History of Communications:
1450 Johannes Gutenberg builds the movable printing
1826 Joseph Niepce of produces the wrold’s first
permanent photographic image.
1876-Alexander Graham Bell introduced telephone.
1877 Thomas Edison patents the phonograph.
1891 Thomas Edison and William Dickson invent the
1895 Guglielmo Marconi develops the wireless
1925 John Logie Baird transmits the first television
1954 The transister radio or tubeless radios become
available in the USA
1990 The world wide web is created in Europe. It’s
chief architect is Tim Berners-Lee.
Communication is the ability to send and
People to people
People to machine
Machine to people
Machine to machine
Messages are intended to:
Inform – news papers, TV news casts
Educate – texts, video, DVD’s, internet.
Persuade - advertising
Control – machines and tools such as Computer
Numeric Control: A type of programmable
control system, directed by mathematical
data, which uses microcomputers to carry
out various machining operations; such as a
mill or lathe.
CNC Milling Video
An example of communications used to
control is traffic signals and sensors that are
used to send messages to the traffic signals.
All communication systems include a
message, a sender, a communication
channel, and a receiver.
A communication channel is the path over
which a message must travel to get from the
sender to the receiver.
Like all systems, communication systems
follow the universal systems model.
Tools and machines
Positive Outputs – The desired result of the system.
Negative Outputs – The unwanted results created by the
Pollution - Old phones, computers, devices, etc.
Your response to communications
Telecommunications means communicating
over a long distance.
The telegraph by Samuel Morse.
Sent electronic signals using wires.
Morse devised a language with a series of
long and short signals that represented
letters and numbers.
Video: Telegraph Machine
The Telephone by Alexander Graham Bell
Video: Digital vs. Analog
Copper Wire: Many older phones
consist of two thin insulated copper
wires twisted around each other.
Coaxial Cable: Carry many more
messages all at once than twisted-
pair wire. Consists of an outer tube
made of a material that conducts
electricity (usually copper). Inside the
tube is an insulated central conductor
(also copper). Several of these cables
are combined into one bundle.
Optical Fibers: thin
fibers of pure glass that
carry signals in the
form of pulses of light.
Each optical fiber is
surrounded by a
reflective cladding and
an outside protective
coating. The light
pulses are converted to
Microwaves can be used to carry phone
conversations over long distances. Microwaves are
very short electromagnetic waves that travel
through the atmosphere and make communication
without connecting wires possible.
In cell phones, sound waves are changed into
microwaves. They are transmitted using an
antenna (sent and received) and converted back to
Video: How Television Works
Satellite Communication Systems
A communication satellite is a device placed
into orbit above earth to receive messages
from one location and transmit them to
It reflects signals back to earth like a mirror.
SES Global Video