ch8_part1_baseband

ch8_part1_baseband - EEN 404 Communication Systems Ch8 Part...

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1 EEN 404 EEN 404 Communication Systems Communication Systems Ch8 Part I Ch8 Part I Baseband Baseband Data Transmission Data Transmission
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2 Receiver Transmitter Digital data transmission system
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3 Noise effect on baseband digital communications (CH8.1) Figure 8-2 System model and waveforms for synchronous baseband digital data transmission. (a) Baseband digital data communication system. (b) Typical transmitted sequence. (c) Received sequence plus noise.
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4 Gaussian process with zero mean and psd N 0 /2 during one symbol period s(t) = A, t [t 0 , t 0 +T) Objective: decide whether the transmitted symbol is A or –A from y(t) Integrate-and-dump detector Q1: How well does this receiver perform? Q2: on what parameters does its performance depend? Probability of error
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5 Output of the integrator: Synchronization is assumed : starting and ending times of each pulse are known by the receiver where Since n(t) is a Gaussian r.p. with zero mean, and integrator is a linear operation, N is a Gaussian r.v.
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6 What is the pdf of N ? N N (0,N 0 T/2)
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7 If A is sent, and N < -AT, then V<0 If - A is sent, and N > AT, then V>0 Two kinds of errors (wrong decision)
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8
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9 The average error probability: Because P(A)+P(-A)=1, and P(E|A)=P(E|-A) , we have Thus, the important parameter for performance is A 2 T/N 0 Two ways to explain A 2 T/N 0 : First: the energy of each symbol is : an often-used reference as SNR in the digital comm.
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This note was uploaded on 10/28/2010 for the course EEN 404 taught by Professor X.cai during the Spring '10 term at University of Miami.

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ch8_part1_baseband - EEN 404 Communication Systems Ch8 Part...

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