Digital communication
Lectures
Week 1A
Introduction
Digital; Digitus (Latin); finger
- Numbers are/were counted on fingers
- If something is digital, it can be counted discretely (0,1,2,3,4)
- The simplest digital system is 0 and 1 (on and off)
The opposite of digital is analogue: a number that is continuous (no discrete values/infinity of values)
Analogue: mechanical clock, sound vibrating in the air, record player, film camera, handwriting,
Digital: digital alarm, mp3, cd, digital camera, printed.
Spoken language is both digital (letters, words, sentences) and analogue (volume, pitch, duration).
Digital (electronic) communication:
- Machine with machine
Internet router, USB, WIFI
- Human with human (through a computer)
Whatsapp, twitch, skype
- Human with machine (conversation)
Siri, alexa, customer service hotlines
- Human with interface
Windows user interface, dvd player menu
1) Face-to-face communication
2) Computer-mediated communication
3) Human computer interaction
Week 1B
History of the internet and mediated communication
Information Technology & Effects on human-human communication
Virtual reality, bitcoin and other technologies, we need to know how these things have developed.
Before these technologies, the only ways of sending messages to people was to send a runner, blow
a trumpet or, probably the oldest way to communicate, via slit drums. There were three different
ways people communicated through these drums.
1) Making music together.
Just like how people use music nowadays to communicate emotionally with others
2) Encoding messages with specific patterns.
“Dum-dum-di-dum-dah” = enemy is attacking
❖ This is fully digital communication!
3) Copying the patterns of speech.
Drum beats copy the rhythm, stress and intonation of well-known spoken phrases (functions
as a telephone in a certain extant)
A modern equivalent: speaking piano. It is being used in the same way as the drums; it is mimicking
the sound of the voice.
1
,Communicating via drums:
- Drums are placed strategically
- Sound can be heard 5-10 km
- Each village relays it to the next village → the message is not send from A to B, but is also
relaid by people
- Messages can travel at >100 km/h
One other very important ancient way of transmitting information was the Greek hydraulic
semaphore system.
1) Sender and receiver have the same pots, filled with water, with sticks (with lines on them)
floating with messages written on them.
2) The sender lights up the torch to signal the start.
3) The sender and receiver both let the water run out of the pots.
4) As the water goes down, so do the rods. When the desired message is at the rim of the pot,
the sender signals with the torch to stop letting water out.
5) The receiver looks at the message on the rod.
❖ The messages weren’t sent! They were selected from a pre-existing list! Via the
amount of water and the lines on the sticks, they selected the message from the list.
The first modern communication system that started to look a bit like the internet was the Optical
Telegraphs (semaphore) by Claude Chappe.
- Three linked arms (each can be moved separately):
-middle bar is horizontal or vertical
-both indicator arms could be rotated into 7 positions
→ altogether 2x7x7=98 combinations of position
→ with 26 letters in the alphabet, can transmit more than a latter at a time (each position can be
used to encode words or phrases)
❖ This is fully digital communication!
Messages were encoded before they were transmitted: messages could not be understood, unless
they have the codebook.
Another type of signal: control signals. In addition to the 92 symbols, the signalling system also
needed special control signals. These types of signals are also found in speech, such as: “what?”,
“huh?” and in social media, the blue ticks in WhatsApp.
Although these types of communication were digital, they weren’t electrical. The first electrical
telegraph was the Sommering’s electric telegraph.
- Used 35 wires to represent all the Latin letters
- The sender passes an electric current through the wire for each letter
- The receiver reads what letter is sent by seeing where the bubbles form in the tower
- Could transmit messages up to 4 km
Samuel Morse decided to try and invent a way to communicate over long distances: morse code. A
morse key produces dots and dashes. It was successful because of its simplicity: only two cables
needed.
❖ This is fully digital communication! (key pressed vs. key released)
The general principle behind it is still used at the moment: the common letters were shortest in use
of dots and dashes → the code tree: the most common letters are higher up, the least common ones
are down. (e, t, a, i and n are the five most frequent letters in English texts)
The same principle is used in ZIP files (Huffman coding). The ZIP files contains all the most common
sequences of bits/sequences of 0’s and 1’s and it encodes them.
2
,The first commercial telegraph was build between Washington D.C. and Baltimore (61 km). They
started laying down cables: transatlantic cable. Within 20 years, the British empire laid cables all
around the world: the Victorian “Internet” → telegraph networks.
The average person couldn’t type morse code → a telegraph operating room: receives telegraph
messages and write it on a card, which was send to a delivery person, who send it to a house → the
first “instant messaging”.
The first “instant messaging”: when telegraph operators weren’t busy sending messages for other
people, they would have long conversations with the other operators, thousands of miles away (the
first viral jokes).
Even though morse code is digital (on-off/dot-dash), experiences telegraph operators could
recognize the other person’s gender and regional accents and recognize each other’s individual
patterns.
Today’s text messaging is ‘ruining’ the language, because of the abbreviations (gr8), but even with
morse code these abbreviations were used (laughter was shown by typing “ha”).
The telegraph transformed society: it enabled the sending of ‘time-sensitive’ information.
The morse key became smaller and smaller and gave rise to the invention telephone. The system
went from digital (dot/dash, on/off) to analogue. To communicate via telephone, the inventors
created a new convention: ‘hello’.
The inventor (Alexander Graham Bell) believed the phone would mainly be a busines tool with the
line permanently open. To get the attention of the other person you would need to notify the other
person with ‘hello’.
(alexander proposed Ahoy, Thomas Edison proposed Hello)
This shows that language emerges out of technology → the first telephone directory: instructions for
a telephone talk (identify yourself, apologize for wrong numbers).
Within ten years of the telephone being invented, there was the first (known) prank phone call.
The telephone also provided the first “streaming” of music. In cities throughout the world, phone
companies place telephone microphones in concert halls + theatres. Some were coin-operated, some
also gave news updates and people could subscribe at home. People actually thought that this was
what the telephone was for.
People’s telephones were connected to human operators who connected you to the other person →
the invention of automatic switching (Almon Strowger). He wanted to solve deliberate human error.
He also solved:
- Unintended human errors
- Speed of making a connection
- Direct dialling
- Lowering the costs of running a local exchange
- Laid the foundation for the automatic switching of the internet
A jump to the internet
3
, Russia launched the first satellite “Sputnik”. The US was very concerned this could be used as a
weapon and created a special agency – Advanced Research Projects Agency (ARPA). Their task was to
create a military communication network.
- Decentralized: that still works if parts of it are destroyed
- Should be able to survive nuclear attack
→ network with many parallel connections (difficult to destroy all of them) → ARPAnet consisted of
four interconnected computers at different universities: UCLA (Los Angeles), UCSB (Santa Barbara),
SRI (Stanford), Utah State University. Eventually, the ARPAnet grows and grows: emergence of
networks in different parts of the country, which are connected to each other. (these are all still
wires)
Back in the days, you could only send a message to someone if they were on the same computer →
solution by S.R. Tomlinson: use the @ sign to separate the user from the machine.
Eventually, the ARPAnet goes international. At this point email accounted for 75% of all ARPAnet
network traffic. The ARPAnet grows: more connections between and inside the networks (centres).
Originally, the ARPAnet was controlled by the military. They handed it over to the government and
private companies for control. The military continued to develop their own network, separate from
the internet. Internet was reorganized as a decentralized “network of networks”: communicating
using a shared standard. Internet is connecting networks to each other.
There are three main types of networks: centralised (from one centre), decentralised (from several
centres) and distributed (there is not centre).
If parts of the internet are destroyed, the internet adapts by sending it via a different route. It is not
choosing the shortest path (they don’t know the shortest path), they just know who to send it on
next.
The first internet chat was internet relay chat (IRC). Time Berners-Lee proposed hypertext: a
document that contains links to other documents (invention of the world-wide-web) → hypertext
transfer protocol (http): how a client and server communicate with each other to download text,
images, movies, etc.).
The first webcam was invented so that Computer Scientists at Cambridge University could see
whether the coffee pot was full or not from different rooms.
The first browser was Lynx → the first browsers with images was Mosaic → (1997-2001) internet
bubble and crash: before the crash web 1.0, after the crash web 2.0.
- Web 1.0: connecting people to programs
User → the internet → online shopping, online news, online travel agents, etc.
- Web 2.0: internet is about connecting people to each other
Software should connect people + emphasize online collaboration, discussion, sharing and
generation of content. (many sites added discussion/collaboration functionality as they
evolved)
❖ Communication is central!
99% of internet traffic is underwater (via internet cables), other via satellite
4
Lectures
Week 1A
Introduction
Digital; Digitus (Latin); finger
- Numbers are/were counted on fingers
- If something is digital, it can be counted discretely (0,1,2,3,4)
- The simplest digital system is 0 and 1 (on and off)
The opposite of digital is analogue: a number that is continuous (no discrete values/infinity of values)
Analogue: mechanical clock, sound vibrating in the air, record player, film camera, handwriting,
Digital: digital alarm, mp3, cd, digital camera, printed.
Spoken language is both digital (letters, words, sentences) and analogue (volume, pitch, duration).
Digital (electronic) communication:
- Machine with machine
Internet router, USB, WIFI
- Human with human (through a computer)
Whatsapp, twitch, skype
- Human with machine (conversation)
Siri, alexa, customer service hotlines
- Human with interface
Windows user interface, dvd player menu
1) Face-to-face communication
2) Computer-mediated communication
3) Human computer interaction
Week 1B
History of the internet and mediated communication
Information Technology & Effects on human-human communication
Virtual reality, bitcoin and other technologies, we need to know how these things have developed.
Before these technologies, the only ways of sending messages to people was to send a runner, blow
a trumpet or, probably the oldest way to communicate, via slit drums. There were three different
ways people communicated through these drums.
1) Making music together.
Just like how people use music nowadays to communicate emotionally with others
2) Encoding messages with specific patterns.
“Dum-dum-di-dum-dah” = enemy is attacking
❖ This is fully digital communication!
3) Copying the patterns of speech.
Drum beats copy the rhythm, stress and intonation of well-known spoken phrases (functions
as a telephone in a certain extant)
A modern equivalent: speaking piano. It is being used in the same way as the drums; it is mimicking
the sound of the voice.
1
,Communicating via drums:
- Drums are placed strategically
- Sound can be heard 5-10 km
- Each village relays it to the next village → the message is not send from A to B, but is also
relaid by people
- Messages can travel at >100 km/h
One other very important ancient way of transmitting information was the Greek hydraulic
semaphore system.
1) Sender and receiver have the same pots, filled with water, with sticks (with lines on them)
floating with messages written on them.
2) The sender lights up the torch to signal the start.
3) The sender and receiver both let the water run out of the pots.
4) As the water goes down, so do the rods. When the desired message is at the rim of the pot,
the sender signals with the torch to stop letting water out.
5) The receiver looks at the message on the rod.
❖ The messages weren’t sent! They were selected from a pre-existing list! Via the
amount of water and the lines on the sticks, they selected the message from the list.
The first modern communication system that started to look a bit like the internet was the Optical
Telegraphs (semaphore) by Claude Chappe.
- Three linked arms (each can be moved separately):
-middle bar is horizontal or vertical
-both indicator arms could be rotated into 7 positions
→ altogether 2x7x7=98 combinations of position
→ with 26 letters in the alphabet, can transmit more than a latter at a time (each position can be
used to encode words or phrases)
❖ This is fully digital communication!
Messages were encoded before they were transmitted: messages could not be understood, unless
they have the codebook.
Another type of signal: control signals. In addition to the 92 symbols, the signalling system also
needed special control signals. These types of signals are also found in speech, such as: “what?”,
“huh?” and in social media, the blue ticks in WhatsApp.
Although these types of communication were digital, they weren’t electrical. The first electrical
telegraph was the Sommering’s electric telegraph.
- Used 35 wires to represent all the Latin letters
- The sender passes an electric current through the wire for each letter
- The receiver reads what letter is sent by seeing where the bubbles form in the tower
- Could transmit messages up to 4 km
Samuel Morse decided to try and invent a way to communicate over long distances: morse code. A
morse key produces dots and dashes. It was successful because of its simplicity: only two cables
needed.
❖ This is fully digital communication! (key pressed vs. key released)
The general principle behind it is still used at the moment: the common letters were shortest in use
of dots and dashes → the code tree: the most common letters are higher up, the least common ones
are down. (e, t, a, i and n are the five most frequent letters in English texts)
The same principle is used in ZIP files (Huffman coding). The ZIP files contains all the most common
sequences of bits/sequences of 0’s and 1’s and it encodes them.
2
,The first commercial telegraph was build between Washington D.C. and Baltimore (61 km). They
started laying down cables: transatlantic cable. Within 20 years, the British empire laid cables all
around the world: the Victorian “Internet” → telegraph networks.
The average person couldn’t type morse code → a telegraph operating room: receives telegraph
messages and write it on a card, which was send to a delivery person, who send it to a house → the
first “instant messaging”.
The first “instant messaging”: when telegraph operators weren’t busy sending messages for other
people, they would have long conversations with the other operators, thousands of miles away (the
first viral jokes).
Even though morse code is digital (on-off/dot-dash), experiences telegraph operators could
recognize the other person’s gender and regional accents and recognize each other’s individual
patterns.
Today’s text messaging is ‘ruining’ the language, because of the abbreviations (gr8), but even with
morse code these abbreviations were used (laughter was shown by typing “ha”).
The telegraph transformed society: it enabled the sending of ‘time-sensitive’ information.
The morse key became smaller and smaller and gave rise to the invention telephone. The system
went from digital (dot/dash, on/off) to analogue. To communicate via telephone, the inventors
created a new convention: ‘hello’.
The inventor (Alexander Graham Bell) believed the phone would mainly be a busines tool with the
line permanently open. To get the attention of the other person you would need to notify the other
person with ‘hello’.
(alexander proposed Ahoy, Thomas Edison proposed Hello)
This shows that language emerges out of technology → the first telephone directory: instructions for
a telephone talk (identify yourself, apologize for wrong numbers).
Within ten years of the telephone being invented, there was the first (known) prank phone call.
The telephone also provided the first “streaming” of music. In cities throughout the world, phone
companies place telephone microphones in concert halls + theatres. Some were coin-operated, some
also gave news updates and people could subscribe at home. People actually thought that this was
what the telephone was for.
People’s telephones were connected to human operators who connected you to the other person →
the invention of automatic switching (Almon Strowger). He wanted to solve deliberate human error.
He also solved:
- Unintended human errors
- Speed of making a connection
- Direct dialling
- Lowering the costs of running a local exchange
- Laid the foundation for the automatic switching of the internet
A jump to the internet
3
, Russia launched the first satellite “Sputnik”. The US was very concerned this could be used as a
weapon and created a special agency – Advanced Research Projects Agency (ARPA). Their task was to
create a military communication network.
- Decentralized: that still works if parts of it are destroyed
- Should be able to survive nuclear attack
→ network with many parallel connections (difficult to destroy all of them) → ARPAnet consisted of
four interconnected computers at different universities: UCLA (Los Angeles), UCSB (Santa Barbara),
SRI (Stanford), Utah State University. Eventually, the ARPAnet grows and grows: emergence of
networks in different parts of the country, which are connected to each other. (these are all still
wires)
Back in the days, you could only send a message to someone if they were on the same computer →
solution by S.R. Tomlinson: use the @ sign to separate the user from the machine.
Eventually, the ARPAnet goes international. At this point email accounted for 75% of all ARPAnet
network traffic. The ARPAnet grows: more connections between and inside the networks (centres).
Originally, the ARPAnet was controlled by the military. They handed it over to the government and
private companies for control. The military continued to develop their own network, separate from
the internet. Internet was reorganized as a decentralized “network of networks”: communicating
using a shared standard. Internet is connecting networks to each other.
There are three main types of networks: centralised (from one centre), decentralised (from several
centres) and distributed (there is not centre).
If parts of the internet are destroyed, the internet adapts by sending it via a different route. It is not
choosing the shortest path (they don’t know the shortest path), they just know who to send it on
next.
The first internet chat was internet relay chat (IRC). Time Berners-Lee proposed hypertext: a
document that contains links to other documents (invention of the world-wide-web) → hypertext
transfer protocol (http): how a client and server communicate with each other to download text,
images, movies, etc.).
The first webcam was invented so that Computer Scientists at Cambridge University could see
whether the coffee pot was full or not from different rooms.
The first browser was Lynx → the first browsers with images was Mosaic → (1997-2001) internet
bubble and crash: before the crash web 1.0, after the crash web 2.0.
- Web 1.0: connecting people to programs
User → the internet → online shopping, online news, online travel agents, etc.
- Web 2.0: internet is about connecting people to each other
Software should connect people + emphasize online collaboration, discussion, sharing and
generation of content. (many sites added discussion/collaboration functionality as they
evolved)
❖ Communication is central!
99% of internet traffic is underwater (via internet cables), other via satellite
4
