified coordinate system, and target feature information was extracted. Then the Line Spread Function (LSF) was obtained by fitting the data, and finally the MTF curve was obtained by Fourier transform. The digital simulation analysis of the detection method was carried out, and the MTF detection of GF-4 satellite optical camera in orbit was realized through the actual setting of targets in the inspection field, which fully verified the effectiveness of the method.