Why Digital is Better

1. Why Digital is Better ? — or is it David Holdsworth

2. Technical Words Digital Laser Quantum leap Lowest common denominator Black hole Megawatt Antibiotic Carbon dioxide DVD

3. Digital Age • We are living in the “digital decade”Bill Gates • National Consumer Council’s recent report Consumer Futures concludes that the over 65s and the poor are being excluded in our digital decade

4. Digital TV • Our area goes digital in 2009 • I.E. the old “analogue” signal will be switched off • Even more channels may appear

5. New Lamps for Old • Why turn off the old “analogue” signal? • We’ve already got the digital signal. • Is it a con? • This is not unprecedented. • Who remembers 405-line TV?

6. Radio Times 1969 Not allin colour

7. Radio Times 2007

8. Radio Times 2007

9. New Lamps for Old • Why turn off the old “analogue” signal? • We’ve already got the digital signal. • Is it a con? • This is not unprecedented. • Who remembers 405-line TV? • Who benefits? • What problem are we trying to solve?

10. Settle Ilkley Winter Hill Emley Moot

11. Otley Repeater • Receives the signal from Emley Moor • retransmits towards Ilkley BBC1, BBC2, ITV1, Channel 4 • on 4 new frequencies (i.e. channels) • no room for digital channels • Several digital channels are multiplexed onto one analogue channel

12. Everything is digital • Watches, clocks • Cameras, both still and video • Computers — nobody much uses analogue computers any more • Computers in cars, audio, video • Hearing aids • Credit cards — chip and PIN • Mobile ’phones • Barcodes

13. Digital • a word associated with computers • There used to be analogue computers and digital computers • Analogue has come to mean “not digital” in the library community • “Digital” is almost a brand name

14. An Analogue Computer Program

15. A Digital Computer Program showDatagram(p); // received packet if ( p.getData() != buff ) // unlikely ???? { buff = p.getData(); System.out.println("Buffer reallocated"); } function = buff[dhcpFunc]; // get function from client ip = 113; if ( ipnum > 256 ) // suppress all replies - just monitor traffic function += 2000; else if ( ipnum > 0 ) // specified as parameter ip = (byte)ipnum; else { i = 6; // check for my laptop or visitor while ( --i >= 0 && buff[i+28] == myLaptop[i] ) ; if ( i >= 0 ) // if not my laptop, i.e. visitor { ip = 112; if ( ipnum < 0 ) // if only serving my laptop function += 1000; // cause packet to be ignored } else if ( ipnum < 0 ) // if only serving my laptop ip = (byte) - ipnum; }

16. Concise Oxford Dictionary (c1984) • digit any numeral from 0 to 9 especially when forming part of a number • digital of digit(s) • ~ clock showing time by displayed digits, not by hands • ~ computer (making calculations with data represented by digits or in similar discrete form) • ~ recording (of sound represented by digits or in similar discrete form, to improve quality)

17. Digits • Decimal — 0 1 2 3 4 5 6 7 8 9 • Binary — 0 1 • Octal — 0 1 2 3 4 5 6 7 • Hexadecimal — 0 1 2 3 4 5 6 7 8 9 A B C D E F • Byte — 0 1 2 3 …… 255 i.e. 8 binary digits

18. Different ways of seeing 100 • Decimal — 100 • Binary — 1100100 • Octal — 144 • Hexadecimal — 64 • Byte — just a single byte (8 bits 01100100)

19. Morse Code • has two digits • and — • actually three because space or pause is significant

20. Sound • vibrating string vibrates the soundboard which vibrates the air • or reed or brass player’s embouchure • vibrating air vibrates the eardrum • all move “in step”

21. Vinyl Records • are analogue • The track on the record moves from side to side in a similar way (analagously) • On playback the stylus recreates the movement of the string/reed/etc • the amplifier causes the speakers to recreate the movement of the air • vibrating air vibrates the eardrum

22. Compact Discs — Recording • are digital • the sound wave is measured 44,000 times per second • each second of music produces 88,000 numbers (stereo) • These numbers are recorded “digitally” on the disc — 2 bytes (16 bits) each

23. Graph of sound wave

24. Graph of sound wave

25. Digitisation • This process of making a “copy” of something in the form of a list of numbers is called “digitisation” — or “digitization” in the USA • The French use the word “numerique” in many places where we use the word “digital”

26. Compact Discs — Playback • The numbers are read back from the disc — 2 bytes (16 bits) each • On playback the numbers recreate the sound wave — almost exactly • the amplifier causes the speakers to recreate the movement of the air • vibrating air vibrates the eardrum

27. Copies are perfect • The stream of 600,000,000 numbers can be copied • The copy is indistinguishable from the original • The record companies don’t like that

28. Radiohead • Latest album released for download • Pay what you like • Quotes from Tom Yorke“We did well out of it”“The Infrastructure [e.g. record companies]just get in the way and take all the cash” Today Programme 2 Jan 2008

29. Photographs — Still Pictures • Need to convert the image to a list of numbers — a lot of numbers • Divide the image into “pixels” — picture elements • Represent the brightness of each colour in each cell as a number

30. A Digital Picture

31. Pixel • How red is it? • How green is it? • How blue is it? • Three numbers — often 1 byte each i.e. 24-bit colour • 1280×960 pixels — 3,686,400 bytes

32. Compression • Exploit the similarity of neighbouring pixels • Can do this without loss of information • Exploit the eye’s imperfect colour vision • Lossy compression loses some information • Similar to colour TV • Joint Picture Experts Group = JPEG

33. 379235 bytes 1280×960 pixels — 3,686,400 bytes compressed to

34. Moving Pictures • Succession of images — called “frames” • Each frame is a digital image — i.e. a bundle of numbers • Compression exploits the similarity between successive frames • Motion Picture Experts Group = MPEG • Freeview uses MPEG-2

35. Compressed Sound • CD format is very wasteful of space • MP3 compression reduces by 90% • Digital TV transmission now needs much less than analogue • “Multiplex” 4 or 5 digital channels onto one analogue channel — called a multiplex • Send TV over broadband internet • iPOD downloads are MP3

36. The Internet • Entirely digital • Developed in late 60s and early 70s • Each e-mail message is a stream of numbersparcelled up into “packets” of about 1000 and sent over the internet to the mailserver used by the recipient • World Wide Web traffic uses the internet • WWW developed early 90s

37. The Internet • The design was given to the world by academia (funded in part by the US military) • Protocols can be used with no licenc(s)e fee • WWW design given to the world by CERN • Primarily the idea of one man, Tim Berners-Lee

38. Tiny Technology • Miniaturisation (both size and cost) leads to pervasive digital computing • Hearing aids — internal computer talks to hospital’s computer for set up • Credit card

39. Born Digital • e-mails • web pages • digital photos • income tax returns • airline tickets • ENG — electronic news gathering • Almost all official documents

40. Digital Death • Copies are perfect, but • Need good organisation to find them • lots of copies keep stuff safe — LOCKSS • Data Protection Legislation requires destruction — bad idea for historians • Digital Immortality is achievable as long as civilisation survives

41. Is it better?

42. Is it better? Hellifield Peel 

43. Is it better? Yes if you live in Ilkley — but not until 2012 In all sorts of ways Remember the world before barcodes

44. Is it better? Mostly

45. Kilogramme • The standard kilogramme lives in Paris • Several countries have their own copies • They no longer agree • We have no way of knowing which has changed • or by how much • These copies are analogue copies • The standard is “a copy of the ideal kg”

46. A Digital Kilogramme • Redefine as a count of something widely available • Get it as close as possible to the current standard • A silicon sphere in Australia • Silicon is the second most abundant element in the earth’s crust • We know how to make very pure crystals of silicon because that is what computers are made of

47. A Digital Kilogramme • The new standard will specify the number of atoms of silicon that weigh exactly one kilogramme • A very large number • A digital quantity that can be remembered exactly for ever

48. Human Memory • is not digital • We can have clear memories that are plain wrong

49. Is it better? Mostly