Signal-to-Noise Ratio (SNR) requirement of Space Solar Telescope is 10

4

.At the limits of CCD full well electron numbers

in order to improve SNR

the images collected by CCD must be accumulated in pre-processing unit;CCD image correcting technique was adopted to decrease CCD self-noise;In order to solve image drift

images correlative interpolation accumulation method was brought forward to further improve SNR and to meet design requirement.Pre-processing unit also undertakes tasks as following:Stokes parameter calculation during polarization measurement

CCD control

focusing control and image formatting.The requirements of pre-processing unit were analyzed

and system design solution was established.A ground functional prototype was completed according to above scheme with DSP and FPGA as the

main chips

and system software was developed.The system function was simulated and testing under ground support equipment.