Introduction to Digital Broadcast


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Lectures from Broadcast Multimedia course held at TUT

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Introduction to Digital Broadcast

  1. 1. Introduction to Digital Video Broadcast...... Adrian Hornsby Broadcast Multimedia 10/29/08
  2. 2. Broadcast communications … 10/29/08
  3. 3. Broadcast communications … 10/29/08
  4. 4. Broadcast communications … 10/29/08 Great fire New York - 1835
  5. 5. Broadcast communications … and authentication mechanism 10/29/08
  6. 6. Morse signal communication… 10/29/08 <ul><li>Morse-Vail Telegraph Key, 1844-1845 </li></ul><ul><li>Vail helped Morse develop a practical system for sending and receiving coded electrical signals over a wire, which was successfully demonstrated in 1844. </li></ul>
  7. 7. Voice communication … 10/29/08 In 1876, Alexander Graham Bell &quot;Mr. Watson. Come here! I want you!&quot;
  8. 8. Radio … 10/29/08 <ul><li>1860s, Scottish physicist, James Clerk Maxwell predicted the existence of radio waves </li></ul><ul><li>1886, German physicist, Heinrich Rudolph Hertz demonstrated that rapid variations of electric current could be projected into space in the form of radio waves. </li></ul><ul><li>1895 ,Guglielmo Marconi, Italian inventor, sent and received his first radio signal, in 1899 across the English Channel and two years later received the letter &quot;S&quot;, from England to Newfoundland. </li></ul><ul><li>Nikola Tesla and Nathan Stufflefield took out patents for wireless radio transmitters. Nikola Tesla is now credited with being the first person to patent radio technology; the Supreme Court overturned Marconi's patent in 1943 in favor of Tesla. </li></ul>
  9. 9. Television … 10/29/08 <ul><li>Television started in the 1920s as a Peepshow device. </li></ul><ul><ul><li>one viewer , 30 lines, tiny vertical screens, </li></ul></ul><ul><ul><li>received in a large part of Europe via the 'short wave', also used for radio. </li></ul></ul><ul><li>Audio sound was a separate short wave radio broadcast. </li></ul>
  10. 10. Transistors … 10/29/08 <ul><li>John Bardeen, Walter Brattain and William Shockley at Bell Labs in 1947 </li></ul><ul><ul><li>First practical application a hearing aid in 1952 </li></ul></ul><ul><ul><li>Nobel Prize in 1956. </li></ul></ul>2008, transistor made out of graphene, one atom thick and ten atoms across
  11. 11. Pulse Code Modulation … <ul><li>Pulse code modulation was first disclosed in a patent issued to Paul M. Rainey of Western Electric in 1921. </li></ul><ul><li>Method to transmit facsimile information in coded form over a telegraph line using an optical mechanical analog to digital converter. </li></ul>10/29/08
  12. 12. Analog to Digital conversion 10/29/08
  13. 13. New transmission systems … 10/29/08 The Sputnik program launched by the Soviet Union on October 4, 1957 The Russian word sputnik literally means &quot;co-traveler&quot;, &quot;traveling companion&quot; or &quot;satellite”
  14. 14. Digital revolution … New transmission, storage systems 10/29/08 August 17th, 1982, the first Compact Disk (ABBA's the Visitors) came off the assembly line; 200 billion followed it. J
  15. 15. Digital revolution … New media devices 10/29/08 <ul><li>First digital camera prototype in 1975 by Kodak </li></ul><ul><ul><li>100 line black and white image </li></ul></ul><ul><ul><li>recorded to a cassette tape </li></ul></ul><ul><ul><li>took 23 seconds to write. </li></ul></ul>
  16. 16. Digital revolution … New media devices 10/29/08
  17. 17. Digital Media Revolution … <ul><li>Huge increase in media content </li></ul><ul><li>Faster communications </li></ul><ul><li>New user experience </li></ul><ul><li>New consumer demand </li></ul>10/29/08 New digital devices + new digital transmission systems = New digital transmission standard
  18. 18. DVB was born … <ul><li>1991, European Launching Group (ELG)‏ </li></ul><ul><li>-> Overseeing the evolution of digital television and its distribution in Europe </li></ul><ul><li>September 1993, ELG renamed to DVB and becomes the major driving force in digital TV developement in Europe </li></ul>10/29/08
  19. 19. Digital Video Broadcasting Satellite <ul><li>DVB-S, first standard for digital transmission over satellite system in december 1993 - (EN 300 421)‏ </li></ul><ul><li>Original DVB forward error coding and modulation standard for satellite television </li></ul>10/29/08
  20. 20. DVB-S in short … <ul><ul><li>data insterted fixed length MPEG2-TS forming the payload. </li></ul></ul><ul><ul><li>Stream modulated using single QPSK (Quadrature Phase Shift Keyring) carrier modulation </li></ul></ul><ul><ul><ul><li>QPSK: phase of the carrier wave is modulated to encode bits in each phase change. Bits are mapped to phase changes rather than to an absolute transmitted phase. </li></ul></ul></ul><ul><ul><li>Additional tools for channel coding and error protection </li></ul></ul><ul><ul><li>Design for Standard Definition Television (SDT) services </li></ul></ul>10/29/08 Initial state
  21. 21. Digital Video Broadcasting Cable <ul><li>March 1994, DVB publishes DVB-C, addressing cable distribution system - EN 300 429 </li></ul><ul><li>Transmission of MPEG-2 or MPEG-4 family digital A/V stream, using a QAM modulation with channel coding </li></ul>10/29/08
  22. 22. DVB-C in short … <ul><li>DVB-C uses QAM </li></ul><ul><li>input stream is divided into groups of bits. </li></ul><ul><li>In 8QAM, each three bits of input, which provides eight values (0-7) changes the phase and amplitude of the carrier to derive eight unique modulation states </li></ul>10/29/08
  23. 23. Digital Video Broadcasting Terrestrial <ul><li>December 1995, DVB publish the DVB-T standards (EN 300 744)‏ </li></ul><ul><li>Transmission of compressed digital data (A/V) in MPEG-TS (transport stream), using OFDM modulation with concatenated channel coding (COFDM). </li></ul>10/29/08
  24. 24. DVB-T in short … <ul><li>Satellite vs Terrestrial </li></ul><ul><ul><li>Different environment, different propagation </li></ul></ul><ul><ul><ul><li>Multipaths effect </li></ul></ul></ul>10/29/08
  25. 25. DVB-T in short … <ul><li>OFDM was born: A single stream of data is split into parallel streams each of which is coded and modulated on to a subcarrier </li></ul><ul><li>Each sub-scarrier is modulated with conventional schemes (QAM, QPSK)‏ </li></ul>10/29/08
  26. 26. Analog vs Digital <ul><li>The success of DVB-T has led to the Analog Switch Off (ASO)‏ </li></ul>10/29/08 Analog Digital
  27. 27. Personal portable devices … 10/29/08
  28. 28. Personal portable devices… 10/29/08
  29. 29. Mobile phones … 10/29/08 Users worldwide
  30. 30. Digital Video Broadcasting Handheld <ul><li>DVB-H (Digital Video Broadcasting - Handheld) was formally adopted as ETSI standard EN 302 304 in November 2004 </li></ul><ul><li>Aims to provide digital TV to mobile devices </li></ul><ul><li>Combines traditional television broadcast standards with elements specific to handheld devices </li></ul><ul><ul><li>mobility, smaller screens and antennas, indoor coverage and reliance on battery power </li></ul></ul>10/29/08
  31. 31. Then came along High Definition TV … 10/29/08 <ul><li>Your new HDTV needs an HD feed </li></ul><ul><li>Most TV program still in standard definition </li></ul><ul><li>SD typically looks terrible on an HDTV </li></ul>
  32. 32. DVB-S2 … <ul><li>Developed in 2003 and ratified by ETSI (EN 302307) in March 2005 </li></ul><ul><li>The development of DVB-S2 coincided with the introduction of HDTV and H.264 (MPEG-4 AVC)‏ </li></ul><ul><li>Transmission of one or more MPEG-2 A/V streams , using QPSK or 8PSK or MAPSK (M-ary amplitude and phase shift keying) modulation with concatenated encoding. </li></ul><ul><li>Changing encoding parameters in real time (VCM, Variable Coding and Modulation)‏ </li></ul><ul><li>ACM (Adaptive Coding and Modulation) which optimizes the transmission parameters for various users. </li></ul>10/29/08
  33. 33. DVB-T2 (BBC-T2) … <ul><li>OFDM modulation with a large number of sub-carriers (up to 256)‏ </li></ul><ul><li>LDPC (Low Density Parity Check) coding combined with BCH (Bose-Chaudhuri-Hocquengham) for error correction </li></ul><ul><li>options : number of carriers, guard interval sizes and pilot signals to minimize the overheads for any channel. </li></ul><ul><li>New Rotated Constellations technique for additional robustness </li></ul><ul><li>Separate adjustment of each delivered service also allowing tailored transmissions (decoding only a single program rather than a whole multiplex)‏ </li></ul><ul><li>Transmitter diversity method (Alamouti coding)‏ </li></ul><ul><li>Future Extension Frames for compatible extensions </li></ul>10/29/08
  34. 34. Other DVB standards … <ul><li>DVB-SH, Satellite services to Handheld devices (SH) below 3 GHz </li></ul><ul><li>DVB-SI, Service information </li></ul><ul><li>DVB-IPDC, Internet Protocol Datacasting </li></ul><ul><li>DVB-IPTV, Framework for the Delivery of DVB-Services over IP-based Networks </li></ul><ul><li>DVB-GSE, Generic Stream Encapsulation (GSE) Protocol </li></ul><ul><li>Etc … </li></ul>10/29/08
  35. 35. Life of a standard … <ul><li>1 ) Commercial Module based on market needs. </li></ul><ul><ul><li>set of user requirements that outline the user functions, timescales and price range. </li></ul></ul><ul><li>2 ) A DVB specification developed in the Technical Module and its Working Groups. </li></ul><ul><ul><li>technological implications examined and available technologies are explored. </li></ul></ul><ul><li>3) The Steering Board gives final approval of the specification and offers it for standardization </li></ul><ul><li>New CALL for Technology DVB-C2 </li></ul>10/29/08
  36. 36. Exercises … <ul><li>[email_address] </li></ul><ul><li>Create a ’new n simple’ broadcast idea </li></ul><ul><ul><li>Commercial requirements (studies, trend, idea …)‏ </li></ul></ul><ul><ul><li>Technical requirements (research new R&D and apply it to your idea, and bring back the references)‏ </li></ul></ul><ul><ul><li>Present and advertise it among students, and bring back the proof. </li></ul></ul><ul><ul><li>Class will be the final steering board that gives the decision </li></ul></ul><ul><li>Good Presentation + good report + class happy = pass  </li></ul>10/29/08