Part $2.$ Upgrade possibilities.

$7.$ The network is to be upgraded to $40$ Gbit$/$s still using only one wavelength. Which of the following statements is generally INCORRECT?

a$)$ The upgraded system can use either EDFAs or the same $10$Gbit$/$s electronic regenerators

b$)$ The upgraded system can only use EDFAs

c$)$ The customer receiver may not work properly

d$)$ The overall network may not even work at $10$ Gbit$/$s due to dispersion effects

$8.$ The network is to be upgraded to $40$ Gbit$/$s by using four wavelengths around the $1550$nm region multiplexed together. Which of the following statements is generally CORRECT?

a$)$ The fibre loss will increase by $20$ dB

b$)$ Only an optical amplifier can amplify the four wavelengths together

c$)10$ laser transmitters are needed at the hub

d$)$ Only two customer receivers are needed

$9.$ The network is to be upgraded to $100$ Gbit$/$s by using ten wavelengths around the $1550$nm region multiplexed together. Which of the following statements is generally CORRECT?

a$)$ The fibre loss will increase by $30$ dB

b$)$ An electronic regenerator is the best choice

c$)$ The system will not be affected by dispersion problems

d$)$ There will be small extra losses due to the wavelength filtering components