The Second Information Superhighway was…
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Transcript of The Second Information Superhighway was…
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 currents With the discovery that electrical currents can induce magnetic fields, there was can induce magnetic fields, there was now an way to transmit electrical signals now an way to transmit electrical signals over wires and to detect small currents over wires and to detect small currents traveling in wires at a receiver.traveling in wires 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 Woodblock Printing in 200 AD200 AD
► Block printing was Block printing was suitable since character suitable since character alignment is not critical alignment is not critical with the Chinese with the Chinese languagelanguage
► Moveable Type Moveable Type impractical with 5000 impractical with 5000 basic Chinese basic Chinese characterscharacters
http://en.wikipedia.org
European languages offered distinct advantagesover Chinese, leading to wider dissemination ofwritten materials and greater range of materials.
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 was his electromagnetic telegraph. It was later replaced by the key transmitter.later replaced by the key transmitter.
A series of Clicks and ClacksWere transmitted to the receiver.
A weak current fromThe sender activatesa relay that connectsa battery to the sounder.
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
In 1864 Maxwell proves mathematically In 1864 Maxwell proves mathematically that changes in electrical current will that changes in electrical current will produce an electromagnetic wave; a produce an electromagnetic wave; a radiation (radio) wave.radiation (radio) wave.
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.”
First wireless communications in First wireless communications in 18951895
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.org http://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
Transmission of VoiceTransmission of VoiceLater Edison’s Phonograph and Telephone Later Edison’s Phonograph and Telephone technologies would be applied to telegraph technologies would be applied to telegraph technology to create the transmission of technology to create the transmission of voice and music.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.
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 but 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 1876sound waves (pressure wave) into electrical signals in 1876
Wikipedia
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
Bell patents the electro-magnetic Bell patents the electro-magnetic transmission of vocal sound by transmission of vocal sound by
undulatory electric currentundulatory electric current
http://sln.fi.edu
http://www.acmi.net.au
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
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 and others had many iterations of transmitters and receivers using various technologies.
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)
The Telephone ReceiverThe Telephone Receiver
http://www.privateline.com
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
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 with an analog electrical signal matching the sound wave.
http://www.exnet.btinternet.co.uk
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.
Modern PhonesModern Phones►Piezoelectric Piezoelectric
transducers convert transducers convert electrical signals into electrical signals into mechanical stressmechanical stress
►Electret Microphones Electret Microphones replace carbon based replace carbon based micsmics
Edison’s Other InventionsEdison’s Other InventionsThe 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 Transmitting
dots and dashes dots and dashes (digital) required (digital) required a human a human computer to computer to decode the decode the message.message.
►Speed was slowSpeed 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 first was the world's first radio station with radio station with scheduled 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
This is Frequency Modulation (FM).This requires greater bandwidth but it is easier to cancel out noise.
Turned into a Electromagnetic Wave
Electromagnetic Spectrum used Electromagnetic Spectrum used for Communicationfor Communication
www.sfu.ca/sonic-studio
Entire E&M Entire E&M SpectrumSpectrum
www.electrosensitivity.org
►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 Mississippi Stations west of the Mississippi
start with a K; east of the river start with a K; east of the river stations begin with Wstations begin with W