The Second Information The Second Information Superhighway was…Superhighway was…

Passing current in wires to transmit Passing current in wires to transmit information over long distances.information over long distances.

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

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

the 1400’sthe 1400’sJohannes Gutenberg’s movable-type printing Johannes Gutenberg’s movable-type printing press promoted the spread of knowledge. press promoted the spread of knowledge. Information did not have to come from clerics and Information did not have to come from clerics and royalty.royalty.

Wikipedia

A&E Network voted Johannes Gutenberg "Man of the 2nd Millennium"

Impacts of the Printing PressImpacts of the Printing Press

►Rise in Protestant ReformationRise in Protestant Reformation►Availability of Greek and Roman Availability of Greek and Roman

classic literature, leading to the classic literature, leading to the RenaissanceRenaissance

►Decline in the use of LatinDecline in the use of Latin►Greater dissemination of scientific Greater dissemination of scientific

informationinformation

Printing Press & the Chinese Printing Press & the Chinese LanguageLanguage

► Chinese developed Chinese developed Woodblock Printing in 200 Woodblock Printing in 200 AD and Movable Block AD and Movable Block printing on 1000 ADprinting on 1000 AD

► Using block printing, each Using block printing, each page is a carved block of page is a carved block of woodwood

► Moveable Type, where Moveable Type, where each character is printed each character is printed separately, was still separately, was still difficult since Chinese difficult since Chinese language has 5000 basic language has 5000 basic characters.characters.

http://en.wikipedia.org

European languages offered distinct advantagesover Chinese, leading to wider dissemination ofwritten materials and greater range of materials.

26 characters vs. 1000’s26 characters vs. 1000’s

► True mass True mass printing could printing could only thrive in a only thrive in a culture with a less culture with a less sophisticated sophisticated writing system. writing system.

► A language with A language with an alphabet of an alphabet of few characters few characters took advantage of took advantage of the benefits of the benefits of movable type movable type printing.printing. http://www.scottberkun.com/blog/2006/09/

http://www.computersmiths.com/chineseinvention/movtype.htm

Now back to the 2Now back to the 2ndnd Information Information Superhighway…Superhighway…

Using wires to transmit informationUsing wires to transmit information

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

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

A series of Clicks and Clacks or short andlong buzzes were transmitted to the receiver.

A weak current fromThe sender activatesa relay that connectsa battery to the buzzer.

Using $30,000 obtained from Using $30,000 obtained from congress, Morse builds a 40 mile congress, Morse builds a 40 mile telegraph line from telegraph line from

Washington DC to Baltimore.Washington DC to Baltimore.

In 1844, the first message is sent:In 1844, the first message is sent:

““What hath God wrought?”What hath God wrought?”

.-- .... .- - / .... .- - .... / --. --- -.. / .-- .-. --- ..- --. .... -

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

Transmission of VoiceTransmission of Voice

Thomas Edison’s Phonograph and Telephone Thomas Edison’s Phonograph and Telephone technologies is applied to telegraph technologies is applied to telegraph technology to create the transmission of technology to create the transmission of voice and music over long distances.voice and music over long distances.

Without wires - Without wires - This is radio.This is radio.Using wires - Using wires - this is what we typically think this is what we typically think of as basic telephone technology.of as basic telephone technology.

The first transatlantic wireless phone call The first transatlantic wireless phone call was in 1915.was in 1915.

Dots and Dashes are Dots and Dashes are digitaldigitalVoice and Music are Voice and Music are analoganalog

►Digital is coding a signal using a binary Digital is coding a signal using a binary format, e.g. 0’s and 1’s, dots and format, e.g. 0’s and 1’s, dots and dashes, on and offdashes, on and off

►Analog is the process of converting a Analog is the process of converting a signal into a wide range of continuous signal into a wide range of continuous values.values.

www.bbc.co.uk

http://photo.net/equipment/digital/basics

Photographic picture is an analog image.

Digital picture is a digital image – it is made up of many pixels.

http://jvsc.jst.go.jp

Analog sound waves can be stored directly in their analog form by cutting grooves on vinyl.

http://www.optics.rochester.edu

Alexander Graham Bell and the Alexander Graham Bell and the TelephoneTelephone

► Very interested in assisting the deaf. Both his motherVery interested in assisting the deaf. Both his motherand wife were deaf. and wife were deaf.

► Devised hearing aidesDevised hearing aides► Taught in a school for the deafTaught in a school for the deaf► Used the concept of Electromagnetic Induction to convertUsed the concept of Electromagnetic Induction to convert

sound waves (pressure wave) into electrical signals in sound waves (pressure wave) into electrical signals in 18761876

Wikipedia

Bell patents the ‘electro-magnetic’ Bell patents the ‘electro-magnetic’ transmission of vocal sound by means of transmission of vocal sound by means of

an electric current.an electric current.

http://sln.fi.edu

http://www.acmi.net.au

Sound is a pressure wave that will cause a

diaphram to vibrate in response to it.

Bell’s First Telephone-Bell’s First Telephone-Liquid TransmitterLiquid Transmitter

http://www.juliantrubin.com

The sound wave vibrates the diaphragmthat in turn moves a rod up and down.This changes the resistance making thecurrent change in consort with the soundwave.

An electrical current is produced that matches the pattern of the sound wave.

Electro-Magnetic ReceiverElectro-Magnetic Receiver(a speaker)(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.

A Watershed MomentA Watershed MomentMarch 10, 1876March 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

http://www.ctol.org.uk

Bell and others had many iterations of transmitters and receivers using various technologies.

The Telephone The Telephone Receiver/speakerReceiver/speaker

http://www.privateline.com

http://www.telephonecollecting.org MIC – microphoneREC - receiver

Electromagnets used in Electromagnets used in Tape Players tooTape Players too

A – Tape

HowStuffWorks

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.