base band transmission

8/4/2019 Base Band Transmission

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(4.7))(2

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(4.6))(2

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Since g(t)


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Properties of Matched Filters


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2

Y


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(4.27))(

exp1

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isofpdflconditionaThe

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b

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b

Y

W

/TN

Ay

/TNyf

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dt duutN

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utN

utR

/Ntw

b b


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Figure 4.5 Noise analysis of PCM system. (a) Probabilitydensity function of random variable Yat matched filter output

when 0 is transmitted. (b) Probability density function of Y

when 1 is transmitted.


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+ = 00)(2

10 )exp(

1

/TN/A dzzP


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17Figure 4.6 Probability of error in a PCM receiver.

PCM receiver exhibits an exponential improvement in

with increase ineP 0/NEb


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4.4 Intersymbol Interference (ISI)

ISI arises when the channel is dispersive

Figure 4.7 Baseband binary data transmission system.


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(Polar form)

TX Filter Channel RX Filter


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Zero ISI

ionnormalizatby

,1)0(where =p


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kimkim

kim

==

=

if,0,if,0

Condition for zero ISI


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Ideal Nyquist channel


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Figure 4.8 (a) Ideal magnitude response. (b) Ideal basic pulse shape.


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Figure 4.9 A series of sinc pulses corresponding to the sequence 1011010.


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No margin of error in sampling times

0, =it

Caused by timing error


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Figure 4.10 Responses for different rolloff factors.

(a) Frequency response. (b) Time response.


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4.6 Correlative-level (Partial-response)

(Controlled ISI)Duobinary Signaling

Figure 4.11 Duobinary signaling scheme.


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Figure 4.12 Frequency response of the duobinary conversion filter. (a) Magnitude response. (b)

Phase response.

Figure 4.13 Impulse response of the duobinary conversion filter.


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Figure 4.14 A precoded duobinary scheme; details of the

duobinary coder are given in Figure 4.11.


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Figure 4.15 Detector for recovering original binary sequence from the precoded duobinary coder output.


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s

Figure 4.16 Modified duobinary signaling scheme.

Figure 4.17 Frequency response of the modified duobinary conversion filter. (a)

Magnitude response. (b) Phase response.


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Figure 4.18 Impulse response of the modified duobinary conversion filter.


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-

G li d F f C l ti l l di (PRS)


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Generalized Form of Correlative-level coding (PRS)

Figure 4.19 Generalized correlative coding scheme.


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43Figure 4.20 Output of a quaternary system. (a) Waveform. (b) Representation of

the 4 possible dibits, based on Gray encoding.


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Figure 4.24 (a) Near-end crosstalk (NEXT). (b) Far-end crosstalk (FEXT).

Figure 4.25 Model of twisted-pair channel.


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Figure 3.15 Line codes for the electrical representations of binary data.

(a) Unipolar NRZ signaling. (b) Polar NRZ signaling. (c)Unipolar RZ signaling.

(d) Bipolar RZ signaling. (e) Split-phase or Manchester code.


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Figure 4.18 Impulse response of the modified duobinary conversion filter.

Figure 4.20 Output of a quaternary system. (a) Waveform. (b) Representation of

the 4 possible dibits, based on Gray encoding.


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Figure 4.26 (a) Illustrating the different band allocations for an FDM-based ADSL

system. (b) Block diagram of splitter performing the function of multiplexer or

demultiplexer. Note: both filters in the splitter are bidirectional filters.

(DMT)


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Figure 4.7 Baseband binary data transmission system.


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Figure 4.29 Signal-flow graph representation of the LMS algorithm involving the kth tap weight.


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Figure 4.30 Illustrating the two operating modes of an adaptive equalizer: For the training

mode, the switch is in position 1; and for the tracking mode, it is moved to position 2.


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][][ knxkh

Figure 4.31 Impulse response of a discrete-time channel, depicting the precursors

and postcursors.


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Figure 4.32 Block diagram of decision-feedback equalizer.


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Eye Patterns


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y

Figure 4.33 Interpretation of the eye pattern.


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67Figure 4.34 (a) Eye diagram for noiseless quaternary system. (b) Eye diagram for quaternary system

with SNR = 20 dB. (c) Eye diagram for quaternary system with SNR = 10 dB.


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Figure 4.35 (a) Eye diagram for noiseless band-limited quaternary system:

cutoff frequencyfo = 0.975 Hz. (b) Eye diagram for noiseless band-limitedquaternary system: cutoff frequencyfo = 0.5 Hz.

base band transmission

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