Oct. 29, 2012 Hankuk Univ. of Foreign Studies Han Jun Sang

(1)

Dept. of Information & Communication Eng.

Wireless Communications lab.

HUFS.

Hankuk Univ. of Foreign Studies

Digital Communications &

Laboratory

: 6 ^th week,

Pulse Modulation, & Pulse Code Modulation (Part #1 : Sampling)

Oct. 29, 2012 Hankuk Univ. of Foreign Studies Han Jun Sang

1/67

(2)

HUFS.

• Teaching Assistant

Communication Engineering

Jun Sang Han (M.S. Student)

•

Mobile : +82-10-2300-6089

•

E-mail : zereint1101 at nate.com

•

Room : 304-1

•

Wireless Communication Lab (WLCLAB) http://wlclab.hufs.ac.kr

•

Dept. of Information and Communication Engineering, HUFS

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HUFS.

• 1. Introduction

• 2. Sampling : Ideal, & Practical Sampling

• 2. Experiment : Random Variable, & Random Process

• Conclusion

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Review

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Review

• Analog Communication System (Chapt. 4, & 5)

• Modulation

• Amplitude Modulation (AM) (Chapt. 4)

• DSB-SC

• DSB-TC

• SSB

• VSB

• Angle Modulation (Chapt. 5)

• Frequency Modulation (FM)

• Phase Modulation (PM)

• Probability – Random Variable & Random Process (Chapt. 6)

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1. Introduction

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• Typical Digital Communication System

Tx

Rx

1. Introduction

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• Typical Digital Communication System

Analog Data Digital Data ( Sampling, Quantization )

Compression

To Add Redundant Bits For lower bit error

(1) Baseband Modulation : Line Coding (2) Bandpass Modulation : Carrier Modulation

1. Introduction

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• Analog – Digital Conversion (ADC)

1. Introduction

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• Analog to Digital Conversion (ADC)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

-5 -4 -3 -2 -1 0 1 2 3 4 5

time

Amplitude

Analog waveform

1. Introduction

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0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

-5 -4 -3 -2 -1 0 1 2 3 4 5

time

Amplitude

Discrete time

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

-5 -4 -3 -2 -1 0 1 2 3 4 5

time

Amplitude

Digital symbol

Sampling Quantization

• Analog to Digital Conversion (ADC)

1. Introduction

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2. Sampling

: Ideal, & Practical Sampling

2. Sampling : Ideal, & Practical Sampling

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• 2.1. Ideal Sampling

• Impulse Sampling

• Sampling Theorem

• 2.2. Practical Sampling and PAM

• Natural Sampling

• Flat-top Sampling

2. Sampling : Ideal, & Practical Sampling

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2.1. Ideal Sampling

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• Sampling Theorem

2.1. Ideal Sampling

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• Impulse Sampling

2.1. Ideal Sampling

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• Impulse Sampling

2.1. Ideal Sampling

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• Impulse Sampling

2.1. Ideal Sampling

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• Impulse Sampling

2.1. Ideal Sampling

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• Impulse Sampling

2.1. Ideal Sampling

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• Impulse Sampling

2.1. Ideal Sampling

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• Signal Reconstruction

• Ideal Reconstruction Filter

• Practical Reconstruction Filter

• Zero – order hold circuit

• First – order hold circuit

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

-0.5 0 0.5 1 1.5

time [sec]

x(t)

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

-0.5 0 0.5 1 1.5

time [sec]

x_s(t)

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

-0.5 0 0.5 1 1.5

time [sec]

x^- (t)

( )

x t ^Sampling x t _s ( ) Reconstruction x t ˆ( )

2.1. Ideal Sampling

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• Ideal Reconstruction Filter

2.1. Ideal Sampling

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• Ideal Reconstruction Filter

2.1. Ideal Sampling

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• Ideal Interpolation

2.1. Ideal Sampling

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• Ideal Interpolation

2.1. Ideal Sampling

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• Practical Reconstruction Filter

• Zero – order hold circuit

• First – order hold circuit

2.1. Ideal Sampling

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• Practical Reconstruction Filter: Zero-order hold circuit

2.1. Ideal Sampling

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• Practical Reconstruction Filter: Zero-order hold circuit

2.1. Ideal Sampling

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• Practical Reconstruction Filter: First-order hold circuit

2.1. Ideal Sampling

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• Practical Reconstruction Filter: First-order hold circuit

2.1. Ideal Sampling

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2.2. Practical Sampling

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• Practical Problem

2.2. Practical Sampling

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• Practical Problem

2.2. Practical Sampling

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• Practical Problem

2.2. Practical Sampling

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• Ideal (Impulse) & Practical Sampling

2.2. Practical Sampling

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• Practical Sampling: Natural Sampling

2.2. Practical Sampling

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• Practical Sampling: Natural Sampling

2.2. Practical Sampling

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• Practical Sampling: Natural Sampling

2.2. Practical Sampling

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• Practical Sampling: Natural Sampling

2.2. Practical Sampling

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• Practical Sampling: Natural Sampling

2.2. Practical Sampling

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• Practical Sampling: Natural Sampling

2.2. Practical Sampling

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• Practical Sampling: Flat-top Sampling

2.2. Practical Sampling

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• Practical Sampling: Flat-top Sampling

2.2. Practical Sampling

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• Practical Sampling: Flat-top Sampling

2.2. Practical Sampling

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• Practical Sampling: Flat-top Sampling

2.2. Practical Sampling

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• Practical Sampling: Flat-top Sampling

2.2. Practical Sampling

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3. Experiment

: Aliasing, & Practical Sampling

3. Experiment : Aliasing, & Practical Sampling

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• Example #1 : Aliasing Effect

3. Experiment : Aliasing, & Practical Sampling

• 다음의 신호를 생성하라.

 

( ) sinc 100

2

x t  t

• Sampling Frequency를 400, 300, 200, 150 Hz로 변화시키면서 진폭 스펙트럼을 확인하라.

• Nyquist rate를 만족하는 최저 주파수를 계산하고, 시뮬레이션 결과와 비교하라.

-0.050 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0.05 0.5

1 1.5

time [sec]

Original Signal x(t)

-5000 -400 -300 -200 -100 0 100 200 300 400 500

0.002 0.004 0.006 0.008 0.01 0.012 0.014

frequency [Hz]

Spectrum of Original Signal x(t)

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• Example #1 : Aliasing Effect

3. Experiment : Aliasing, & Practical Sampling

-0.050 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0.05 0.5

1 1.5

time [sec]

Aliasing Effect, Sampling Rrequency = 400Hz

-5000 -400 -300 -200 -100 0 100 200 300 400 500

0.002 0.004 0.006 0.008 0.01 0.012 0.014

frequency [Hz]

•

Result : Sampling Frequency = 400 Hz

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HUFS.

• Example #1 : Aliasing Effect

3. Experiment : Aliasing, & Practical Sampling

-0.050 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0.05 0.5

1 1.5

time [sec]

-5000 -400 -300 -200 -100 0 100 200 300 400 500

0.002 0.004 0.006 0.008 0.01 0.012 0.014

frequency [Hz]

•

Result : Sampling Frequency = 300 Hz

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HUFS.

• Example #1 : Aliasing Effect

3. Experiment : Aliasing, & Practical Sampling

-0.050 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0.05 0.5

1 1.5

time [sec]

-5000 -400 -300 -200 -100 0 100 200 300 400 500

0.002 0.004 0.006 0.008 0.01 0.012 0.014

frequency [Hz]

•

Result : Sampling Frequency = 200 Hz

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• Example #1 : Aliasing Effect

3. Experiment : Aliasing, & Practical Sampling

-5000 -400 -300 -200 -100 0 100 200 300 400 500

0.002 0.004 0.006 0.008 0.01 0.012 0.014

frequency [Hz]

-0.050 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0.05 0.5

1 1.5

time [sec]

•

Result : Sampling Frequency = 150 Hz

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• Example #1 : Aliasing Effect

3. Experiment : Aliasing, & Practical Sampling

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Signal Generation

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• Example #1 : Aliasing Effect

3. Experiment : Aliasing, & Practical Sampling

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Sampling Frequency for Aliasing Effect

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• Assignment #1 : Aliasing Effect

3. Experiment : Random Variable, & Random Process

• 와 를 이용하여 Example #1의 과정을 수행하고 결과를 비교 분석하라.

1

( )   50

x t   t

 

2

( ) 100

x t   t

1

( )

x t x t

₂

( )

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• Assignment #2 : Signal Reconstruction

3. Experiment : Random Variable, & Random Process

• 0차 보간법과 1차 보간법을 사용하여 Example #1의 샘플링한 신호를 재구성하고 결과를 비교 분석.

• 시간 영역과 주파수 영역에서 각각 수행하라.

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

-0.5 0 0.5 1 1.5

time [sec]

x(t)

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

-0.5 0 0.5 1 1.5

time [sec]

x_s(t)

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

-0.5 0 0.5 1 1.5

time [sec]

x^- (t)

( )

x t ^Sampling x t _s ( ) Reconstruction x t ˆ( )

• Practical Reconstruction Filter

• Zero – order hold circuit

• First – order hold circuit

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• Example #2 : Practical Sampling – Natural, & Flat-top

3. Experiment : Aliasing, & Practical Sampling

 

( ) sinc

x t  t

• 펄스 폭이 0.04 sec 이고, 샘플링 주기는 0.2 sec로 Natural Sampling과 Flat-top Sampling을 수행.

-4 -3 -2 -1 0 1 2 3 4

-0.5 0 0.5 1 1.5

time [sec]

Original signal x(t)

-5 -4 -3 -2 -1 0 1 2 3 4 5

0 0.2 0.4 0.6 0.8 1

frequency [Hz]

Specturm of Original signal x(t)

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3. Experiment : Aliasing, & Practical Sampling

•

Result : Natural Sampling

• Example #2 : Practical Sampling – Natural, & Flat-top

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

-0.5 0 0.5 1 1.5

time [sec]

Practical Sampling : Natural Sampling

-25 -20 -15 -10 -5 0 5 10 15 20 25

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

frequency [Hz]

Specturm of Natural Sampling

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3. Experiment : Aliasing, & Practical Sampling

•

Result : Flat-top Sampling

• Example #2 : Practical Sampling – Natural, & Flat-top

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2

-0.5 0 0.5 1 1.5

time [sec]

Practical Sampling : Flat-top Sampling

-25 -20 -15 -10 -5 0 5 10 15 20 25

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

frequency [Hz]

Specturm of Flat-top Sampling

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3. Experiment : Aliasing, & Practical Sampling

• Example #2 : Practical Sampling – Natural, & Flat-top

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3. Experiment : Aliasing, & Practical Sampling

• Example #2 : Practical Sampling – Natural, & Flat-top

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This part used to show only a graph !!

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3. Experiment : Aliasing, & Practical Sampling

• Example #2 : Practical Sampling – Natural, & Flat-top

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• Assignment #3 : Practical Sampling – Natural, & Flat-top

3. Experiment : Random Variable, & Random Process

• Example #2의 예제 코드를 분석하라.

( 아래 부분을 중점적으로 분석)

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Conclusion

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Conclusion

• Summary

• Pulse Modulation, & Pulse Code Modulation : Part #1, Sampling

• Next week

• Pulse Modulation, & Pulse Code Modulation

: Part #2, Quantization, & Pulse Code Modulation

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Oct. 29, 2012 Hankuk Univ. of Foreign Studies Han Jun Sang

Digital Communications &

Laboratory

: 6 th week,

Pulse Modulation, & Pulse Code Modulation (Part #1 : Sampling)

Oct. 29, 2012 Hankuk Univ. of Foreign Studies Han Jun Sang

1/67

• Teaching Assistant

Communication Engineering

Jun Sang Han (M.S. Student)

Mobile : +82-10-2300-6089

E-mail : zereint1101 at nate.com

Room : 304-1

Wireless Communication Lab (WLCLAB) http://wlclab.hufs.ac.kr

Dept. of Information and Communication Engineering, HUFS

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Contents

• 1. Introduction

• 2. Sampling : Ideal, & Practical Sampling

• 2. Experiment : Random Variable, & Random Process

• Conclusion

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Review

Review

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Review

• Analog Communication System (Chapt. 4, & 5)

• Modulation

• Amplitude Modulation (AM) (Chapt. 4)

• DSB-SC

• DSB-TC

• SSB

• VSB

• Angle Modulation (Chapt. 5)

• Frequency Modulation (FM)

• Phase Modulation (PM)

• Probability – Random Variable & Random Process (Chapt. 6)

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1. Introduction

1. Introduction

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• Typical Digital Communication System

Tx

Rx

1. Introduction

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• Typical Digital Communication System

1. Introduction

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• Analog – Digital Conversion (ADC)

1. Introduction

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• Analog to Digital Conversion (ADC)

1. Introduction

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Sampling Quantization

• Analog to Digital Conversion (ADC)

1. Introduction

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2. Sampling

: Ideal, & Practical Sampling

2. Sampling : Ideal, & Practical Sampling

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• 2.1. Ideal Sampling

• Impulse Sampling

• Sampling Theorem

• 2.2. Practical Sampling and PAM

• Natural Sampling

• Flat-top Sampling

2. Sampling : Ideal, & Practical Sampling

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2.1. Ideal Sampling

2.1. Ideal Sampling

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• Sampling Theorem

2.1. Ideal Sampling

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• Impulse Sampling

2.1. Ideal Sampling

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: 6 ^th week,

x t ^Sampling x t _s ( ) Reconstruction x t ˆ( )