Papers by Keyword: FSO

Abstract: QC-LDPC can bring a higher coding gain to the FSO system, but the complexity of the decoding algorithm restricted its application in high-speed FSO system.In this paper, it adopts an improved Modified Min-sum Algorithm (MMSA) to reduce the decoding complexity and save decoding time. In this paper, the author programs the decoder with VHDL Hardware Description Language and analyzes the static time of the design with Synplify Pro and QuartusII to verify the correctness. Moreover, each functional unit is downloaded to the EP3C16Q240C8 chip produced by ALTERA Company and encapsulated into the IP core. Finally, we used MATLAB software to build the FSO system for testing decoder performance. The results show that the QC-LDPC decoder based on FPGA has higher reliability in FSO system.

Abstract: Free Space Optics (FSO) communication is a technology widely used today. It involves transmission of data from a transmitter to a receiver. In order to achieve successful data transmission, a continuous alignment between the transmitter and receiver telescope is needed. If not, misalignment will happen due to certain factors. Vibration at the transmitter or the receiver is one of the factors that contribute to misalignment. In this work, active vibration isolation (AVI) system is designed and fabricated in order to improve the performance of the transmitter and receiver in an FSO link. First, a virtual prototype is designed. Then a real prototype is fabricated to implement AVI. The result after applying a controller to the AVI system shows 33.1% reduction in amplitude of displacement of the top plate, in other words reduction in amplitude of vibration.

Abstract: Free-space optics (FSO) communication is a technology that uses light to transmit data through free space. The most important part in FSO communication is the alignment between transmitter and telescope’s receiver. However, since the transmission medium of FSO is atmosphere, it will give misalignment between the transceivers. Hence, auto tracking system is required to solve the problem between the transmitter and receivers. The 3-RPS parallel manipulator has been designed as an auto tracking system for the alignment between transceivers. First, a prototype of the system is designed in SolidWorks and integrated with LabVIEW software to perform virtual prototyping. Then, the result of virtual prrotyping is discussed.

Abstract: In Free Space Optic (FSO) communication, the alignment between transmitter and receiver telescope is very important. The line of sight of their optics must be aligned during the entire communication time; this is crutial in large distance data transmission. One of the factors that causes misalignment is vibration, either at the transmitter or the receiver. In this work, active vibration isolation (AVI) system is designed and developed to tackle this issue. An AVI system isolates FSO devices from direct disturbances or ground vibrations. The LQR controller is proposed and implimented with LabVIEW. A mathematical model of the isolator is derived and the prototype model of the AVI system is designed in SolidWorks. This prototype model is integrated with LabVIEW software to perform virtual prototyping.