| Free-Space Optics (FSO), namely Optical Wireless Communication, is a promising technology through transmitting laser signals in the free space to realilze the bi-direction communication of voice, image and data between point-to-point, point-to-mulitipoint and multipoint-to-multipoint. FSO has high bandwidth, no frenquency admission, low cost, strong anti-jamming, good transmission secrecy, simple installation. These merits make FSO as a popular option for mobile communication interconnecting, multi-user LAN extending, temporary data transmitting and out-space communication. Because of the fast development of laser components in the end of 90's, FSO has become a useful technology for broadband access application, and its speed has already reached to 2.5Gbps. FSO has a good transmitting effect in the distance less than 1km. In this dissertation, introduce simply the specialties of Free-Space Optics, application area and product actuality, and discuss that the atmospheric channel has a great influence for FSO system. A practical project has been put forward to show VCSEL transmitter circuit, APD receiver circuit, APD bias circuit, PECL interface circuit, CygnalC8051F015 controller, network interfacer, the flow and MSComm program of management software in details. Estimate the key parameters of BER, SNR, sensitivity and dynamic range of FSO receiver in the theory. Observe FSO equipment operation in the real condition and analyse experimental results. Summarize the performance and characteristics of FSO equipment, point out some ways to improve the sensitivity of FSO system and add ATP subsystem, which is the next step to research. |
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