Question 6 (30 Marks) - DSB-LC Amplitude modulation A double-sideband large carrier (DSB-LC) amplitude modulated carrier
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Question 6 (30 Marks) - DSB-LC Amplitude modulation A double-sideband large carrier (DSB-LC) amplitude modulated carrier
Question 6 (30 Marks) - DSB-LC Amplitude modulation A double-sideband large carrier (DSB-LC) amplitude modulated carrier signal o(t) with additive Gaussian noise n(t) is fed through a bandpass filter H(w) (as illustrated below) $(t) vo(t) Σ H (w) n (t) The DSB-LC signal is modelled by o(t) = [f(t) + A] cos(wet) where f(t) = k cos(wmt + 0) is a sinusoidal modulating signal of frequency wm rad/sec and phase 0. A is the carrier amplitude and we is the carrier frequency in rad/sec. The power spectral density of the noise is S(w) = n/2 Watts/Hz. The filter transfer function is H(w) = Crect (2) + Crect(), where B is the filter bandwidth in hertz and C is a constant. The bandwidth 2πB = 4wm. a) Derive an expression for power spectral density S(w) at the output (both signal and noise) of the filter, and plot Suo (w), labelling significant information. (15 marks)