The Second Information Superhighway was

1
The Second Information Superhighway was

• Passing current in wires to transmit information
  over long distances.
• With the discovery that electrical currents can
  induce magnetic fields, there was now an way to
  transmit audio as electrical signals over wires
  and to detect small currents traveling in wires
  at a receiver.

2
The First superhighway was the widespread release
of information as a result of the Printing Press
in the 1400s

• Johannes Gutenbergs movable-type printing press
  promoted the spread of knowledge. Information
  did not have to come from clerics and royalty.

AE Network voted Johannes Gutenberg "Man of the
2nd Millennium"
Wikipedia
3
Impacts of the Printing Press

• Rise in Protestant Reformation
• Availability of Greek and Roman classic
  literature, leading to the Renaissance
• Decline in the use of Latin
• Greater dissemination of scientific information

4
Printing Press the Chinese Language

• Chinese developed Woodblock Printing in 200 AD
  and Movable Block printing on 1000 AD
• Using block printing, each page is a carved block
  of wood
• Moveable Type, where each character is printed
  separately, was still difficult since Chinese
  language has 5000 basic characters.

European languages offered distinct
advantages over Chinese, leading to wider
dissemination of written materials and greater
range of materials.
http//en.wikipedia.org
5
26 characters vs. 1000s

• True mass printing could only thrive in a culture
  with a less sophisticated writing system.
• A language with an alphabet of few characters
  took advantage of the benefits of movable type
  printing.

http//www.computersmiths.com/chineseinvention/mov
type.htm
http//www.scottberkun.com/blog/2006/09/
6
Now back to the 2nd Information Superhighway

• Using wires to transmit information

7
Samuel Morse develops a code comprised of dots
and dashes.

• Morse is granted a patent in 1837 for his
  electromagnetic telegraph. It was later
  simplified and replaced by the key transmitter.

A weak current from The sender activates a relay
that connects a battery to the buzzer.
A series of Clicks and Clacks or short and long
buzzes were transmitted to the receiver.
8

• Using 30,000 obtained from congress, Morse
  builds a 40 mile telegraph line from
• Washington DC to Baltimore.
• In 1844, the first message is sent
• What hath God wrought?

.-- .... .- - / .... .- - .... / --. --- -.. /
.-- .-. --- ..- --. .... -
http//morsecode.scphillips.com/jtranslator.html

9
Transmission of Voice

• Thomas Edisons Phonograph and Telephone
  technologies is applied to telegraph technology
  to create the transmission of voice and music
  over long distances.
• Without wires - This is radio.
• Using wires - this is what we typically think of
  as basic telephone technology.
• The first transatlantic wireless phone call was
  in 1915.

10
Dots and Dashes are digitalVoice and Music are
analog

• Digital is coding a signal using a binary format,
  e.g. 0s and 1s, dots and dashes, on and off
• Analog is the process of converting a signal into
  a wide range of continuous values.

11
Photographic picture is an analog image.
www.bbc.co.uk
Digital picture is a digital image it is made
up of many pixels.
http//photo.net/equipment/digital/basics
12
Analog sound waves can be stored directly in
their analog form by cutting grooves on vinyl.
http//www.optics.rochester.edu
http//jvsc.jst.go.jp
13
Alexander Graham Bell and the Telephone

• Very interested in assisting the deaf. Both his
  mother
• and wife were deaf.
• Devised hearing aides
• Taught in a school for the deaf
• Used the concept of Electromagnetic Induction to
  convert
• sound waves (pressure wave) into electrical
  signals in 1876

14
Bell patents the electro-magnetic transmission
of vocal sound by means of an electric current.
http//sln.fi.edu
Sound is a pressure wave that will cause a
diaphram to vibrate in response to it.
http//www.acmi.net.au
15
Bells First Telephone-Liquid Transmitter
The sound wave vibrates the diaphragm that in
turn moves a rod up and down. This changes the
resistance making the current change in consort
with the sound wave. An electrical current is
produced that matches the pattern of the sound
wave.
http//www.juliantrubin.com
16
Electro-Magnetic Receiver(a speaker)
A changing current in the coil induces a changing
magnetic field around the coil. The force
between the permanent magnet and the coil causes
the diaphram to vibrate and reproduce the
original sound wave.
17
A Watershed MomentMarch 10, 1876
"I then shouted into M the mouthpiece the
following sentence 'Mr. Watson--come here--I
want to see you.' To my delight he came and
declared that he had heard and understood what I
said."
Wikipedia
18
Bell and others had many iterations of
transmitters and receivers using various
technologies.
http//www.ctol.org.uk
19
The Telephone Receiver/speaker
http//www.privateline.com
20
MIC microphone REC - receiver
http//www.telephonecollecting.org
21
Electromagnets used in Tape Players too
The electromagnet consists of an iron core
wrapped with wire, as shown in the figure. During
recording, the audio signal is sent through the
coil of wire to create a magnetic field in the
core. This flux is what magnetizes the oxide on
the tape. During playback, the motion of the tape
pulls a varying magnetic field across the gap.
This creates a varying magnetic field in the core
and therefore a signal in the coil.
A Tape HowStuffWorks