Research On Frame Transfer CCD Data Acquisition For Planetary Elliptical Orbit

In recent decades,imaging spectrometer is a newly development technology in remote sensing.It is a technology that combine imaging technology and spectrometer technology.So it can acquire multi-dimension information from target.It is usually used to detect atmosphere,mineral,water on planet.It was widely used in history of human space exploration.Space exploration requires instrument with high sensitivity,high signal-to-noise ratio(SNR)and high coverage rate.Great changes have taken place in detecting technology in many countries.The specificity of the orbits of planetary exploration satellites is generally an elliptical orbit,which is different from the traditional spatial imaging spectral load design.Then make the whole planet map by image stitching.Based on the acquisition process of CCD detector for Mars surface,whose spectrum range is visible and nearinfrared,this paper gave a solution which can meet the system index.According to the introduction of CCD pixel binning and variable frame frequency,the instrument can meet the requirement of high signal-to-noise ratio and applying to Mars orbiter ellipse orbit.This paper show the details structure of CCD47-20,from E2 V,work principle and noise from each process.Non-binning,2x1-horizontal analog,1x2-vertical digital and 2x2 quadratic binning mode was designed because pixel binning can improve the SNR.The increment of SNR is 1.63 times,1.37 times and 2.03 times respectively for three binning mode in our experiment.The experiment result is agree with the theoretical analysis and prove that analysis is correct.This method has been actually applied to engineering projects.Mainly,the CCD driving circuit is introduced of the complete visible near-infrared information link electronic system.What is also introduced is that pre-amplifier protect system from noise and that correlated double sampling(CDS)is for decreasing the KTC noise.Experiment was set up to sample the noise under the dark environment.The root mean square noise keep in a low level and the circuit hardware have great characteristic.The difference of circle and ellipse orbit was shown in the paper.Variable frame frequency has more advantage on ellipse orbit satellite.The calculate result from Mars orbit parameter determine the frame frequency 9-33 fps and the solution of combination fixed frame frequency and variable frame frequency can meet the requirement.The response of system is in good agreement to the same brightness target under the mode of same charging time and variable frame frequency mode.The variance of DN is small enough,which ensure the high stability of design scheme system and achieves good results.All of the above design and verification work was actually applied to the first Mars exploration Mars Mineralogical Spectrometer load electronics design.