TVU Tech Episode 1 extra information


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this is A slide show that helps Illustrate the fundamentals of digital and analog broadcasting

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TVU Tech Episode 1 extra information

  1. 1. Fundamentals of Analogue and Digital Broadcasting BSc. Media Technology May 2007
  2. 2. Q. Is it inevitable that all broadcasting will go digital? <ul><li>The radio spectrum is a finite resource </li></ul><ul><li>Society today wants more choice, more TV channels, more phones, etc. </li></ul><ul><li>Digital broadcasting makes more efficient use of the available radio frequency bandwidth </li></ul>
  3. 3. Q. Is it inevitable that all broadcasting will go digital? <ul><li>Analogue TV switch off planned to start in 2007 - 2012 </li></ul><ul><li>Digital distribution over the Internet is breaking down all the old models of broadcasting and traditional retail </li></ul>
  4. 4. <ul><li>Analogue </li></ul><ul><li>Digital </li></ul><ul><li>Bandwidth </li></ul><ul><li>Compression </li></ul>Common Terms
  5. 5. Define the term Analogue: <ul><li>A continuous analogy of a sound or light wave transmitted as an electrical signal, which is an alternating voltage (A/C) </li></ul><ul><li>Any audio or video equipment that has analogue signals going through it </li></ul><ul><li>Old equipment! </li></ul>
  6. 6. A/C signal Volts + - Time
  7. 7. Waveforms: Sine waves Complex waves
  8. 8. Analogue: <ul><li>Audio signals </li></ul><ul><li>Video signals </li></ul><ul><li>Problems: Distortion, not robust, large bandwidth signals </li></ul>
  9. 9. <ul><li>101100110100100111001001010110111010010010001001001010010 </li></ul>Digital
  10. 10. Define the term Digital: <ul><li>Represent all signals or data with binary numbers, 0 or 1 </li></ul><ul><li>Turns audio and video signals into discrete values, e.g. snapshot measurements of the a/c voltage waveform at regular points in time </li></ul><ul><li>Is this a new technology? </li></ul>
  11. 11. PCM - Pulse Code Modulation + 2 = (10010011), + 4 = (10010100), - 1 = (01101100) Voltage Time 5 4 3 2 1 0 1 2 3 4 5 + -
  12. 12. PCM - Pulse Code Modulation Volume Time
  13. 13. Advantages: <ul><li>Robust </li></ul><ul><li>Can be copied and cloned </li></ul><ul><li>No distortion </li></ul><ul><li>Can take up less bandwidth than analogue when compressed </li></ul>
  14. 14. Bandwidth
  15. 15. Bandwidth <ul><li>This defines the maximum amount of information we can transmit through a given channel or connection </li></ul><ul><li>Could be described as how much water you can get through a pipe </li></ul>
  16. 16. Bandwidth <ul><li>In analogue broadcasting this is how much of the radio spectrum is used by the TV channel or radio station </li></ul><ul><li>In digital broadcasting: How many ‘bits per second’ </li></ul>
  17. 17. Electro-magnetic Radio Spectrum
  18. 18. 30 GHz EHF 3 GHz SHF 300MHz UHF 30MHz VHF 3 MHz 300 KHz 30 KHz Radio Spectrum 150 -300 KHz Long Wave AM 500 -1600 KHz Medium Wave AM 6 -18MHz Short Wave AM 88 -108 MHz FM 10.7 -12.7 GHz Satellite TV 217 -230 MHz DAB radio 470 -840 MHz Terrestrial TV 1800 MHz PCN Mobile phones 900 MHz GSM Mobile phones 2320 - 2345 S Band Digital Radio 1470 - 1490 MHz L Band Digital Radio Other used frequencies: Police, emergency services, military, navigation, CB radio, toys, microphones,WiFi, Bluetooth, etc.
  19. 19. Bandwidth Examples showing bits per second Modem 56 kbit ADSL 4 Mbit CD audio 1.4 Mbit DVD 9.6 Mbit HDTV & DV video 25 Mbit BluRay disc 54 Mbit/sec
  20. 20. Compression
  21. 21. Compression <ul><li>Digital broadcasting would not be possible without data compression </li></ul><ul><li>Compression also achieves the goal of efficient use of the airwaves </li></ul><ul><li>We can now fit 6 - 8 digital TV channels into the same RF bandwidth as one old analogue TV channel </li></ul>
  22. 22. Codecs <ul><li>Short for co de - dec ode </li></ul><ul><li>A mathematical algorithm describing how to reduce the size of the data </li></ul><ul><li>Can be a Lossless or Lossy process </li></ul><ul><li>Can be built into a hardware device or software running on a computer </li></ul>
  23. 23. Codec examples: <ul><li>Video : MPEG 1, MPEG 2, DivX, Windows Media video, MPEG 4 - H.264 </li></ul><ul><li>Audio: MP3, ATRAC, AAC, Windows Media audio, DTS, Dolby Digital AC3, Real Audio, Ogg Vorbis, MLP lossless </li></ul><ul><li>Image: JPEG, JPEG2000, PNG, Gif, </li></ul><ul><li>Data: Zip, Stuffit </li></ul>
  24. 24. Compression Examples stereo audio files AAC-HE 48 kbit/sec Uncompressed CD audio 1.4 Mbit/sec MiniDisc 282 Kbit/sec MP3 128 Kbit/sec
  25. 25. Summary: <ul><li>The global society is entering the digital information age </li></ul><ul><li>All media production is becoming completely digital from start to finish </li></ul><ul><li>For efficiency all broadcasting is going digital </li></ul>