Question

b) The figure below shows an FM demodulator. s'(t)Envelope detector Demodulated signal s(t) Differentiator Figure 4: Question 2(b) In the system above, the differentiator performs the time-differentiation operation s'(t) = as(t). Also, the envelope detector is assumed to be ideal, capable of extracting the envelope of the incoming signal perfectly. Describe, by equations, how the above FM demodulator may exactly recover the message signal from the FM signal. (6%) (c) Is the FM demodulator in Question 2(b) a coherent detector, or a noncoherent detector? (2%) (d) Consider an FDM system where FM is used for each subband. The system settings are as follows: The bandwidth of all message signals is 3 kHz. The frequency deviation is limited to Af-12 kHz. The total transmission bandwidth of the FDM system is 0.96 MHz. What is the largest possible number of message signals the FDM system (7%) Give a brief explanatiorn can accommodate? You may apply Carson's rule.

Answer 1

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Date.... 10h ナm rig Ban Bu