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Hdtv technology


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Hdtv technology

  1. 1. HDTVTechnology
  2. 2. Outline •Introduction •HD-History •Architecture•Characteristics of HD standard •Difference b/w HD & Analog •Future of HD •Summary •Conclusion •Refrences
  3. 3. WHY HDTo Overcome Limitations of Analog Television• Noise free pictures• Higher resolution images Widescreen / HDTV• No Ghosting• Enhanced Sound Services• Other Data services. 3
  4. 4. High Definition TelevisionDEFINITION: HDTV is generally recognized as a digitalvideo broadcast with a minimum resolution of 1280pixels wide and 720 pixels high, a rate of 30 or moreframes/second and usually an aspect ratio of 16:9. 4
  5. 5. HDTV History• Early 1980’s: – Japan created analog HDTV• Mid-1980s: – US, trying to stay competitive, decided to go digital – Congress gave stations a separate channel for transition to digital broadcast with the goal of all stations using digital broadcasts by 2006.
  6. 6. Currently...• Less than 15% of US homes have HDTV capabilities• Approximately 21% of stations have digital broadcasts
  7. 7. High Definition TelevisionA standard definition analog television uses acathode ray tube with an electron gun to guidethe path of an electron beam to “paint” 480vertical lines across the face of the screen. Eachtime the beam strikes a dot of phosphor, light isproduced. For a color television set, each spotconsists of a group of three phosphor elements;one for each primary color. 7
  8. 8. HOW HD WORK 8
  9. 9. Implementation - Display technologies• Plasma – Like LCD monitors, plasma HDTV sets are thin and are made up of cells that correspond to pixels sandwiched between glass plates. Plasma cells contain three separate gas-fill sub-cells, one for each color. When a current is applied to a sub-cell, it ionizes the gas emitting ultraviolet light. The ultraviolet light in turn excites fluorescent substances in the sub-cells that emit red, blue or green light.• DLP – Digital light processing is a technology used in projection displays. In DLP monitors, light is reflected off an array of microscopic hinged mirrors. Each tiny mirror corresponds to a visible pixel. The light is channeled through a lens onto the surface of the screen. Single chip DLP projectors can display 16.7 million colors. 3- chip projectors can display 35 trillion colors.• LCoS – Similar to DLP, LCoS projection systems use liquid crystals instead of mirrors to block light. The liquid crystals are arranged in a grid in front of a highly reflective surface.
  10. 10. Motion BlurA sequence of images such of a movie oranimation
  11. 11. HD TV Screen Refresh Rates•A rate of 24 frames/second (progressive) hasbeen the movie film standard since the mid-20’s•The television industry has used a rate of 60frames/second (interlaced) since the 40’s•Newer HDTV’s are being marketed as 120 Hzand 240 Hz using circuitry to help reduce motionblur 11
  12. 12. Technical Aspects Interlaced display
  13. 13. Frame rate conversion - 3-2 pulldown
  14. 14. What is a format? Formats are described by:Number Number Scanning Picture Frame rateof active pixels of active lines mode aspect ratioper line per frame Current main standards are: SMPTE 274 M SMPTE 296 M 14
  15. 15. Archiving High definitionHigh definition video Standard definition video1980 pixels 1080 lines 720 pixels 576 lines 1- hour programme file size : 1- hour programme file size :from374 GB to 673 GB* 72 GB To archive HD, Compression could be required. 15
  16. 16. HDTV & SDTV Comparison• Judging simply on pixel count, a 1080i HDTV image is 6 - 9 times better than a standard, NTSC image• Audio is also improved.
  17. 17. HDTV & SDTV Comparison
  18. 18. Advantages• By using lower-definition signals, one channel can be split into several channels• Extra channels used for: – information services (datacasting) – music – Internet services
  19. 19. HDTV Features• Provides up to 60 frames/sec screen writing rate• Uses MPEG-2 data compression – source info data rate is 1.2Gbps – broadcast data rate is 20Mbps• Square pixels 1/4 the size of analog TV’s pixels
  20. 20. Type Of HDTV Type Advantage Disadvantage Heavy, max screen size limited,Direct View (CRT) Cheap (if you can find one) soon to be obsolete Competitive price, suitable for rooms Motion blur more apparent than LCD with high ambient light Plasma Brighter colors, less motion blur, wider More power consumption than Plasma viewing angle LCD, less competitive price More bulky then flat panel, moreRear Projection Larger screen size at lower cost components to fail Costly installation, not suitable forFront Projection Best solution for screens over 60 inches rooms with high ambient light 20
  21. 21. Connecting To Analog TV Composite DVD Or S-Video Compositeor or S-Video Composite or Composite From VCR (if available) or S-Video S-Video From VCR COAX VCR
  22. 22. Connecting To Digital TVDigital Signal from Cable or Satellite Component, Composite DVD Or S-Video or Composite or S-Video Component From VCR Or HDMI Composite or COAX S-Video Cable or Satellite VCR
  23. 23. Impact of HDTV• Broadcasters & consumers spend more $• Increased visual clarity has forced designers to spend considerably more money on sets, set dressings• Blu-Ray vs HD-DVD
  24. 24. Future of HD• DEC 2012: All commercial stations must begin digital broadcasts• Move will be cheaper, quicker, and easier as products and services become more widespread and people grow accustomed to the new technology.• Super HD TV
  25. 25. Conclusion• As NTSC retires, HDTV programming, products, and production services will continue to grow exponentially.• HDTV has brought a more cinematic experience into viewer’s homes and with digital cinema, delivered the film industry a few of the benefits of television. However, HDTV still has much lower resolution than 70mm film. It’s a matter of time before some will begin pressuring for another increase in quality.
  26. 26. Questions 26