ece 4371 fall 2010 introduction to telecommunication engineering telecommunication laboratory l.
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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

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

Zhu Han

Department of Electrical and Computer Engineering

Class 5

Sep. 7th, 2010

overview
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
satellite communications
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).
carrier recover error
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.
phase locked loop
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.
voltage controlled oscillator vco
Voltage Controlled Oscillator (VCO)
  • W(t)=wc+ce0(t), where wc is the free-running frequency
  • Example
ideal model
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

carrier acquisition in dsb sc
Carrier Acquisition in DSB-SC
  • Signal Squaring method
  • Costas Loop
  • SSB-SC not working
pll applications
PLL Applications
  • Clock recovery: no pilot
  • Deskewing: circuit design
  • Clock generation: Direct Digital Synthesis
  • Spread spectrum:
  • Jitter Noise Reduction
  • Clock distribution
am broadcasting
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.
superheterodyne vs homodyne
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
Television

Digital Display (CRT)

Analog Display (TV)

Eliminate flicker effects

deflection signal and synchronization
Deflection Signal and Synchronization

Deflection signal and synchronization signal

525525 30=8.27M

rgb liq
RGB, LIQ

mL=0.3mr+0.59mg+0.11mb

mI=0.6mr+0.28mg-0.32mb

mQ=0.21mr-0.52mg+0.31mb

bandwidth
Bandwidth

VSB and QAM

ntsc pal and secam
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
why is it changing for digital tv
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

resolution
Resolution

Clearer and More Detailed

ATSC

ATSC

digital tv
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
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

summary
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.