PowerPoint Presentation

Telecommunication PrinciplesGroup 01

Communication

Communication is the meaningful Exchange of information between two or more participants Communication requires a sender, a message, a medium and a receiverCommunication system is to transfer information from one point to other point via some communication link

TelecommunicationTelecommunication is the transmission of information over significant distances to communicate.

MessageMessage defined as the physical manifestation As produced by the source.There are two types of message categoriesAnalog messageDigital message

Analog message 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)

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

TransducerTransducer 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.

Transducer

Elements of a Communication systemThere are three essential parts of any communication systemThe transmitter(sender)Transmitter channelReceiver

The TransmitterThe 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

Transmission ChannelThe 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.

Transmission Channel

The ReceiverThe 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 DecodingFiltering

The Mode of Channel Operation

SimplexDuplex

Half Duplex (HDX)

Full Duplex(FDX)

SimplexData 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)

Receiver

Half-Duplex(HDX)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

Half-Duplex(HDX)

Full-Duplex(FDX)Data can travel in both directions simultaneously.E.g.:- The telephone

Undesirable effect in the course of signal transmissionDistortionInterferenceNoiseAttenuation

AttenuationA Loss of energy in wave

Distortion

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

Noise

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

Interference

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

ModulationModulation 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.

Types of modulationAmplification modulationThe information signal changes the amplitude of the carrier wave without changing its frequency or phase.Frequency modulationThe information signal changes the frequency of the carrier wave without changing its amplitude or phase.Phase modulationThe information signal changes the phase of the carrier wave without changing its frequency or amplitude.

Communication system

transmitterReceiver

Thank you for your attention

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