An Information Superhighway An Information Superhighway prior to the internet was…prior to the internet was…

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

Shortly thereafter came Wireless Shortly thereafter came Wireless Telegraph; Telephone; and RadioTelegraph; Telephone; and Radio

The First Info. superhighway was The First Info. superhighway was the widespread release of the widespread release of

information as a result of the information as a result of the Printing Press in the 1400’sPrinting Press in the 1400’s

Johannes 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►Higher literacy ratesHigher literacy rates

Printing Press & the Chinese Printing Press & the Chinese LanguageLanguage

► Chinese developed Chinese developed Woodblock Printing Woodblock Printing (200AD) and Movable type (200AD) and Movable type printing.printing.

► Block printing was suitable Block printing was suitable since character alignment since character alignment is not critical with the is not critical with the Chinese language.Chinese language.

► Moveable Type printing Moveable Type printing was impractical with 5000 was impractical with 5000 basic Chinese charactersbasic Chinese characters

http://en.wikipedia.org

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

Brief Timeline of telegraph and Brief Timeline of telegraph and radioradio

1833:1833: Electrical Telegraph – using electricity in Electrical Telegraph – using electricity in wires to transmit information.wires to transmit information.

1835:1835: Relay is developed Relay is developed

1866:1866: First transatlantic cable is successfully laid First transatlantic cable is successfully laid on ocean floor, to be used for the electrical on ocean floor, to be used for the electrical telegraph.telegraph.

1876:1876: First telephone (wires used to transmit First telephone (wires used to transmit voice, not just Morse codes)voice, not just Morse codes)

1894:1894: First use of wireless telegraph (transmitting First use of wireless telegraph (transmitting Morse codes without the use of wires)Morse codes without the use of wires)

1906:1906: First radio broadcast (transmitting voice First radio broadcast (transmitting voice without wires)without wires)

Electrical Electrical TelegraphTelegraph

► In 1832, Baron Schilling (a Russian from In 1832, Baron Schilling (a Russian from Estonia) devised a communication Estonia) devised a communication device using wires to transmit signals device using wires to transmit signals between rooms of his homebetween rooms of his home

► In 1835-6, his system was tested at In 1835-6, his system was tested at distances of 5 km using underwater distances of 5 km using underwater cable.cable.

►First to use binary codes to transmit First to use binary codes to transmit messages.messages.

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. his electromagnetic telegraph.

A series of Clicks and ClacksWere transmitted to the receiver.

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

Sounder – Self Interrupting Sounder – Self Interrupting CircuitCircuit

http://home.howstuffworks.com/doorbell2.htm

Voltage Source

Switch or Relay

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 Morse code translator

Recall Maxwell’s EquationsRecall Maxwell’s Equations

1. Like charges repel, unlike charges attract1. Like charges repel, unlike charges attract

2. Magnetic fields always have two poles (positive and 2. Magnetic fields always have two poles (positive and negative)negative)

3. A moving/changing magnetic field can produce 3. A moving/changing magnetic field can produce current.current.

4. Moving electrical charge (current) can produce a 4. Moving electrical charge (current) can produce a magnetic field.magnetic field.

Maxwell Maxwell predicts predicts ElectromagnetiElectromagnetic c RadiationRadiation

An electromagnetic wave exists when the changing magnetic field causes an electric field which then causes another changing magnetic field, and so on forever.

These oscillating fields together form an electromagnetic wave.

An electromagnetic wave will travel at the speed of light and continue on forever until absorbed.

Wikipedia.com

In 1864 Maxwell proves mathematically that changes in In 1864 Maxwell proves mathematically that changes in electrical current will produce an electromagnetic wave; electrical current will produce an electromagnetic wave; a radiation (radio) wave.a radiation (radio) wave.Hertz then demonstrates existence of electromagnetic Hertz then demonstrates existence of electromagnetic waves.waves.Hertz’sSpark and Loop Experiment

In 1888, Heinrich Hertz proved Maxwell’s theories with this experiment.

Hertz said, “I don’t see any useful purpose for this invisible electromagnetic energy.”

1866 – Laying the transatlantic 1866 – Laying the transatlantic cablecable

►Five attempts to lay cable in 12 yearsFive attempts to lay cable in 12 years►1866 cable was able to transmit eight 1866 cable was able to transmit eight

words a minutewords a minute

http://www.cmhg.gc.ca

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 transmission of Bell patents the electro-magnetic transmission of vocal sound by undulatory electric current in vocal sound by undulatory electric current in

18761876

http://sln.fi.edu

http://www.acmi.net.au

Microphone

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.

With an Electro-Magnetic With an Electro-Magnetic ReceiverReceiver

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 had other iterations of transmitters and receivers using various technologies.

It is important to note that there is no one "inventor of the telephone" . Bell was merely the first to patent the telephone, an "apparatus for transmitting vocal or other sounds telegraphically", 16 years after Antonio Meucci, who did not have $10 to file a patent, demonstrated his electro-magnetic "teletrofono" in New York in 1860.

Wikipedia

A 2002 a resolution by the U.S. House of Representatives, gave its endorsement of

Antonio Santi Giuseppe Meucci

as the originator of the telephone.

HR 269

Timing is everything. Elisha Gray knew all too well just how true that old adage could be. On February 14, 1876, the day that Alexander Graham Bell filed an application for a patent for his version of the telephone, Elisha Gray applied for a caveat announcing his intention to file a claim for a patent for the same invention. PBS.org

Bell’s patent has been defended in 587 lawsuits.

Elisha Gray of Ohio

Thomas Edison makes Thomas Edison makes improvementsimprovementsBell’s telephones produced

weak electric signals limiting the quality and distance of the message.

Emile Berliner and soon thereafter Thomas Edison improved the sensitivity of sound detection at the transmitter (microphone) by replacing the parchment membrane with a disc of compressed carbon set between metal plates. The electrical resistance of carbon is extremely sensitive to the minute pressure changes caused by sound waves.

http://www.porticus.org

This Technology, improved later by substituting granulated carbon and then roasting the granules—became a basic component of telephones for almost a hundred years.

http://www.beatmag.net

The Carbon The Carbon Transmitter Transmitter

(microphone)(microphone)

When the carbon is pulsated by a sound wave, the resistance of the carbon button changes slightly.

This creates an electrical signal in the wires that matches the sound wave.

http://www.exnet.btinternet.co.uk

The Telephone ReceiverThe Telephone Receiver

http://www.privateline.com

http://www.exnet.btinternet.co.uk

The Current travels to the receiver and goes through a coil of wire. This induces a magnetic field which in turn causes the diaphragm to vibrate. This is a simple speaker.

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

http://www.exnet.btinternet.co.uk/T293/telephones.htmGood simple explanation of 20th century phones.

http://www.exnet.btinternet.co.uk

Dialing a number sends out pulses or clicks to the telephone exchange.

Dialing a ‘2’ will result in the switch opening and closing twice.

The exchange connects you with the line called.

Rotating Sprocket

Try this experiment at homeTry this experiment at home

Dial 411 by pressing on the switchhook Dial 411 by pressing on the switchhook (the button on the phone’s cradle)(the button on the phone’s cradle)

1.1. Hit the switchhook 4 times fastHit the switchhook 4 times fast2.2. Hit the switchhook once, briefly wait, Hit the switchhook once, briefly wait,

thenthen3.3. Hit the switchhook again once.Hit the switchhook again once.

You just dialed 411You just dialed 411

Modern PhonesModern Phones

► Piezoelectric transducers Piezoelectric transducers convert electrical signals convert electrical signals into mechanical stressinto mechanical stress

► Electret Microphones Electret Microphones replace carbon based replace carbon based micsmics

► Touchtone phones Touchtone phones introduced in 1963. introduced in 1963. Each button produces a Each button produces a DTMF tone.DTMF tone.

DTMF – Dual Tone Multi- Frequency

First First wirelesswireless communications in communications in 1895 using Morse codes1895 using Morse codes

Alexander Popov sent over a distance of 600 meters

Guglielmo Marconi sent messages to his brother within the grounds of his Bologna estate.

http://en.wikipedia.orghttp://www.mlahanas.de

The Coherer Tube (filled with The Coherer Tube (filled with iron shavings) was the Receiveriron shavings) was the ReceiverWhen the coherer detected a radio wave, When the coherer detected a radio wave, the resistance in the tube changed causing the resistance in the tube changed causing the bell to ring. The wave was created by a the bell to ring. The wave was created by a distant spark.distant spark.

Guglielmo Marconi obtains a patent Guglielmo Marconi obtains a patent for wireless telegraphy in 1896for wireless telegraphy in 1896

In 1901, the letter ‘S’ is sent from Cornwall to In 1901, the letter ‘S’ is sent from Cornwall to Newfoundland.Newfoundland.

This proved that wireless telegraphy was possible This proved that wireless telegraphy was possible (and fast) over long distances.(and fast) over long distances.

All electromagnetic waves travel at 186,000 All electromagnetic waves travel at 186,000 miles/sec in a vacuum. (speed of light)miles/sec in a vacuum. (speed of light)

Wireless Room on board RMS Olympic,the sister ship to the Titanic.Wireless technology saves 706 lives afterthe Titanic sinks in 1912.

http://www.evaluationengineering.com

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 but cutting grooves on vinyl.

http://www.optics.rochester.edu

Transmission of VoiceTransmission of Voice

Edison’s Phonograph and Telephone Edison’s Phonograph and Telephone technologies were also applied to wireless technologies were also applied to wireless telegraph technology to create the telegraph technology to create the transmission of voice and music.transmission of voice and music.

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.

Edison’s Other InventionsEdison’s Other Inventions

The Phonograph in 1877 used The Phonograph in 1877 used telephone technology to record telephone technology to record sounds on a wax cylinder.sounds on a wax cylinder.

Smithsonian

The first voice recorder

birminghamstories.co.uk

http://www.nps.gov

Record Needle - StylusRecord Needle - Stylus

Contacts the recorded disc and transfers Contacts the recorded disc and transfers its vibrations to the rest of the system its vibrations to the rest of the system

As the stylus rides along the walls of the moving groove, it vibrates back and forth with each ripple in a wall. Two transducers attached to this stylus sense its motions and produce electric currents that are related to those motions. The two most common transduction techniques are electromagnetic (a coil of wire and a magnet move relative to one another as the stylus moves and this causes current to flow through the coil)

Louis A. Bloomfield http://www.answers.com

Transducer:converts input energy of one form into output energy of another.

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.

Wireless transmission of Analog Wireless transmission of Analog DataData

(“Listening to the Radio”)(“Listening to the Radio”)

►Transmitting dots and dashes Transmitting dots and dashes (digital) required a human (digital) required a human computer to decode the message.computer to decode the message.

►Sending Morse codes was slowSending Morse codes was slow

First radio broadcast of audio on First radio broadcast of audio on Christmas Eve in 1906 Christmas Eve in 1906

Reginald Fessenden, CanadianReginald Fessenden, Canadian

Fessended commemorates this event by playing “O Holy Night” on the Violin

First radio stations in the USFirst radio stations in the US

► WWJ in DetroitWWJ in Detroit► KDKA in PittsburgKDKA in Pittsburg► In 1920, the results In 1920, the results

of the presidential of the presidential election were election were broadcasted.broadcasted.

► ““San Jose Calling” San Jose Calling” was the world's was the world's first radio station first radio station with scheduled with scheduled programming in programming in 1910 (now known 1910 (now known as KCBS)as KCBS)

TransmissionTransmission

This is Amplitude Modulation (AM)

Carrier Wave’s amplitude is modulated

http://www.answers.com

Turned into a Electromagnetic Wave

Amplitude is volume and frequency is the pitch.

Audible range:20 Hz - 20 kHz

Audio

This is Frequency Modulation (FM).

This requires greater bandwidth but it is easier to cancel out noise.

Turned into a Electromagnetic Wave

Electromagnetic SpectrumElectromagnetic Spectrum

http://www.lbl.gov/MicroWorlds/ALSTool/EMSpec/EMSpec2.html

►AM Band - 520-1700 kHz AM Band - 520-1700 kHz ►FM Band - 87.5 to 108.0 MHzFM Band - 87.5 to 108.0 MHz►Stations west of the Stations west of the

Mississippi start with a K; east Mississippi start with a K; east of the river stations begin with of the river stations begin with WW