The Satellite Electro-Optic Payload System needs special interest for the limited conditions with the low power consumption and the space environment for solar radiation.
The image sensor system with the CMOS image sensor or the TDI (Time Delayed Integration) CCD (Charge coupled Device) sensor, acquires the high resolution and quality data from the wanted target.
The acquisition image quality should be mainly depend on the GSD (Ground Sampled Distance), SNR (Signal to Noise Ratio), MTF (Modulation Transfer Function).
In this paper, the SNR will be described with all kind noise and noise reduction function from the sensor control to sensor system operation. The satellite camera has so many kinds noise from the image sensor, sensor control board, camera system, payload system, and, S/C Bus.
The high resolution camera with high performance needs the high elaborate control signals, high voltage level, and the high speed control signal. Also, the image sensor has the unique dark signal from the manufacturing process.
The image data has the several noise signals from the various condition including the thermal condition and sensor control system including the outside unit for spacecraft operation.
The light source from the optical module shall be converted to digital number on the ADC (Analog to Digital Converter).
The image data should be compressed because of the massive acquisition image data and efficient transmission to the next image handling unit. During the compression process, the high frequency image data may be lost with high probability.
Before the post correction, the camera system including the video optics and image sensor, which improves the acquisition image quality through the low noise processing with sensor and sensor system.
On the already manufactured sensor level, the noise reduction is impossible, the additive noise from the outside condition, the thermal noise must be reduced by the effective effort by the image sensor control system level.
The outside noise including the thermal noise must be removed on ASP (Analog Signal Processing) using the CDS (Corrective Double Sampling) which the original signal will be removed from the save offset signal. On this process, the pre-pixel and the dark-pixel from the original sensor, will be used.
The non-uniformity correction shall be used with gain, offset, and correction parameter required to obtain optimized image using the various method two or three point correction method.
In addition, image sensor system uses the operation methods which are the integration time control and the image overlapping using the internal memory for reducing the unwanted noise signal.
Also, the image sensor system design requirement is one alternative that shall be proposed previously. The definition of the target signal selection, the sensor system hardware status, and the operation condition are derived the reasonably SNR for image acquisition.
All these effect, the image sensor system in satellite can acquire the high quality image with low noise on orbit.