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Unformatted text preview: EE 314 Homework 10 Solution 1 12.11: A certain telephone channel has Hc(W)=10^3 over the signal band. The message signal PSD is Sm(w) = (beta)rect[w/(2*alpha)], with alpha = 8000*pi. The channel noise PSD is Sn(w) = 10^8. If the output SNR at the receiver is required to be at least 30dB, what is the minimum transmitted power required? Calculate the value of beta corresponding to this power. 12.21: For the DSBSC system with a channel noise PSD of Sn(w) = 10^10 and a baseband signal of bandwidth 4kHz, the receiver output SNR is required to be at least 30dB. a) What must the signal power Si received at the receiver input? b) What is the receiver output noise power No? c) What is the minimum transmitted power St if the channel transfer function is Hc(w) = 10^4 over the transmission band? 12.31: For an FM communication system with beta = 2 and white channel noise with PSD Sn(w) = 10^10, the output SNR is found to be 28dB. The baseband signal m(t) is Gaussian and bandlimited to 15kHz, and 3*rho loading is used. The demodulator constant alpha = 10^4. This means that the FM demodulator output is alpha*sig'(t) when the input is Acos[wct + sig(t)]. In the present case, the signal at the demodulator output is alpha*kf*m(t). The output noise is also multiplied by alpha. a) Determine the received signal power Si. b) Determine the output signal power So. c) Determine the output noise power No. 12.33: For a modulating signal m(t) = cos^3(wot), show that PM is superior to FM by a factor of 2.25 from the SNR point of view. Hint: Determine mp' by setting m''(t) = 0. 2 ...
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This note was uploaded on 04/08/2010 for the course EE 314 taught by Professor Agbo during the Spring '10 term at Cal Poly.
 Spring '10
 Agbo

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