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Unformatted text preview: ECE 402 Communications Engineering Quiz 1 Fall 2009 TEST NAME: STUDENT NUMBER: INSTRUCTIONS • Write your name and student number in the space provided above. • This quiz is closed book and closed notes. • One handwritten 8.5” × 11” reference sheet may be used (both sides). • Conventional calculators may be used (but no computers, PDAs or other wireless devices) • Give stepbystep solutions that include all details. Assume the graders know only the basics. • Box your final answer . GRADES 1 2 3 4 Total 1 Problem 1 (25 pts): A signal is digitally recorded using sampling and uniform quantization. Assuming the highest frequency tone to be recorded is 8,000 Hz, what is the minimum sampling rate that can be used? How many bits would be required to store one minute of this signal at a signal toquantization noise ratio of at least 80 dB? Assume that the signal is peaklimited to  x ( t )  ≤ 1 V and has normalized power P x = 0 . 25 W. 2 Problem 2 (25 pts): Find the Fourier Transform of x ( t ) = 1 1 + t 2 . 3 Problem 3 (25 pts): The joint pdf of two random variables X and Y is f X,Y ( x,y ) = { 3 x 4 y 2 , y ≥ 1 ,x ≥ 1 , otherwise (a) Find the marginal pdf of X ....
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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.
 Fall '08
 Townsend

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