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Unformatted text preview: ECE 562 Fall 2011 November 9, 2011 SOLUTIONS TO HOMEWORK ASSIGNMENT 5 1. Differential Detector and Noncoherent Orthogonal Modulation. Show that for binary DPSK, the non coherent detector based on the twosymbol interval statistic Y n is the same as the differential detector (see notes). Ans: The noncoherent detector is ˆ m n ( Y n ) = arg max m =1 , 2 h Y n , ˜ s m i with ˜ s 1 = √ E 1 1 , ˜ s 2 = √ E 1 1 Thus ˆ m n ( Y n ) = 1 if  R n + R n 1  ≥  R n R n 1  2 otherwise = 1 if Re[ R n R ? n 1 ] ≥ 2 otherwise 2. To track or not to track the phase. Consider a BPSK system with an imperfect phase reference, and a BDPSK system with differential detection. Assume that the data rates, transmit powers, and noise PSD’s for the two systems are the same. Let P b (BSPK ,φ ) and P b (BDPSK) denote the respective bit error rates for communication. Find the value of phase error φ for which P b (BSPK ,φ ) = P b (BDPSK) = 10 6 ....
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 Fall '09
 Pulse shaping, Quadrature amplitude modulation, Raisedcosine filter, V.V. Veeravalli

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