The document outlines the fundamentals of data communication and computer networking, including concepts such as data representation, encoding, modulation, and transmission modes. It also details various encoding and modulation techniques, along with the differences between serial and parallel communication, synchronous and asynchronous transmission, and the operation of modems. Key encoding methods discussed include amplitude shift keying, frequency shift keying, and phase shift keying.

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EDT 4608
DATA COMMUNICATION & COMPUTER
NETWORKING
Introduction to Data
Communication

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DATA REPRESENTATION
Refers to the methods used internally to represent information stored
in a computer.
Human speech is analog because it uses continuous (wave form)
signals that vary in strength and quality

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DATA REPRESENTATION

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DATA REPRESENTATION

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ENCODING
Encoding is the process of converting data from one form to another.

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TYPE OF ENCODING
1. Analog to analog encoding
2. Analog to digital encoding
3. Digital to analog encoding
4. Digital to digital encoding

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DATA ENCODING AND DECODING
 Data Encoding is the process of putting a sequence of characters
(letters, numbers, punctuation, and certain symbols) into a
specialized format for efficient transmission or storage.
 Decoding is the opposite process -- the conversion of an encoded
format back into the original sequence of characters.

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DIGITAL TO ANALOG ENCODING
Amplitude shift keying (ASK): is a form of modulation which
represents digital data as variations in the amplitude of a carrier
wave. Two different amplitudes of carrier frequency represent '0' ,
'1'.

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DIGITAL TO ANALOG ENCODING
Frequency shift keying (FSK): In Frequency Shift Keying, the change
in frequency define different digits. Two different frequencies near
carrier frequency represent '0' ,''1'.

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DIGITAL TO ANALOG ENCODING
Phase shift keying (PSK): is a digital modulation scheme that conveys
data by changing, or modulating, the phase of a reference signal (the
carrier wave).

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DATA MODULATION
Modulation is a process of mixing a signal with a sinusoid to produce
a new signal. This new signal, conceivably, will have certain benefits
over an un-modulated signal, especially during transmission.
Data modulation is a process of blending data into a carrier signal.
At the receiving side, a device demodulates the signals by separating
the constant carrier signals from the variable data signals

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TYPE OF MODULATION
Amplitute Modulation (AM)
 a type of modulation where the amplitude of the carrier signal is modulated
(changed) in proportion to the message signal while the frequency and phase are
kept constant.
Frequency Modulation (FM)
 a type of modulation where the frequency of the carrier signal is modulated
(changed) in proportion to the message signal while the amplitude and phase are
kept constant.
Phase Modulation (PM)
 a type of modulation where the phase of the carrier signal is varied accordance to
the low frequency of the message signal is known as phase modulation.

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MODEM – MODULATOR/DEMODULATOR
A modem (modulator-demodulator) is a device that modulates an
analog carrier signal to encode digital information and demodulates
the signal to decode the transmitted information

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FREQUENCY CLASSIFICATIONS

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FREQUENCY CLASSIFICATIONS

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MODE OF DATA TRANSMISSION
Serial & Parallel
Synchronous and asynchronous,
Simplex, Full duplex and half duplex;

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DIFFERENCE BETWEEN SERIAL AND
PARALLEL TRANSMISSION
a serial link transmits a single stream of data, one bit at a time.
Eg. USB, RS232 (serial port)
RS-232 Cable

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DIFFERENCE BETWEEN SERIAL AND
PARALLEL TRANSMISSION
is a method of conveying multiple binary digits (bits) simultaneously..
Eg.

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SIMPLEX, HALF DUPLEX, FULL DUPLEX
COMMUNICATION

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SIMPLEX, HALF DUPLEX, FULL DUPLEX -
EXAMPLE
Half Duplex Full Duplex

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SYNCHRONOUS AND ASYNCHRONOUS
COMMUNICATION
Asynchronous serial communication describes a
serial communication protocol in which a start signal is sent prior to
each byte, character or code word and a stop signal is sent after
each code word, so as to make the communication asynchronous. The
start signal serves to prepare the receiving mechanism for the
reception and registration of a symbol and the stop signal serves to
bring the receiving mechanism to rest in preparation for the reception
of the next symbol.

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SYNCHRONOUS AND ASYNCHRONOUS
COMMUNICATION
Synchronous data transmission is a data transfer method in which a
continuous stream of data signals is accompanied by timing signals
(generated by an electronic clock) to ensure that the transmitter and
the receiver are in step (synchronized) with one another. The data is
sent in blocks (called frames or packets) spaced by fixed time
intervals.