DAC (B-TECH Computer Science Engineering 3rd)

Section A: Communication system components:

Introduction to Communication: Definition & means of communications; Digital and analog

signals: sign waves, square waves; Properties of signals: amplitude, frequency, phase;

Theoretical basis for data communication: Fourier analysis: Fourier series and Fourier

Transform (property, ESD, PSD and Raleigh) effect of limited bandwidth on digital signal.

Section B: Data Transmission System:

Physical connections: modulation, amplitude-, frequency-, phase- modulation; Data

encoding: binary encoding (NRZ), Manchester encoding, differential Manchester encoding.

Transmission Media: Twisted pair-, co-axial-, fiber optic-cables, wireless media

Transmission impairments: attenuation, limited bandwidth of the channels, delay distortion,

noise, data rate of the channels (Nyquist theorem, Shannon limit). Physical layer interfaces:

RS 232, X.21

Section C: Standards in data communications:

Communication modes: simplex, half duplex, full duplex; Transmission modes: serial-,

parallel-transmission; Synchronizations: Asynchronous-, synchronous-transmission; Type of

services: connection oriented-, connectionless-services; Flow control: unrestricted simplex

protocol, simplex stop- and -wait protocol, sliding window protocol; Switching systems:

circuit switching; picketing switching: data gram , virtual circuits, permanent virtual circuits.

Telephone Systems: PSTN, ISDN, asynchronous digital subscriber line.

Multiplexing: frequency division-, time-, wave- division multiplexing

Section D: Security in data communications:

Transmission errors: feedback-, forward-error control approaches; Error detection; Parity

check, block sum check, frame check sequences; Error correction: hamming codes, cyclic

redundancy check; Data encryption: secret key cryptography, public key cryptograph; Data

compression: run length encoding, Huffman encoding.