Electronic Communication Systems 2nd Edition by Roy Blake

Exercise 44

A laser diode emits a power of 1 mW. It is to be used in a fiber-optic system with a receiver that requires a power of at least 1 W for the required bit error rate. Determine whether the system will work over a 10 km distance. Assume that it will be necessary to have a splice every 2 km of cable. The losses in the system are as follows:
Coupling and connector losses, transmitter to cable: 10 dB
Cable loss: 0.5 dB per km
Splice loss: 0.2 dB per splice
Connector loss between cable and receiver: 2 dB