13. The total loss in a fiber link is 5.2 dB, the design margin is 0 dB, and the optical budget is 3.3 dB. Is this fiber link compatible with the optical budget? A. Yes. B. Fiber link compatibility isn't dependent on optical budget. C. There's no way to tell until the system is assembled. D. No.

Consider the problem of servo control using PWM signals. Assume we have the following requirements or given conditions. • The repetition period of the PWM pulse for servo control is 20 ms. • The pulse width is between 1.0 to 2.0 ms, with 1.5 ms setting the servos to the center. • We need a resolution of no less than 1 us (micro second) for the pulse width change. • The timer used for the PWM generation has a 16-bit prescaler and a 16- bit counter. • The clock to the prescaler is 10 MHz. Determine the following (which may not be unique): 1. The range of PSC that satisfies the requirements for resolution and period of the pulses.

4. (8 pts) A communication link has a bit rate of 1 Gbps and a length of 40 km. Propagation velocity is 2.5 × 108 m/s. Information frames are 9200 bytes long. The frame header is 100 bytes. One 100-byte ACK frame is sent for every received information frame. (a) What is the minimum window size that maximizes the effective bit rate? (b) What is the information effective bit rate if the window size is 3 frames? (c) What is the information effective bit rate if the window size is 100 frames?

3. (a) Using the following Figure 3, estimate the attenuation (in dB) of a fibre optic cable for the indicated wavelengths and distances in the Table below. (b) The horizontal axis in Figures 1 and 2 represents frequency, while the horizontal axis in Figure 3 represents wavelength. (i) Determine the relationship between wavelength and frequency. (ii) If the propagation speed of light in an optical fibre is 2 x 108 m/s, sketch another representation of Figure 3 using frequency in the horizontal axis. Loss (dB/km) 100 50 10 5 1 0.5 0.1 0.05 0.01 T 800 Distance 1 km 10 km 20 km 1000 1200 1400 Wavelength (nm) L dB at 800 nm 1600 dB at 1200 nm Figure 3 1800