20.a. A –0.5 dBm signal is transmitted through a fiber link. The transceiver at the receiving end has a  receiver sensitivity threshold of –13 dBm. What's the optical budget in this link? A. 13.5 dB B. 6 dB C. 12.5 dB D. 13 dB 20.b. A transceiver has an extinction ratio of 6 in a fiber link. What's the extinction ratio power penalty? A. 1.5 dB B. 7.8 dB C. 1.1 dB D. 6 dB

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2. What is the frequency swing of an FM broadcast transmitter when modulated 60%?

Q6. Figure Q6 shows the line spectrum of a modulated signal (all components are positive and real). 3 1 232 234 236 238 frequency/kHz Figure Q6: Line spectrum of a modulated signal (a) Describe the modulation scheme. (b) What are the values of the carrier frequency, modulation frequency and the modulation index? (c) What is the transmission efficiency (ratio of modulated to total power) in this example? (d) The reception of this signal is undertaken with a superheterodyne detector using an intermediate frequency of 110 kHz. What is the appropriate local oscillator frequency? (e) Demodulation of this type of signal is usually accomplished using an envelope detector. Describe the principles of operation of an envelope detector and sketch an example circuit. (f) What considerations should be made about the component values in the design of an envelope detector in order to demodulate the signal after shifting to the intermediate frequency? Relative unitsS