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ECE 4371, Fall, 2010 Introduction to Telecommunication Engineering/Telecommunication Laboratory PowerPoint PPT Presentation


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ECE 4371, Fall, 2010 Introduction to Telecommunication Engineering/Telecommunication Laboratory. Zhu Han Department of Electrical and Computer Engineering Class 5 Sep. 7 th , 2010. Overview. Financial Aid Opportunity: 3 REU Some materials are not according to book PLL AM broadcasting.

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ECE 4371, Fall, 2010 Introduction to Telecommunication Engineering/Telecommunication Laboratory

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Ece 4371 fall 2010 introduction to telecommunication engineering telecommunication laboratory l.jpg

ECE 4371, Fall, 2010Introduction to Telecommunication Engineering/Telecommunication Laboratory

Zhu Han

Department of Electrical and Computer Engineering

Class 5

Sep. 7th, 2010


Overview l.jpg

Overview

  • Financial Aid Opportunity: 3 REU

  • Some materials are not according to book

  • PLL

  • AM broadcasting.

  • TV, analog. (digital will be studied later)

  • Midterm 1, 10/5: analog only


Review l.jpg

Review


Type of waves l.jpg

Type of waves


Radio frequency bands l.jpg

Radio Frequency Bands


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Satellite Communications

  • Large communication area. Any two places within the coverage of radio transmission by satellite can communicate with each other.  

  • Seldom effected by land disaster ( high reliability)

  • Circuit can be started upon establishing earth station (prompt circuit starting)

  • Can be received at many places simultaneously, and realize broadcast, multi-access communication economically( feature of multi-access)

  • Very flexible circuit installment , can disperse over-centralized traffic at any time.

  • One channel can be used in different directions or areas (multi-access connecting).


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Rain Attenuation


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Carrier Recover Error

  • DSB: e(t)=2m(t)cos(wct)cos((wc+ w)t+)

    e(t)=m(t) cos((w)t+)

    • Phase error: if fixed, attenuation. If not, shortwave radio

    • Frequency error: catastrophic beating effect

  • SSB, only frequency changes, f<30Hz.

    • Donald Duck Effect

  • Crystal oscillator, atoms oscillator, GPS, …

  • Pilot: a signal, usually a single frequency, transmitted over a communications system for supervisory, control, equalization, continuity, synchronization, or reference purposes.


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Phase-Locked Loop

  • Can be a whole course. The most important part of receiver.

  • Definition: a closed-loop feedback control system that generates and outputs a signal in relation to the frequency and phase of an input ("reference") signal

  • A phase-locked loop circuit responds both to the frequency and phase of the input signals, automatically raising or lowering the frequency of a controlled oscillator until it is matched to the reference in both frequency and phase.


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Voltage Controlled Oscillator (VCO)

  • W(t)=wc+ce0(t), where wc is the free-running frequency

  • Example


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Ideal Model

  • Model

    • Si=Acos(wct+1(t)), Sv=Avcos(wct+c(t))

    • Sp=0.5AAv[sin(2wct+1+c)+sin(1-c)]

    • So=0.5AAvsin(1-c)=AAv(1-c)

  • Capture Range and Lock Range

LPF

VCO


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Carrier Acquisition in DSB-SC

  • Signal Squaring method

  • Costas Loop

  • SSB-SC not working


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Costas receiver


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PLL Applications

  • Clock recovery: no pilot

  • Deskewing: circuit design

  • Clock generation: Direct Digital Synthesis

  • Spread spectrum:

  • Jitter Noise Reduction

  • Clock distribution


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Block diagram of FDM system.


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Illustrating the modulation steps in an FDM system


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FMA of SSB for Telephone Systems


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FMA of SSB for Telephone Systems


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FMA of SSB for Telephone Systems


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AM Broadcasting

  • History

  • Frequency

    • Long wave: 153-270kHz

    • Medium wave: 520-1,710kHz, AM radio

    • Short wave: 2,300-26,100kHz, long distance, SSB, VOA

  • Limitation

    • Susceptibility to atmospheric interference

    • Lower-fidelity sound, news and talk radio

    • Better at night, ionosphere.


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Superheterodyne vs. homodyne

  • Move all frequencies of different channels to one medium freq.

    • In AM receivers, that frequency is 455 kHz,

    • for FM receivers, it is usually 10.7 MHz.

    • Filter Design Concern

    • Accommodate more radio stations

    • Edwin Howard Armstrong


Television l.jpg

Television

Digital Display (CRT)

Analog Display (TV)

Eliminate flicker effects


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Deflection Signal and Synchronization

Deflection signal and synchronization signal

525525 30=8.27M


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Solar Power and Human Eye


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RGB, LIQ

mL=0.3mr+0.59mg+0.11mb

mI=0.6mr+0.28mg-0.32mb

mQ=0.21mr-0.52mg+0.31mb


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Bandwidth

VSB and QAM


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Comb Filtering


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NTSC, PAL, and SECAM

  • National Television System Committee

    • Low complexity, higher vertical color resolution

    • 525 line/60Hz(30frames per second)

  • Phase Alternative Line: PAL

    • The phase of the color components is reversed from line to line

    • Robust to Multipath, phase distortion

    • 625line/50Hz(25 frames per second), slightly larger bandwidth

  • SECAM

    • Requires the receiver to memorize the content of each line

  • Mono when used for different standards


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TV standards in the world


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Why is it Changing for Digital TV?

  • No snow, no static, no ghosts

  • Higher resolution images, and Sound

  • Additional channels

  • Frees up Bandwidth for Other Important Needs

  • More Options

    • Improved captions (but not without pain)

    • Interactive TV

    • TV to your Cell Phone or PDA? (Iphone, Asia)

Digital is Better


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Resolution

Clearer and More Detailed

ATSC

ATSC


Digital tv l.jpg

Digital TV

Displays as Pixels

  • Signal is just a bunch of bits

  • Define color and intensity of each point on the screen

  • Bit stream is heavily compressed

  • Captions are also digital

And That’s the News, Tonight

1010011000101101110100110001011011


Connector overview l.jpg

Connector Overview

  • Coaxial Cable

  • Composite

  • S-Video

  • Component

  • HDMI

Common Connectors

From Cable, Satellite or Antenna to set top box or TV

Yellow is video + Red and White for Audio

Carries Video with improved Quality

Red, Blue, Green (RGB) is Video, + Red and White for Audio

Digital quality and does captions

Newest, Best all digital Video and audio,

but doesn’t do encoded captions


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Summary

  • Feb 17, 2009: Analog Broadcasts Stop

  • Digital TVs Should be Fine

    • High Definition Video and Audio

    • Some Requirements to Get Captions

      • Learn where captions will be decoded

      • Learn how to control

      • Use the right connectors

    • More Options for Captions

      • Color

      • Font size and style

      • Opacity

  • Analog TVs Will Still Work With Digital/Analog Converter

    • Cable and Satellite Subscribers (May have to trade in STB)

    • Cable and Satellite Subscribers may still want a D/A Converter for emergencies

    • Must Buy Converter Box To View Over The Air Signal on Analog TV

      • Wait until you know what you need

      • Don’t wait until the coupons are gone

      • Only have 90 days after you receive coupon

  • Expect Problems and Learning Curve on Captions

Be Prepared

Check out the features and convenience of

TVs, STBs, converters, cables etc.

Some can be very inconvenient.


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