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 Councils 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?
• Weve 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?
• Weve 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("Bu
ffer reallocated")
function buffdhcpFunc // get function from
client ip 113 if (
ipnum gt 256 ) // suppress all replies -
just monitor traffic function
2000 else if ( ipnum gt 0 ) //
specified as parameter ip
(byte)ipnum else i
6 // check for my laptop or
visitor while ( --i gt 0
buffi28 myLaptopi ) if
( i gt 0 ) // if not my laptop, i.e.
visitor ip 112
if ( ipnum lt 0 ) // if only serving my
laptop function 1000 //
cause packet to be ignored
else if ( ipnum lt 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 players 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 dont like that

28
Radiohead

• Latest album released for download
• Pay what you like
• Quotes from Tom YorkeWe did well out of
  itThe Infrastructure e.g. record
  companiesjust 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
• 1280960 pixels 3,686,400 bytes

32
Compression

• Exploit the similarity of neighbouring pixels
• Can do this without loss of information
• Exploit the eyes imperfect colour vision
• Lossy compression loses some information
• Similar to colour TV
• Joint Picture Experts Group JPEG

33
379235 bytes
1280960 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
  hospitals 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 earths 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