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大家帮我算一道题谢谢

2010/4/18镜像同步1 回复

You are required to design an optical communication system to meet specified requirements for a terrestrial link. The transmitter, optical fibre and receiver are to be specified as well as the number and type of repeaters (regenerators). Specifications; Data rate: 100Mb/s Bit error rate: 1x10-9 Distance between OLTE: 500km Operating wavelength: 1.55um The following components are available to implement the design. Optical transmitter; DFB laser Risetime = falltime = 2ns Typical optical output power = -3dBm Laser spectral width = 0.3nm Optical fibre; single mode fibre attenuation = 0.4dB/km dispersion = 20ps/nm.km Optical receiver 1; PIN photodiode Risetime = falltime = 1ns Dark current = 0A Responsivitty = 0.8 A/W Optical receiver 2; APD photodiode Risetime = falltime = 1ns Dark current = 0A Responsivitty = 1 A/W Noise factor = Gx and x = 1 Assume the noise bandwidth of the receiver is B / 2 and that the thermal front end noise variance = 1.7 x 10 -16 A2. i) Initially assume that a receiver sensitivity of 1500 photons/bit can be achieved, the fiber is in 3km sections, each splice is 0.1dB loss and the connectors have 2dB loss. The system margin is required to be 6dB. Hence determine the maximum length between repeaters arising from the loss limit. ii) Calculate the dispersion limit and the corresponding maximum length of fibre. iii) Specify the limiting factor that determines the maximum distance between repeaters, and specify repeater length and the BER requirement for each repeater section. iv) Consider the PIN and APD receivers, find their sensitivities, do they meet system requirements? If not suggest how the subsystem components may be modified to meet the transmission specification. v) Discuss your design and whether or not you have met the system design spec. Suggest two enhancements to increase system performance.

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大家帮我算一道题 谢谢

大家帮我算一道题谢谢