HW8S - ECE 402 Communications Engineering Homework 8 Solutions(Fall 2009 1 The carrier frequency should be located in the center of the band at f0

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
ECE 402: Communications Engineering Homework 8 Solutions (Fall 2009) 1. The carrier frequency should be located in the center of the band at f 0 = (820 + 920) / 2 = 870 kHz. If the rolloff is r = 0 . 5, the PSK signal bandwidth is W = 2(1 + r ) W N = 1 . 5 f b . For a channel bandwidth of 100 kHz, the symbol rate that uses the entire band is f b = 66 . 6 kbaud. The data rate is R = kf b where k is the number of bits/pulse. Since we require R = 200 kb/s, the signal constellation should have k = ( R/f b ) = 3 bits/pulse, or M = 2 k = 8 points. Thus, we should use 8-PSK. 2. (a) From the figure Z ( f ) = H c ( f ) X ( f ). Since z ( t ) = x ( t + T/ 4) + x ( t - T/ 4), we have Z ( f ) = F [ x ( t + T/ 4) + x ( t - T/ 4)] = ( e 2 πjfT/ 4 + e - 2 πjfT/ 4 ) X ( f ) = 2cos( πfT/ 2) X ( f ) , so H c ( f ) = Z ( f ) /X ( f ) = 2cos( πfT/ 2). (b) From G ( f ) = F [sinc(2 t/T )] = ( T/ 2)Π( Tf/ 2), the system pulse is P ( f ) = G ( f ) H c ( f ) H r ( f ) = ( T/ 2)Π( Tf/ 2) · 2cos( πfT/ 2) · cos(
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/28/2012 for the course ECE 402 taught by Professor Townsend during the Fall '08 term at N.C. State.

Page1 / 2

HW8S - ECE 402 Communications Engineering Homework 8 Solutions(Fall 2009 1 The carrier frequency should be located in the center of the band at f0

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online