Elektronik Öğretmenliği

EBB 333 Haberleşme Sistemleri-I

2012-2013 Güz Yarıyılı

Öğretim Üyesi

Prof. Dr. Yunus E. Erdemli

Ofis: 1011, Tel: 303-2238

E-posta: yunusee@kocaeli.edu.tr

Arş. Gör. Mustafa H. B. Uçar

Ders Programı

Pz.tesi: 12:00 15:00 (Teo)

15:00 16:50 (Lab)

Referanslar:

1) Modern Digital & Analog Communication Systems

B. P. Lathi, Oxford University Press, 1998

2) Analog Haberleşme

A. H. Kayran, E. Panayırcı, Ü. Aygölü; Birsen Yayın, İstanbul

http://www.birsenyayin.com

3) Analog ve Sayısal İletişim

H. P. Hsu (Çeviri: E. Afacan) Schaum’s Outline Series, McGraw-Hill

Nobel Yayın Dağıtım, Ankara 2003 www.nobelyayin.com

4) http://www.clee.freehomepage.com/teaching.html

Değerlendirme: Dönem İçi Notu = Ara Sınav (%25) + Laboratuar (%15)

Dönem Sonu Notu = Final Sınavı (%60)

Haberleşme Sistemlerinde Temel Kavramlar

Matematiksel Temeller İşaret ve Sistemlerin Sınıflandırılması

Fourier Dönüşümü ve Özellikleri

Sinyallerin Doğrusal ve Doğrusal Olmayan Haberleşme Kanallarında İletimi

Modülasyon Çeşitleri Genlik Modülasyonu (AM)

Açı Modülasyonu (FM/PM)

Ders İçeriği

Telekomünikasyon Trafiği Gelişimi

Haberleşme

Servislerindeki

Artış

Electronic Communications: Telephone, wireless phone, TV, radar, etc.

Concept and Model of Communications

General Communication Model

Source Transmitter Transmission

System Receiver Destination

Microphone Telephone Computer Scanner

Transformer Encoder Compress Modulator

Line/Cable Fiber/Air Satellite Network

Transformer Decoder Uncompress Demodulator

Speaker Earphone Computer Printer

Basic Communication Criteria: Performance, Reliability, Security

Signal Frequency, Spectrum & Bandwidth

Signal in time domain Signal in frequency domain Spectrum

cos(2πf1t)

t

s(t)

T period

T=1/f1

f: frequency f

S(f)

f1

s(t)=Acos(2πf1t) + Bcos(2πf2t) f

S(f)

f1

A

f2

B

t

s(t)

Analog Signal

t

s(t)

Digital Signal S(f)=ʃs(t)e-j2πftdt

Fourier Transform f

S(f)

f

S(f)

Bandwidth

Bandwidth

Periodic

Aperiodic

• Earthquake wave: 0.01 ~ 10 Hz

• Nuclear explosion signal: 0.01 ~ 10 Hz

• Electrocardiogram (ECG): 0 ~ 100 Hz

• Wind noise: 100 ~ 1000 Hz

• Speech: 100 ~ 4000 Hz (4 KHz)

• Audio: 20 ~ 20000 Hz (20 KHz)

• NTSC TV: 6 MHz

• HDTV: > 10 MHz

Time-Frequency Relation & Signal Bandwidth

General Relations: Time Domain Frequency Domain Signal Bandwidth

Change Slow Low Frequency Small

Change Fast High Frequency Large

t

s1(t)

t

s2(t) BW1 < BW2

?

System Frequency Response & Bandwidth

System: H() Input Signal x(t) Output Signal y(t) =H[x(t)]

Input Spectrum: X(f) Output Spectrum: Y(f)

System Frequency Response: H(f) = Y(f)/X(f)

f

H(f)

System Bandwidth

Signal can pass

Signal can’t pass

Important Reasons for Modulation:

• Ease of Radiation: c= f

• Simultaneous Transmission of Several Signals

FDM/TDM

• Effecting the Exchange of SNR with B

Channel Capacity Channel Bandwidth

Signal-to-Noise Ratio: S_

N

Modulation

Carrier: Acos(2πfct+φ) where fc is called carrier frequency

Modulation: change or modify values of A, fc, φ according to input signal m(t) - modify A A[m(t)]: Amplitude Modulation (AM)

- modify fc fc[m(t)]: Frequency Modulation (FM) - modify φ φ[m(t)]: Phase Modulation (PM)

Modulator m(t)

Acos(2πfct+φ)

modulated signal: s(t)

Amplitude Modulation (AM)

Frequency Modulation (FM) Frequency Modulation (FM)

rms value: 2/CPg

rms value:

2

DC) (constant, )(

CP

Ctg

g

rms value: C

-

Lowpass signals

g(t)

G(w)

y(t)

Y(w)

h(t)

H(w) LTI

krad/sn 203

229,203min0

w

Ideal High-Pass Filter Frequency Response

Ideal Band-Pass Filter Frequency Response

Physically Realizable Filter

g(t)

G(w)

y(t)

Y(w)

h(t)

H(w) LTI

SIGNAL DISTORTION OVER A COMMUNICATION CHANNEL

Partial Power Contribution

Summary

.

USB (upper sideband)

LSB (lower sideband)

DSB: LSB+USB

(double sideband)

LPF

DSB spectrum

E(w)

+

Diode-Bridge

Electronic Switch

Series-Bridge Diode Modulator

Shunt-Bridge Diode Modulator

Ring Modulator

Switching Demodulator:

LPF

t = |m(t)min| Modulation Index:

A=1

DC blockage

Upper limit for RC:

t t

i

q = 0 for i=1 & q = -p/2 for i=2

cos(wct)

LPF

DSB-SC BPF

USB

&

DC blockage

m(t)

below.

.

V s

LPF

k

Instantaneous Frequency:

F

5102fk

MHz 100cf

10pk

MHz 100cf

5102fk

MHz 100cf

frequency-shift keying

(FSK)

2/pk

MHz 100cf

phase-shift keying

(PSK)

1)(tmk p

NBPM Modulator

NBFM Modulator

Bandwidth

bandwidth of baseband signal m(t)

Wide-Band FM (WBFM) or Wide-Band PM (WBPM)

Narrow-Band FM (NBFM) or Narrow-Band PM (NBPM)

102 5

fk

2

2

102 5

fk

102 5

fk4

7.5

maximum:

Features of Angle Modulation

In AM, the transmission bandwidth (BT) cannot be changed. Therefore, AM systems

do not have the feature of exchanging signal power for BT.

However, in angle modulation, BT can be adjusted by adjusting f. Also, for angle

modulated systems, SNR (BT)2.

f . .

.

-

.

For AM:

m(t)

2

2