The Design Of TDI-CCD Imaging System Based On FPGA

The high resolution of TDI image sensor is very important for observing the surface.As a special kind of linear array sensor,TDI sensor can get pictures which have high signal to noise ration by repeating exposure for relatively moving object and accumulating signal,the linear array form is achieved by the surface array form.TDI sensor has a high signal to noise,high sensitivity,ect.There are many important applications for TDI sensor,such as in industrial measurement and control,machine vision imaging,spectral and chromatographic detection and analysis,medical imaging and other fields.We research the principle of TDI-CCD,design a TDI-CCD imaging system for ocean observation with FPGA and software,implemented by Gigbit Ethernet,collect opticals signal and measure some parameters such as signal-noise ratio with the TDI-CCD imaging system.This paper includes:1.The working principle and relative technology of the imaging system are described.At first,this paper introduces the principle of CCD from the structure to working process.Next,the TDI-CCD working principle is introduced,and distinguished from linear CCD and array CCD;and then,this paper describes noise in the system of CCD.Finally,Gigbit Ethernet is given.2.We designs the circuit for TDI-CCD imaging system,which has TDI-CCD driver sequence,pixel signal processing and collection,Ethernet transaction,power system and level converting.We use correlated double sample chip from ADI to process the analog signal which TDI-CCD outputs,and convert it to 16 bits digital signal.We also use RTL8211E from Realtek to realize the function of Ethernet,use LDO chips to generate different voltages,and use EL7457 to implement level converted for driving TDI-CCD.Finally,we design 4 floors PCB.3.Verilog HDL is used to designing driving circuit and implement that in Xilinx Spartan6.In the imaging system,TDI-CCD driving sequence,register configuring sequence,correlated double sample sequence and Ethernet transaction sequence is included.And all above sequence is generated by timing manager.4.We also develop PC software for the imaging system.That software can be run in.NET 4.5.1 platform.Some parameters in the driving circuit can be set through the software.The software also can receive the image from FPGA and process data simply.5.The paper tests the voltage,the input and output sequence,the driving level for TDI-CCD,the analog output signal form CCD and so on.The paper verifys the function and measures the signal to noise ratio.The experiment proves that the design for TDI-CCD can work correctly,and we can do deep research for sensors.