Design And Implementation Of The Test System For Optical Communication Coarse Pointing Unit Based On LINUX

To realize space optical communications,the most impotant thing is having a reliable and stable communication link. The laser beam precise alignment is based on the APT (acquisition, pointing and tracking) system, the APT system is divided into coarse pointing and fine pointing unit, which is the key equipment of the whole space optical communication system, In the coarse pointing unit design & debug process, a set of special test equipment is essential.Test system is responsible to send control commands to the coarse pointing to control coarse pointing unit, collecte status information of the coarse pointing unit real-timely, and give advice for coarse pointing unit debugging.This paper describes design ideas and realizing process of the hardware and software of the test system. To obtain a stability and maneuverability system, the system uses three-tier structure(the hardware layer,operating system layer and application layer). Hardware layer is the basis of the whole system, the system is designed around S3C2410 which is based on ARM9, design and realize the RS-232, RS-485 and USB communication interface, 640×480 pixel touch screen and high-speed RAM and FLASH storage space, operating system layer of test system is desined based on embedded Linux 2.6.8, This paper gives the loading process of the kernel and file system, discusses the kernel cutting and transplantation process of the embedded Linux, the production of the Cramfs file system and realize process of the system-driven; software layer of the system is based on the QT cross-platform development environment for embedded design, and the software is on the top-level of the human-computer interaction, using the ideas of dual process, the process 1 is mainly responsible for controlling display of the major interface, data updates, data reception work and other human-computer interaction, process 2 is mainly responsible for communication betwin the coarse pointing unit and the test system, as well as unpacking, packing and other data-processing work.In the final, has carried on the test to the system system on the initialize, pre-target and helical-scanning with the test system, as a result,the test system works properly, can realize to the test function for the coarse pointing unit. Finally, this paper presents the method that using adaptive wavelet denoising to analysis and diagnosis the control error of the coarse pointing unit.the results show that the existence of the jump data, increase the control error of the coarse pointing unit to120μrad, if removed the jump data, the accuracy will be within 30μrad, on this basis, if we filter out the noise signal of encoder, the system will further improve control accuracy.