very basic.usfull for 1st year students

4. Telecommunication
Telecommunication is the transmission of
information over significant distances to
communicate.

5. Message defined as the physical
manifestation As produced by the
source.
There are two types of message
categories
1. Analog message
2. Digital message

6. • An analog message is a physical quantity
that varies with time usually in a smooth
and continuous fashion.
• E.g.-Sine wave, Voice, Video (TV)

7. Digital message
•A digital message is an ordered sequence of
symbols selected from a finite set of discrete
elements
• E.g.-Telegraph (Morse code),Continuous wave
(CW) code, Serial binary code (used in
computers)

8. Transducer is a device that converts a signal in
one form of message to another form of
message.
The input transducer converts the message to
an electrical signal say a voltage or current.
Another transducer at the destination
converts the output signal to the desired
message form.

9. Transducer

10. There are three essential parts of any
communication system
1.The transmitter(sender)
2.Transmitter channel
3.Receiver

11. The transmitter processes the input signal to
produce a suitable transmitted signal suited to
the characteristics of the transmission
channel.
Signal processing for transmission almost
always involves modulation and may also
include coding

12. The transmission channel is the medium by
which the electrical signal is transmitted from
one place to another.
It may be a pair of wires, a c co-axial cable,
radio wave or laser beam.
Every channel introduces some amount of
transmission loss or attenuation.

13. Transmission Channel

14. The receiver operates on the output signal
from the channel in preparation for delivery to
the transducer at the destination.
Other Receiver operation are,
• Amplification to compensate for
transmission loss.
• Demodulation and Decoding
• Filtering

15. Simplex Duplex
Half Duplex (HDX) Full Duplex(FDX)

16. Data in a simplex channel is always one way.
It is not possible to send back error or control
the signals to the transmit end.
Ex:- Radio, TV broadcasting, Beeper (personal
receiver)

17. A HDX channel can send and receiver, but not
at same time.
Only one end transmits at a time, the other
end receives.
It possible to perform error detection and
request the sender to retransmit information
that arrived corrupted.
E.g.-Police, military radio transmissions,
Citizen band (CB),Family radio, Amateur radio

19. Data can travel in both directions
simultaneously.
E.g.:- The telephone

20. Undesirable effect in the
course of signal
transmission
Distortion
Interference
Noise
Attenuation

21. Attenuation
A Loss of energy in wave

22. Distortion
• Distortion is the alteration of the original
shape of an object waveform.

23. Noise
• Noise is random, undesirable electronic
energy that enters the communication system
via the communicating medium and interferes
with the transmitted message.

24. Interference
• Interference is anything which modifies or
disrupts a signal as it travels along a channel
between a source and a receiver.

25. Modulation
Modulation is the process of generating
modulated carrier wave by combining the low
frequency signal (information/message) with a
very high frequency radio wave called carrier
wave.
Modulation makes the information signal
more compatible with the medium.

26. Types of modulation
Amplification modulation
The information signal changes the amplitude of the
carrier wave without changing its frequency or phase.
Frequency modulation
The information signal changes the frequency of the
carrier wave without changing its amplitude or phase.
Phase modulation
The information signal changes the phase of the carrier
wave without changing its frequency or amplitude.

27. Communication system
transmitter Receiver