From Morse Code to From Morse Code to Gigabit EthernetGigabit Ethernet

Lisa MarvelLisa Marvel

US Army Research LaboratoryUS Army Research Laboratory

Information presented here is, for the most part, based on C. Boncelet, “THE INVENTION OF THE TELEGRAPH MARKS THE BEGINNING OF ELECTRICAL ENGINEERING,” July 2011.

OutlineOutline

Some interesting historySome interesting history Computer communication todayComputer communication today Morse Code activityMorse Code activity Video clipVideo clip

History: 200 years agoHistory: 200 years ago

200 years ago is not so long ago200 years ago is not so long ago Scientist just beginning to experiment with Scientist just beginning to experiment with

electricityelectricity How was communication performed 200 How was communication performed 200

years ago?years ago?

News traveled slowly …News traveled slowly …

War of 1812 War of 1812 Battle of New Orleans January 8, 1815Battle of New Orleans January 8, 1815 But peace treaty signed on December 24 But peace treaty signed on December 24

18141814 ????

Elections Elections Held in NovemberHeld in November Inauguration in MarchInauguration in March

1837: Communications speed up1837: Communications speed up

Samuel Morse invents the telegraphSamuel Morse invents the telegraph The switch and sounder could be located at The switch and sounder could be located at

separate locations limited mostly by the length separate locations limited mostly by the length of wire availableof wire available

Information could be carried by a changing Information could be carried by a changing electrical currentelectrical current

Electrical CommunicationElectrical Communication

Changing electrical current Changing electrical current Signals of high/low voltage/currentSignals of high/low voltage/current Represent 1s and 0s for communication Represent 1s and 0s for communication

and computationand computation This was a BIG (read HUGE) deal!This was a BIG (read HUGE) deal!

Electrical InfrastructureElectrical Infrastructure

Soon after the telegraph invention, wires Soon after the telegraph invention, wires were strung everywhere!were strung everywhere!

Messages could be sent “instantly” over Messages could be sent “instantly” over long distanceslong distances

Telegraph first electrical device to come Telegraph first electrical device to come into widespread useinto widespread use

Can you name the US telegraph Can you name the US telegraph company? What do they do today?company? What do they do today?

““Wire” TransfersWire” Transfers

Western Union OfficesWestern Union Offices Send $ from person in one town to anotherSend $ from person in one town to another Send $100 to Aunt Doris …Send $100 to Aunt Doris …

$ do not move but the $ pass over the $ do not move but the $ pass over the “wire”“wire”

Telegraph invention led to the invention of Telegraph invention led to the invention of the interstate banking systemthe interstate banking system

TelephoneTelephone

1876 Alexander Graham Bell invents the 1876 Alexander Graham Bell invents the telephonetelephone

Similar to telegraph Similar to telegraph switch -> microphoneswitch -> microphone Sounder -> loudspeakerSounder -> loudspeaker Transmits continuous signals vs. 1s 0sTransmits continuous signals vs. 1s 0s

Western union thought telephone a toyWestern union thought telephone a toy

Radio CommunicationsRadio Communications

1890s 1890s Ships were equipped with radios using Ships were equipped with radios using

Morse CodeMorse Code 1912 Titanic; survivors can thank radios1912 Titanic; survivors can thank radios 1920 Broadcast popular1920 Broadcast popular 1930s B/W Television 1930s B/W Television 1950s Color Television1950s Color Television

Originally Computers were …Originally Computers were … Human Human

Women Mathematicians -> “computers”Women Mathematicians -> “computers” Calculated firing tables Calculated firing tables

ENIAC – 1946ENIAC – 1946 Sponsored by ARL predecessor, BRLSponsored by ARL predecessor, BRL Was located @ APG Was located @ APG

Some of these women were the Some of these women were the first computer programmers!first computer programmers!

See DVD “Top-Secret Rosies: The female Computers of World War II”

Today …Today …

Personal Computers, commonplace by Personal Computers, commonplace by 1980s1980s

Cell phones (2-way radios), 1980sCell phones (2-way radios), 1980s Smart phone = radio + computerSmart phone = radio + computer It is not uncommon for a single person to It is not uncommon for a single person to

own/carry several computersown/carry several computers What other important technology did we What other important technology did we

fail to mention?fail to mention?

Computer NetworksComputer Networks There are fewer unconnected (stand alone) There are fewer unconnected (stand alone)

computers todaycomputers today Many applications require an internet connectionMany applications require an internet connection Now people may have multiple devices that Now people may have multiple devices that

connect to the internet:connect to the internet: LaptopLaptop DesktopDesktop Iphone/BlackberryIphone/Blackberry KindleKindle Ipad/Other tabletsIpad/Other tablets Streaming Video devices (e.g. Roku)Streaming Video devices (e.g. Roku) VoIP (magicjack, comcast voice, etc.)VoIP (magicjack, comcast voice, etc.)

ARPANETARPANET

Early computer networksEarly computer networks Government, government contractors andGovernment, government contractors and

and Academiaand Academia No commercial functionNo commercial function

BBN, August 1962, “Intergalactic BBN, August 1962, “Intergalactic Computer NetworkComputer Network

ARPA RFQ, 1968ARPA RFQ, 1968 4 Nodes, 19694 Nodes, 1969

http://en.wikipedia.org/wiki/File:Arpanet_logical_map,_march_1977.png

D. Mills, Early Internet History and How Urban Legends are Born www.eecis.www.eecis.udeludel.edu/~mills/teaching/eleg867b/history.ppt.edu/~mills/teaching/eleg867b/history.ppt ·  · 1717

ARPANet/MILnet topology circa 1983ARPANet/MILnet topology circa 1983

BRL (Aberdeen) is the predecessorto ARL

How fast are computersHow fast are computers

Measured in instructions/secondMeasured in instructions/second Typical laptop 2.6 Giga-instruction/secondTypical laptop 2.6 Giga-instruction/second Compare to communication speedCompare to communication speed

Light can travel 3*10Light can travel 3*1088(m/s)/10(m/s)/1099(instructions/sec) (instructions/sec) = 0.3 (m/instruction) ~1 ft/instruction= 0.3 (m/instruction) ~1 ft/instruction

Electrical signal moves 1/3 ft/instructionElectrical signal moves 1/3 ft/instruction

If we want fast computers, what must we If we want fast computers, what must we do?do?

SpeedSpeed

Electrical signal travel 2/3eElectrical signal travel 2/3e Electrical signal circles the earth 4-5 Electrical signal circles the earth 4-5

times/secondtimes/second Light circles the earth in 7 times/secondLight circles the earth in 7 times/second

Smaller/faster computersSmaller/faster computers

IssuesIssues HEAT!HEAT! Fast computer are liquid cooled (function Fast computer are liquid cooled (function

similar to a radiator)similar to a radiator)

Next Saturday – www turns 20! Next Saturday – www turns 20!

On August 6, 1991, Tim Berners-Lee posted a short summary of the World Wide Web project on the alt.hypertext newsgroup. This date also marked the debut of the Web as a publicly available service on the Internet. 

Let’s talk about human Let’s talk about human Morse Code Morse Code speed speed ……

http://rogerwendell.com/images/morsecode/morsecode_1939_newspaper.jpg

Transmission RateTransmission Rate

75 words/minutes 75 words/minutes If each word is 5 letters If each word is 5 letters A letter can be represented as a byte (8 A letter can be represented as a byte (8

bits) used ASCII codebits) used ASCII code So McElroy was transmitting at 75 * 5 * 8 So McElroy was transmitting at 75 * 5 * 8

= 1875 bits/minute or 31.25 bits per = 1875 bits/minute or 31.25 bits per secondsecond

Internet connection bandwidthsInternet connection bandwidths

This table shows the maximum bandwidth (the physical layer net bitrate) of common Internet access technologies. http://en.wikipedia.org/wiki/Bandwidth_(computing)

56 kbit/s56 kbit/s Modem / DialupModem / Dialup

1.5 Mbit/s1.5 Mbit/s ADSL Lite

1.544 Mbit/s1.544 Mbit/s T1/DS1

10 Mbit/s10 Mbit/s Ethernet

11 Mbit/s11 Mbit/s Wireless Wireless 802.11b

44.736 Mbit/s44.736 Mbit/s T3/DS3

54 Mbit/s54 Mbit/s Wireless Wireless 802.11g

100 Mbit/s100 Mbit/s Fast EthernetFast Ethernet

155 Mbit/s155 Mbit/s OC3OC3

600 Mbit/s600 Mbit/s Wireless Wireless 802.11n802.11n

622 Mbit/s622 Mbit/s OC12OC12

1 Gbit/s1 Gbit/s Gigabit EthernetGigabit Ethernet

2.5 Gbit/s2.5 Gbit/s OC48OC48

9.6 Gbit/s9.6 Gbit/s OC192OC192

10 Gbit/s10 Gbit/s 10 Gigabit Ethernet10 Gigabit Ethernet

100 Gbit/s100 Gbit/s 100 Gigabit Ethernet100 Gigabit Ethernet

McElroy = 31.25 bits/s

Home internet speed;Home internet speed;

Netflix, for HD content is about 4 to 8 Netflix, for HD content is about 4 to 8 MbpsMbps

Compare >>Compare >> DSL DSL InternetInternet

Cable Cable InternetInternet

Fiber OpticsFiber Optics

Download Download (Min)(Min) 768 Kbps768 Kbps 4 Mbps4 Mbps 10 Mbps10 Mbps

Download Download (Max)(Max) 7.1 Mbps7.1 Mbps 20 Mbps20 Mbps 50 Mbps50 Mbps

Upload (Min)Upload (Min) 128 Kbps128 Kbps 384 Kbps384 Kbps 2 Mbps2 Mbps

Upload (Max)Upload (Max) 768 Kbps768 Kbps 1.5 Mbps1.5 Mbps 20 Mbps20 Mbps

ConnectionConnection Phone LinePhone Line TV CableTV Cable Fiber Optic Fiber Optic LinesLines

Monthly PriceMonthly Price $20 to $45$20 to $45 $40 to $55$40 to $55 $45 to $145$45 to $145

ActivityActivity Build a version of a telegraphBuild a version of a telegraph

Why a light bulb instead of buzzer?Why a light bulb instead of buzzer?

Light Bulb

Morse CodeMorse Code

Dot: Short mark “.” dot is one unit of timeDot: Short mark “.” dot is one unit of time Dash: “-” longer mark 3 times as long as “.”Dash: “-” longer mark 3 times as long as “.” Space between symbols is same length as Space between symbols is same length as

“.”“.” Space between letters is same length as Space between letters is same length as

dashdash Space between words equals 7 dotsSpace between words equals 7 dots

Transmit a Message: Transmit a Message: Isolated ReceiversIsolated Receivers

Group in teams of 4; Pick on person to be the Group in teams of 4; Pick on person to be the sender : sender : No talkingNo talking Each receiver covers their paper and doesn’t share Each receiver covers their paper and doesn’t share

results results

Advice:Advice: Senders make a mistake just continue (sender in DC; Senders make a mistake just continue (sender in DC;

receivers in Baltimore)receivers in Baltimore) Receivers write down the dots and dashes and use a Receivers write down the dots and dashes and use a

vertical line to mark spaces. Decode after msg sent.vertical line to mark spaces. Decode after msg sent.

Transmit a Message: Transmit a Message: Collaborating ReceiversCollaborating Receivers

Group in teams of 4; Pick on person to be the Group in teams of 4; Pick on person to be the sender : sender : Talking among receivers aloudTalking among receivers aloud Receiver can share results Receiver can share results

Advice:Advice: Senders make a mistake just continue (sender in DC; Senders make a mistake just continue (sender in DC;

receivers in Baltimore)receivers in Baltimore) Receivers write down the dots and dashes and use a Receivers write down the dots and dashes and use a

vertical line to mark spaces. Decode after msg sent.vertical line to mark spaces. Decode after msg sent. Try timing sender, how do they compare with Try timing sender, how do they compare with

McElroy?McElroy?

What about ErrorsWhat about Errors

Did you all Did you all receivereceive the same message in the same message in the lab?the lab?

What if you receive the message 2 times?What if you receive the message 2 times? Or 3?Or 3? Do you think you would reduce your Do you think you would reduce your

number of errors?number of errors? Repeating the message is an example of a Repeating the message is an example of a

redundancy code redundancy code

Morse Code on LenoMorse Code on Leno