1a) A 1mw laser is injected into a 150 Km fiber optic cable with a loss of 0.22 dB/Km.  The bit rate is 10 Gbps.  The receiver consists of a photo-detector with a power gain of 0.53 and Temperature of 800 degrees Kelvin, following by a Bit Detector with a Temperature of 600 degrees Kelvin.  Compute the P(Bit Error).  Fiber coupling loss is 2 dB.  Fiber de-coupling loss is 1.5 dB.
 1b) If you were to model the photo detector and the bit detector by one box called a detector, what temperature should this box be assigned?

 2) A system has an identical transmitter,  receiver, bit rate, and cable characteristics as in Problem 1, but an EDFA (Power Gain = 25dB, Noise Temperature = 1640 degrees Kelvin) is to be inserted exactly midway between the transmitter and receiver.  How far apart can the transmitter and receiver be placed if the same probability of a bit error is desired as in problem 1 above.

 3) Suppose the system in problem 2 has the EDFA replaced by a regenerative repeater with the transmitter and receiver characteristics as in 1.  Compute the P(Bit Error) for this system.