Abstract
Electro-Optical design of a push-broom space camera for a Low Earth Orbit (LEO) remote sensing satellite is performed
based on the noise analysis of TDI sensors for very high GSDs and low light level missions. It is well demonstrated that
the CCD TDI mode of operation provides increased photosensitivity relative to a linear CCD array, without the sacrifice
of spatial resolution. However, for satellite imaging, in order to utilize the advantages which the TDI mode of operation
offers, attention should be given to the parameters which affect the image quality of TDI sensors such as jitters,
vibrations, noises and etc. A predefined TDI stages may not properly satisfy image quality requirement of the satellite
camera. Furthermore, in order to use the whole dynamic range of the sensor, imager must be capable to set the TDI
stages in every shots based on the affecting parameters. This paper deals with the optimal estimation and setting the
stages based on tradeoffs among MTF, noises and SNR. On-board SNR estimation is simulated using the atmosphere
analysis based on the MODTRAN algorithm in PcModWin software. According to the noises models, we have proposed
a formulation to estimate TDI stages in such a way to satisfy the system SNR requirement. On the other hand, MTF
requirement must be satisfy in the same manner. A proper combination of both parameters will guaranty the full dynamic
range usage along with the high SNR and image quality.
