Proc. SPIE. 5284, Wireless Communications and Networks
KEYWORDS: Infrared search and track, Infrared imaging, CMOS sensors, Digital signal processing, Wavelet transforms, Detection and tracking algorithms, Image processing, Field programmable gate arrays, Telecommunications, Free space optics
The paper gives a scheme of the algorithm and the architecture of the information processing system of IR beacon image in the APT system. The CMOS image sensor gets the IR beacon's image in the optical antenna. The FPGA implements the IR image preprocessing and the DSP offers the possibilities of processing large high-resolution images. The wavelet transform is used in the image preprocessing, which can decompose the image in multi-scale to select the different frequency components. The IR beacon's position is detected based on gravity center, and the precision servo system finishes the tracking of the IR beacons. Thus the system can implement the acquisition, pointing, tracking and establish the FSO communication link in real time.
The paper presents a scheme of the miniaturization of APT system and the design of the system based on the investigation of status in quo. It deals with the infrared image of the other terminal's beacon from the Charge Coupled Device (CCD) by the Complex Programmable Logic Device (CPLD). The result of the transaction is delivered to Single Chip Microcomputer (SCM), which controls the micro-servomotor. Subsequently, the precision drive system drives the optical system that uses only one light axis for signal beam and beacon to finish the acquisition, pointing, and tracking of the communication terminals. The anlayses of the APT system's error indicate that the tracking error limits in 70uRad with the weight of the system lighter than 8-kilogram.