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

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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  1. ECE 4371, Fall, 2010Introduction to Telecommunication Engineering/Telecommunication Laboratory Zhu Han Department of Electrical and Computer Engineering Class 5 Sep. 7th, 2010

  2. 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

  3. Review

  4. Type of waves

  5. Radio Frequency Bands

  6. 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).

  7. Rain Attenuation

  8. 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.

  9. 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.

  10. Voltage Controlled Oscillator (VCO) • W(t)=wc+ce0(t), where wc is the free-running frequency • Example

  11. 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

  12. Carrier Acquisition in DSB-SC • Signal Squaring method • Costas Loop • SSB-SC not working

  13. Costas receiver

  14. PLL Applications • Clock recovery: no pilot • Deskewing: circuit design • Clock generation: Direct Digital Synthesis • Spread spectrum: • Jitter Noise Reduction • Clock distribution

  15. Block diagram of FDM system.

  16. Illustrating the modulation steps in an FDM system

  17. FMA of SSB for Telephone Systems

  18. FMA of SSB for Telephone Systems

  19. FMA of SSB for Telephone Systems

  20. 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.

  21. 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

  22. Television Digital Display (CRT) Analog Display (TV) Eliminate flicker effects

  23. Deflection Signal and Synchronization Deflection signal and synchronization signal 525525 30=8.27M

  24. Solar Power and Human Eye

  25. RGB, LIQ mL=0.3mr+0.59mg+0.11mb mI=0.6mr+0.28mg-0.32mb mQ=0.21mr-0.52mg+0.31mb

  26. Bandwidth VSB and QAM

  27. Comb Filtering

  28. 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

  29. TV standards in the world

  30. 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

  31. Resolution Clearer and More Detailed ATSC ATSC

  32. 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

  33. 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

  34. 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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