| Communication between space satellites is currently used radio and microwave communications.With the continuous development of space exploration in various countries,especially the need for establishing large capacity and high security intersatellite communications is becoming more and more urgent,Intersatellite laser communication has the advantages of high rate and high confidentiality,so it will have a great application prospect in space communication field in the future.The construction of reliable inter-satellite optical communication link depends on the continuous alignment of the two light communication units,which puts forward harsh requirements for the satellite borne ATP(Acquisition Tracking and Pointing).Because of the great difference between space environment and ground environment,satellite borne ATP technology has become a key technology in space optical communication system with great complexity and difficulty.On the one hand,the image processing platform needs to have high data processing ability in order to achieve capture and stable tracking with high accuracy.On the other hand,Due to the special requirements of the space environment,the electronic system of the load equipment is different from the ground equipment in the aspects of signal integrity,reliability,volume and power consumption,anti-space radiation ability,etc.So the image processing platform used by ground ATP can not be copied.Because of the confidentiality of space engineering technology,there are few hardware design details of image processing platform for other projects in the open literature.Neither the processing ability nor the data architecture can meet the requirements of satellite borne ATP.In this paper,the research and development of the principle prototype of satellite borne image processing platform is carried out under such background,which lays a technical foundation for the development of ATP principle prototype.This paper first analyzes the requirements of the image processing platform and designs the system structure.The image processing system is composed of the imaging system with sensor design as the core and the image processing system with DSP and FPGA as the core.This paper analyzes the tracking effect required by ATP and puts forward the core technical parameters of two subsystems.Based on the complexity of the realization of the technical parameters and the particularity of the space environment,the design requirements of anti-space-radiation,signal integrity and drive design based on HDL are proposed.In order to meet the demand of anti-radiation design of image processing platform circuit in space environment,the methods of anti-total dose effect and anti-single particle effect adopted by other space-borne engineering projects are referred to.On the basis of device selection and metal equivalent shielding for total dose effect,this paper presents an effective three-mode redundant loading method for single particle effect,which makes the system meet the demand of anti-radiation load.The reliability of the system under space radiation environment is improved.In the imaging system,the research idea of the imaging automatic exposure adjustment and image data reconstruction and output system based on FPGA for spaceborne environment is proposed around the CMV300 and CMV2000 detection chips.For the image processing system,this paper presents a high speed data transmission and high performance data processing architecture with DSP TMS320C6678 and FPGA XC7K325 T as the core of data processing and VPX as the data bus.Based on this architecture,intensive data operations are processed in parallel by FPGA,such as the whole frame preprocessing of images;DSP serially processes complex mathematical operations and realizes high performance cooperative processing between DSP and FPGA;through a series of functional circuit design,such as storage circuit,analog image output circuit,image input and output channel circuit,power system,clock system,etc;And platform driven development,such as BIOS boot drive,parallel image transmission protocol,serial image transmission protocol and so on.All of this work together to achieve high speed and reliable transmission and processing of large amounts of data.In addition,this paper designs a kind of general filter image preprocessing IP core,which greatly facilitates the research and optimization of the whole image processing algorithm;In view of the limited bandwidth of space-based data,a control method on FPGA for compressed image IP stream is proposed,which makes maximum use of the transmission bandwidth.In the process of hardware platform design,this paper aims at the problem that the signal integrity mainly depends on the designer's experience in the traditional design method.In this paper,a method of adding signal integrity design into the whole development cycle is adopted,and the signal integrity simulation is carried out in both schematic design and PCB design stage.In the stage of schematic design and PCB design,the signal integrity is simulated and analyzed.According to the simulation results,the principle design and routing can be continuously optimized in this paper,which ensures the signal integrity of the final product,and summarizes a series of signal integrity optimization methods in the work.Finally,a prototype of spaceborne ATP principle is designed and developed based on the above proposed design method,architecture and ideas.By assembling and adjusting with other sub-systems,the prototype of the principle has successfully completed the target acquisition,positioning and tracking experiments in the field,and has achieved good results,which has accumulated valuable experience for the development of spaceborne ATP image processing platform. |
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