ALE 221
TELECOMMUNICATION SYSTEMS
(from Mechanical and electrical systems in architecture, engineering, and construction (5th Edition) by Joseph B. Wujek & Frank R.
Dagostino)
Report by Bezyl Casol
INTRODUCTION
Telecommunication is the exchange of information through electromagnetic
systems such as radio, wire, optical, and other signs, writes, words, messages,
sounds, and images. When users use technology to exchange information with one
another, that is telecommunication. It sustains our civilization and has contributed to
the creation of a global village, with 98 percent of the globe covered by its network.
Every aspect of life has been affected by the necessity of communication, some of
which we will discover right away.
In this module, you will learn about the history and fundamentals of
telecommunication systems, telecommunications networks, types of transmission
media, and electromagnetic interference.
HISTORICAL PERSPECTIVE
Over many centuries, methods for communication across
great distances have developed. Despite the fact that carrier
pigeons were initially used to transmit messages about 700
B.C.E., the first long-distance communication devices were
based on sound and light signals
such as drums and horns, smoke
signals and beacon fires. In 1588
C.E., signal fires informed the
British of the Spanish Armada's
arrival.
In 1793, Claude Chappe created an optical
telegraph (semaphore) system of stations built on
rooftops that could be seen from a long distance. A
column-like tower with a moveable beam and two
moveable arms made up each semaphore station. Ropes
allowed the beam and arms to swivel while sending
various signal patterns that represented upper- and
lowercase letters, punctuation, and numbers. An observer
at another station translated the patterns into words and
forwarded it onto the following station. As long as visibility
was good, this technology permitted the French to send a
brief message over 100 miles (160 km) in less than 5
minutes. Abraham Niclas Edelcrantz developed another
type of optical telegraph system with ten collapsible iron shutters.
Only with the demonstration of
electromagnetism by Christian Oersted
in 1820 and electrical flow by Michael
Faraday and others before him did
communications by passing electrical
impulses through wires become a
reality. Joseph Henry created the first usable electrical signal in 1830 when he used
electromagnetic signals to ring a bell by passing energy through a long network of
wires. The electric telegraph, with its system of electrical impulses labeled as dots and
dashes that eventually came to be known as Morse Code, was the first working
electrical communication device Samuel Morse patented in 1831.
Electrical Telegraph
Morse Code
On May 24, 1844, the Supreme Court Room in the US Capitol sent the first
electric telegraph message, "What hath God wrought," to the railway depot in
Baltimore. Three decades later, in 1861, the East and West coasts were connected,
and there were over 2000 telegraph offices operating throughout America. The first
transatlantic cable between England and the United States was built six years later.
On March 10, 1876, Alexander Graham Bell
invented the telephone. “Mr. Watson, come here, I
want you!” were the first words accidentally spoken
into the new invention. The first telephone company,
American Bell, was established four years later in
1880, and by that time there were over 30 000 phones
in service. Over ten million telephones from the
American Bell System were in use around 1920.
Gugliemo Marconi demonstrated the first radio
transmission in 1895. Six years later, in
Newfoundland, Canada, Marconi's radio picked up a
weak signal that had been transmitted from one of his
colleagues in Cornwall, England, across the Atlantic
Ocean. The signal, a Morse Code "S" delivered as
"dot, dot, dot," proved that radio waves could bounce
off of the upper atmosphere. A year later, the first
authentic radio message was transmitted. Using radio waves to carry signals,
transatlantic communications between New York and London were operational less
than 50 years after the invention of the telephone.
In 1865, the first commercial fax system was created by Giovanni
Caselli as a pantelegraph for the transmission of photographs. The first
public demonstration of picture transmission through
telephone wires took place on May 19, 1924. John
Logie Baird delivered the first public presentation of a
mechanical television on January 23, 1926, which
featured actual human features rather than merely
silhouettes or outlines. With this application of radio
waves, visual transmission made a significant
advancement toward the television we use today.
FUNDAMENTALS OF TELECOMMUNICATION SYSTEMS
Telecommunication is the act of transmitting, emitting, or receiving any kind of
letter, sign, signal, sound, image, or information over a
wire, radio, optical, or other electromagnetic system.
A telecommunication system transmits signals that
carry voice and data communications via electricity,
visible and infrared light, or radio waves.
Telecommunication
systems
work
by
converting sound waves or data into signals that then
travel via wires or through the air to their intended
location. The signals are converted back into usable
data or sound waves when a receiver intercepts them,
making them audible to humans and recognizable to
brains. A transceiver is a transmitter and receiver in a telecommunications system.
Analog transmission has traditionally been utilized in telecommunications
systems like telephone systems. In an electronic network, analog transmission is the
transformation of useful sound or data into electrical impulses. Both voice and
nonvoice communications can be transmitted through it (e.g., telex, telegrams, data).
However, nonvoice signals cannot be
transferred quickly since they are bulky
when transmitted in analog format.
Today's systems make advantage of
digital transmission technology. In an
electronic
network,
digital
transmission includes sending a
signal that changes in voltage to
represent one of two distinct states
(e.g., on and off or 0 and 1). In an optical network, digital signaling may take the form of
either pulsing (on and off) light or a change in the light signal's intensity. By changing
the wave's amplitude, digital data can be transmitted across radio networks
(microwave, cellular, or satellite). A quick way to transmit voice and nonvoice data is
provided by digital transmission technology.
The span between the highest and lowest transmission
frequencies in telecommunications networks is known as the
bandwidth and is expressed in hertz (Hz), or cycles per second. The
kind and mode of transmission affect bandwidth. It serves as a
measure of informational capacity.
TELECOMMUNICATIONS NETWORK
A group of interconnected communication tools and devices is known as a
telecommunications network. To transfer data, hardware, and software, or to carry
out an electronic task, two parties must communicate. The network consists of a
number of nodes, or connecting points, that are connected by cables and comprise, for
example, telephone receivers and computers (wiring). Additionally, networks contain
subnetworks and can connect to other networks.
The term "topology" refers to
the configuration of a network,
including its nodes, connecting cables,
and equipment, in terms of design and
architecture
of
communication
networks. It describes how the
network's workstations are connected
to one another by cable. The bus,
star, and ring are the three basic
network topologies.
Each workstation (node) is linked to a single cable trunk
using a bus topology. All signals are disseminated to every
workstation. As the signal travels down the bus, each computer
examines the address on the signal. The computer processes
the signal if its address matches to that of the signal. If the
addresses do not match, the computer does nothing and the
signal passes to the following computer on the bus.
All workstations (nodes) in a star
topology are linked to a hub, which is a central
component. Home runs are cables that reach
directly from the hub to the termination with no
extra connections or splicing. With this setup,
cables can be connected directly between
workstation
equipment
(e.g.,
computers,
printers, telephone receiver, and so on),
telecommunications closet equipment, and
entrance facilities/equipment room equipment.
The devices and workstation equipment connected by a
network with a ring topology are connected point-to-point
serially in an unbroken circular configuration.
Local area networks (LAN), metropolitan area networks (MAW), and wide area
networks (WAN) are three types of networks that can be
differentiated based on the spatial distance between
their nodes. In order to construct big WANs, huge
telephone networks and networks that use their
infrastructure, like the Internet, have sharing and
exchange agreements
with other businesses. WANs enable localized
networks to connect with one another across great
distances because they are not restricted to a
particular location. LANs are employed for
constructing telecommunications systems. LANs link
computers and hardware, including printers, that are
placed close to one another and share materials,
tools, and files. A metropolitan area network (MAN)
is a type of computer network that is bigger than a LAN for a single building but smaller
than a wide area network because it is restricted to a single geographic area.
TRANSMISSION MEDIA
The most typical method for transferring voice and
data between network devices is cable. It acts as a
telecommunications system's pipeline. Copper wire,
coaxial cable, and optical fibers are just a few of the
several kinds of cables that are in use.
The devices known as connectors are what link a
cable to a network device. Connectors might be included
with the equipment you bought, or you might need to buy
them separately. The weakest part of any network is
usually the connection, so it is important to make them
properly.
Types of Transmission media
➔ Copper Wiring
Historically, the primary telecommunications transmission medium has been
copper wiring. It is made up of a pair or more of solid copper wires.
❖ Twisted Pair Cable
Copper wire pairs that have been twisted to particular specifications make up
twisted pair cable. To help reduce interference from adjacent pairs and other electrical
equipment, each pair is twisted with a specific number of twists per inch; the tighter the
twisting, the higher the supported transmission rate, but the higher the cost.
●
Shielded and unshielded Twisted Pair Cable
Shielded and unshielded variants of twisted pair wiring are both available.
Multiple pairs of twisted, insulated copper conductors that
are joined together in a single sheath make up unshielded
twisted pair (UTP) wiring. It is susceptible to electrical
interference since it is not protected from electromagnetic
waves . For simple phone, fax, or data connections, UTP
wiring is sufficient.
Shielded twisted pair wire (STP) is a type of wiring
for specific purposes that is enclosed in a shield. The
standard twisted pair wires are given an additional
outside covering, or shield, which serves as a ground.
Electrically noisy locations are suited for STP, however
the additional shielding can make the cables rather
clumsy.
American Wire Gauge (AWG) is the U.S.
standard for wire conductor size used in copper
electrical power and telephone lines. The gauge
describes wire thickness: the thinner the wire, the
higher the gauge number. AWG 14 or 12 wire is
typically used for wiring in domestic power circuits, with
larger gauges utilized for circuits servicing heavy
equipment. The AWG of telecommunications wire is
commonly 22, 24, or 26.
The typical female connectors for UTP cable in a
telecommunications system are RJ45 connectors. Registered jack,
or RJ, denotes that the connector adheres to a standard that was
taken from the phone sector. There are certain business telephones
that employ the eight-pin RJ45 connector for data transmission or
networking.
➔ Coaxial Cable
An inner solid wire and an outside, braided
metal sheath make up the two conductors of
coaxial cable. The term "coaxial" comes from the
fact that both conductors run concentrically along the same axis (COAX). Coaxial
cables can be bundled together and shielded by an outer covering known as a jacket.
Primary Types of Coaxial Cable
❖ Thin coaxial cable
Thin coaxial cable is also referred to as thinnet. Thinnet is about 1 ⁄4 inch
(8 mm) in diameter and is very flexible. It looks like a regular TV cable. The
10Base2 designation refers to specifications for thin coaxial cable. The 2 refers
to the approximate maximum segment length being 200 m (654 ft), but the
maximum practical segment length is actually 185 m (605 ft).
❖ Thick coaxial cable
Thick coaxial cable is referred to as thicknet. 10Base5 refers to the
specifications for thick coaxial cable. The 5 refers to the maximum segment
length being 500 m (1635 ft). Thick coaxial cable has an extra protective plastic
cover that helps keep moisture away from the center conductor. This makes
thick coaxial a better choice when running longer lengths in a linear network. A
disadvantage of thick coaxial is that it does not bend easily and is difficult to
install. Thicknet is not commonly used except as a backbone within and
between buildings.
❖ Triax cable
Triax cable is a type of coax cable with an additional outer copper braid
insulated from signal carrying conductors. It has a core conductor and two
concentric conductive shields.
❖ Twin axial cable (Twinax)
Twin axial cable (Twinax) is a type of communication transmission cable
consisting of two center conductors surrounded by an insulating spacer, which in
turn is surrounded by a tubular outer conductor (usually a braid, foil, or both).
The entire assembly is then covered with an insulating and protective outer
layer. It is similar to coaxial cable except that there are two conductors at the
center.
Advantage of Coaxial Cable
Coaxial cable is very effective at carrying many analog signals at high
frequencies. In contrast to twisted pair wires, coaxial has a much higher
bandwidth to carry more data, and offers greater protection from noise and
interference. Although coaxial cabling is difficult to install, it is highly resistant to
signal interference. In addition, it can support greater cable lengths between
network devices than twisted pair copper cable.
The Bayonet Neil-Concelman (BNC) connector is the most typical type of
connector used with coaxial cables. The primary conducting (core) wire is connected to
a pin on a BNC male connector, which is then held in place by an outer ring that rotates
into a locked position.
➔ Optical Fibers
Optical fibers are long, thin, hair-like strands
of extremely pure silicon glass or plastic. Three
components make up a single optical fiber: a core,
which is a thin glass section in the middle of the fiber
through which light travels; a cladding, which is an
outer layer that reflects light back into the core; and
a buffer coating, which is a plastic covering that
shields the fiber from harm and moisture.
Optical cables are collections of hundreds or
thousands of optical fibers. These bundles are
shielded by the jacket, which is the cable's outer covering. Single-mode fibers, which
transmit one signal per fiber (used in telephones and cable TV), and multimode
fibers, which transmit numerous signals per fiber (used in computer networks, local
area networks), are the two different types of optical fibers.
The ST and SC connections are the ones used with fiber optic cable the
most frequently. Similar to a BNC connector in shape, the ST connector
is cylindrical. The SC connector is simpler to attach in a small place
because of its squared face.
Copper cable cannot carry nearly as much information as optical fiber,
which is also often immune to electromagnetic interference. It is therefore perfect for
settings with a lot of electrical interference. Its conventional status as a transmission
medium for networks linking between buildings is a result of this property.
Fiber optics refers to the technology in which
communication signals in the form of modulated light beams
are transmitted over a glass fiber transmission medium.
A fiber optic relay system transmits and receives a light signal that is
transmitted through an optical fiber. An optical transmitter produces and encodes the
light signal that is sent through the
optical fiber. An optical receiver that
decodes the signal receives the light
signal. The receiver uses a photocell
or photodiode to detect the light signal,
decodes it, and sends an electrical
signal to a computer, TV, or telephone.
Over long distances, an optical
regenerator is needed to boost the
light signal. One or more optical regenerators may be spliced along a long cable to
amplify the degraded light signal.
Fiber optic cable has the ability to transmit signals over much longer distances
than coaxial and twisted pair cabling and can carry information at much greater
speeds. This capacity broadens communication possibilities to include services such
as video conferencing and interactive services. The cost of fiber optic cabling is
comparable to copper cabling; however, it is more difficult to install and modify.
➔ Wireless
Wireless is a term used to describe telecommunications in which
electromagnetic waves (instead of some form of wire) carry the signal. Wireless
communications can take several forms: microwave, synchronous satellites,
low-earth-orbit satellites, cellular, and personal communications service (PCS).
Fixed wireless is the operation of wireless devices or systems in homes and
offices, and in particular, equipment connected to the Internet by the use of specialized
modems. A fixed wireless network enables users to establish and maintain a wireless
connection throughout or between buildings, without the limitations of wires or cables.
The two types of wireless networks are peer-to-peer and access point or base
station. A peer-to-peer wireless network wavelength consists of a number of
computers, each equipped with a wireless
networking interface card. Each computer can
communicate directly with all of the other
wireless-enabled computers and equipment
(e.g., printers).
An access point or base station wireless network has a computer or receiver
that serves as the point at which the network is accessed. It acts like a hub, which
provides connectivity for the wireless equipment.
Two modes of transmission are used in fixed wireless
systems in buildings: infrared and radio frequency. Infrared (IR)
wireless is the use of technology in devices or systems that
convey data through infrared radiation.
Radio
frequency
(RF)
wireless
transmits data through radio wavelengths.
Infrared radiation is electromagnetic energy at
wavelengths somewhat longer than those of
visible red light. Radio wavelengths are much
longer than infrared wavelengths. Both infrared
and radio wavelengths are invisible to the
unaided eye.
Wi-Fi (derived from the term wireless fidelity) is the popular expression
used to describe high-frequency wireless local area network (WLAN)
technology. Wireless hotspots provide Internet access using wireless
network devices installed in public locations. Wi-Fi technology can be
used at home where a computer can be connected to the Internet
anywhere in the home without being wired. As a result, Wi-Fi is the
pre-eminent technology for building general purpose wireless networks.
Electromagnetic Interference
A telecommunication cable placed within an electromagnetic field will have its
telecommunication signal affected. This is known as electromagnetic interference.
Because of potential for electromagnetic interference, voice and data
telecommunications cabling should not be run adjacent and parallel to power
(electrical) cabling unless the cables are shielded and grounded. For low-voltage
telecommunication cables, a minimum 5-in (125 mm) distance is needed from any
fluorescent lighting fixture or power line over 2000 volt-amperes (VA) and up to 24 in
from any power line over 5000 VA. In general, telecommunications cabling is routed
separately or several feet away from power cabling. For similar reasons,
telecommunications cabling must be routed away from electrical equipment.
The table below contains the acronyms and abbreviations used in the
telecommunications industry.
CONCLUSION
In conclusion, telecommunication is vital in the lives of humans, especially in this
technologically advanced world. Since the start of the twenty-first century,
telecommunication has been a movement that cannot be stopped. Taking advantage of
these technological advancements is better for everyone, including businesses.
Furthermore, individuals might expect wireless communications worldwide as
technology develops. The world can become much more efficient due to the many
advantages of wireless communications. However, just like every recent development
in the modern world, there are certain worries. A few problems prevent wireless
technology from progressing, such as security concerns about access to a person's
personal information or the perceived detrimental effects on society. The issues with
wireless communications can be lessened and made to play a bigger role in the globe
with more research and trials.
References
Wujek, J. B., & Dagostino, F. R. (2010). Mechanical and electrical systems in
architecture, engineering, and construction (5th ed.). Prentice Hall.