2. INTRODUCTION:
• Telecommunications, or telecom, is the transmission of signals
over long distances.
• It began with the invention of the telegraph in 1837, followed
by the telephone in 1876.
• Radio broadcasts began the late 1800s and the first television
broadcasts started in the early 1900s. Today, popular forms of
telecommunications include the Internet and cellular phone
networks.
• Early telecommunications transmissions used analog signals,
which were transferred over copper wires. Today, telephone
and cable companies still use these same lines, though most
transmissions are now digital.
3. Definition of telecommunication
• Telecommunication is communication at a
distance by technological means, particularly
through electrical signals or electromagnetic
waves.
4. Basics of telecommunication
• A wave can be described as a disturbance that
travels through a medium from one location
to another location.
• Waves transfer energy from one point to
another without transferring matter.
• They consist of disturbances which transfer
the energy in the direction the wave travels
without transferring matter.
5. Definition of waves
• Waves are disturbances which propagate (move)
through a medium, Light is a special case, it exhibits
wave-like properties but does not require a medium
through which to Propagate. Waves occur frequently
in nature. The most obvious examples are waves in
water, on a dam, in the ocean, or in a bucket.
6. Characteristics of Waves:
I. Amplitude
II. Wavelength
III. Wave frequency
IV. Wave velocity
V. Interference of Waves
VI. Destructive interference
7. I. Amplitude
• The characteristic height of a peak and depth of a
trough is called the amplitude of the wave. The
vertical distance between the bottom of the
trough and the top of the peak is twice the
amplitude. We use symbols agreed upon by
convention to label the characteristic quantities
of the waves. Normally the letter A is used for the
amplitude of a wave.
• The units of amplitude are meters (m)
Conti…
9. II Wavelength
• The distance between two adjacent (next to each
other) peaks is the same no matter which two
adjacent peaks . So there is a fixed distance between
the peaks.
• Looking closer you'll notice that the distance
between two adjacent troughs is the same no matter
which two troughs you look at. But, more
importantly, it is the same as the distance between
the peaks. This distance which is a characteristic of
the wave is called the wavelength.
• Waves have a characteristic wavelength. The units
are meters (m).
conti…
11. III Wave frequency
• frequency definition. In physics, the number of
crests of a wave that move past a given point in a
given unit of time. The most common unit of
frequency is the hertz (Hz), corresponding to one
crest per second.
• The frequency of a wave can be calculated by
dividing the speed of the wave by the
wavelength. wave velocity, distance traversed by
a periodic, or cyclic, motion per unit time (in any
direction).
Conti…
13. IV. Wave velocity
• Wave velocity in common usage refers to
speed, although, properly, velocity implies
both speed and direction. The velocity of a
wave is equal to the product of its wavelength
and frequency (number of vibrations per
second) and is independent of its intensity
14. V. Interference of Waves
• Wave interference is the phenomenon that
occurs when two waves meet while traveling
along the same medium. The interference of
waves causes the medium to take on a shape
that results from the net effect of the two
individual waves upon the particles of the ms
Conti…
16. VI Destructive interference
• Destructive interference occurs when waves
come together in such a way that they completely
cancel each other out. When two waves interfere
destructively, they must have the same amplitude
in opposite directions.
• In general, whenever a number of waves come
together the interference will not be completely
constructive or completely destructive, but
somewhere in between. It usually requires just
the right conditions to get interference that is
completely constructive or completely
destructive.
18. Types of Waves :
a) Transverse wave :
b) longitudinal wave:
c) Electromagnetic wave :
d) Mechanical wave :
19. a) Transverse wave
• A transverse wave is a wave in which particles of
the medium move in a direction perpendicular to
the direction that the wave moves.
• A wave motion, in which the particles of the
medium oscillate about their mean positions at
right angles to the direction of propagation of the
wave, is called transverse wave.
• These waves can propagate through solids and
liquids but not through gases, because gases do
not possess elastic properties. Examples of these
waves are: vibrations in strings, ripples on water
surface and electromagnetic waves.
21. b) longitudinal wave
• A longitudinal wave is a wave in which particles of
the medium move in a direction parallel to the
direction that the wave moves.
• A Longitudinal wave proceeds in the form of
compression and rarefaction which is the
stretched rubber band. For a longitudinal wave at
places of compression the pressure and density
tends to be maximum, while at places where
rarefaction takes place, the pressure and density
are minimum.
• Longitudinal waves are known as Compression
waves.
Conti…
23. b) longitudinal wave
• Examples of longitudinal waves : Sound waves,
tsunami waves, earthquake ,P - waves, ultra
sounds, vibrations in gas, and oscillations in
spring, internal water waves.
• Electromagnetic versus Mechanical Waves
• Another way to categorize waves is on the basis
of their ability or inability to transmit energy
through a vacuum (i.e., empty space).
Categorizing waves on this basis leads to two
notable categories: electromagnetic waves and
mechanical waves.
24. C) Electromagnetic wave
• An electromagnetic wave is a wave that is capable of
transmitting its energy through a vacuum (i.e., empty
space). Electromagnetic waves are produced by the
vibration of charged particles. Electromagnetic waves
that are produced on the sun subsequently travel to
Earth through the vacuum of outer space.
• Properties:
In vacuum E.M waves travel with light velocity.
E.M waves can be polarized.
E.M waves are transverse in nature.
Medium is not required for propagating the E.M waves.
E.M waves have momentum
conti…
26. D) Mechanical wave
• A mechanical wave is a wave that is not
capable of transmitting its energy through a
vacuum. Mechanical waves require a medium
in order to transport their energy from one
location to another. A sound wave is an
example of a mechanical wave.
27. CONCLUSION
• Telecommunication is an impartment area of
information technology.
• Telecommunications include the Internet and
cellular phone networks.
• The developments over the past two decades
have paved the way to the growth of computer-
based information system and services.
• Most new telecommunications wiring is done
with cables that are optimized for digital
communication, such as fiber optic cables and
digital phone lines.
