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ECE 402
Communications Engineering
Quiz 2
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.
•
Two
handwritten
8.5”
×
11” reference sheets 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
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View Full Document Problem 1 (25 pts):
The heights of American women are well modeled as a Gaussian distribution
with a mean of 64” (5’ 4”) and a standard deviation of 3”. What fraction of American women are over
5’ 10” (=70”)?
2
One of two equally likely messages is sent over an AWGN channel with noise
PSD
N
0
/
2 using
pulsewidth modulation (PWM)
, where 0
≤
τ
≤
T
:
0
T
0
( )
x t
D
1
( )
x t
0
T
D
τ
(a)
Find the optimal receiver in its simplest form. In what sense is it optimal?
(b)
Find the biterrorrate of the optimal receiver in terms of
D
,
T
,
τ
and
N
0
. What value of
τ
gives
the best biterrorrate?
3
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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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