need someone to do work on optical communications

ITT 655-01 OPTICAL COMMUNICATIONS I ANALYSIS ASSIGNMENT 5 PROBLEMS 1. An optical communications link is to be built using fiber rated for 5000 MHz-km. The light source is a laser diode producing 0.25 mW. The fiber has losses of 0.4 dB/km and is available in 2 km lengths. It can be spliced with a loss of 0.2 dB per splice, and there will be a 5 dB loss in the connectors throughout the system. The receiver used has a sensitivity of -30 dBm. The source rise time is 2 ns, and the receiver rise time is 4 ns. a) Prepare a loss budget for a link 20 km long, and calculate the system margin in dB. b) What would be the maximum bandwidth that could be used with the system in (a)? 2. A fiber-optic cable has a rise time of 2 ns/km and a length of 40 km. It is used with a receiver with a rise time of 20 ns and a transmitter with a rise time of 50 ns. Calculate the total rise and bandwidth of the system. 3. Over what distance could a signal be transmitted using the cable in Problem #2 and a data rate of 100 Mb/s with RZ code? Neglect the transmitter and receiver rise times, and consider only the cable. 4. What is the maximum total system rise time that would be acceptable for a 10 Mb/s signal using NRZ code?