ENGINEERING ASSISTANT Syllabus

Date of Exam: 17/05/2012 Thursday 11.00 AM to 12.15 PM

(Maximum Marks : 100)

(Duration: 1.15 Hours)

( Medium of Questions: English  )

I.ELECTRONIC DEVICES AND CIRCUITS


Diodes: Semiconductors – PN Junction diode – Forward and reverse
bias characteristics – specifications – Zener diode – construction and
working principle – characteristics – Zener break down – Avalanche
break down – Zener diode as a voltage regulator – applications –
specifications.
Rectifier:Introduction – Classification of Rectifiers – Half Wave rectifier
– Full Wave rectifier – Bridge rectifier – Efficiency – Ripple factor –
Applications – Filters – C, LC and PI filters.
Transistor: Transistor as an amplifier –Transistor biasing – Fixed bias,
Collector base bias, Self bias – CB, CE, CC Configurations –
Characteristics – comparison between three configurations in terms if
input impedance, output impedance, current gain, voltage gain – RC
coupled amplifier – Load characteristic analysis – Emitter follower and
its applications – Negative feed back – Transistor as a switch.
Transistor oscillator – classifications – condition for oscillation
(Barkhausen criterion) – General form of LC oscillator – Hartley
oscillator – Colpitts oscillator – RC phase shift oscillator , Crystal
oscillator .
Field Effect Transistor:  Construction – working principle of FET –
Difference between FET and BJT – characteristics of FET –
specifications – FET amplifier (Common source amplifier), FET as
CHOPPER, UJT – construction – equivalent circuit – operation
-characteristics – UJT as a relaxation oscillator.   MOSFET – construction
– characteristics – MOSFET as a switch  - CMOS basic concept IGBT –
Basic principle – IGBT as a switch.
Opto – Electronics Devices and Waveshaping Circuits:  LDR,
LED,  7 segment LED, LCD, Opto coupler –Opto interruptor – Infraredtransmitter and  Receiver – Laser Diode – Solar Cell – Avalanche
Photodiode – Photo transistor.   Diode clipper – Types – Clamper
circuits using diode – Voltage doubler – Astable, Monostable and
Bistable operations using Transistor.
Operational Amplifier :  Ideal op.Amp – Block diagram and
characteristics – (Minus input follows Plus input and no current through
Minus and Plus input) – Op-amp parameters- CMRR – Slew rate –
Virtual ground – Applications of op-amp-Inverting amplifier – Summing
amplifier – Non inverting amplifier – Voltage follower – Comparator –
Zero crossing detector – Integrator – Differentiator – Op.Amp
specifications. 555 Timer – Functional Block diagram – Astable,
Monostable and Schmitt Trigger – Sequence timer.  IC voltage
regulator – 3 pin IC regulators – 78xx,  79xx, LM 317.
D/A Convertor:  Basic concepts – Weighted Resistor  D/A convertor –
R-2R Ladder D/A convertor – Specification of DAC IC Sampling and
quantization – Analog to digital conversion using Ramp method –
Successive approximation method – Dual slope method, simultaneous
method voltage to frequency convertor – Frequency  to voltage
convertor specification of A/D convertor.

II. ELECTRONIC COMMUNICATION


Networks: Symmetrical and asymmetrical networks, characteristic
impedance and propagation constant deviation of characteristic
impedance for T and Pi networks using Zoc and Zsc, image and iterative
impedances – Derivation of Z11  and  Z12   for assymetrical T and L Networks
using Zoc and Zsc,  Derivation of iterative impedances  for assymetrical T
network.  Equaliser : Types, applications, constant resistance equalizer.  (No
derivations)
Attenuator: types, derivations for elements of symmetrical T and Pi
networks – application.
Filters: types and definitions – derivations for circuit elements and cut off
frequencies of LPF and HPF only.  Transmission lines (No equations and
derivations):  Transmission line equivalent circuit, primary and secondary
constants, travelling and standing waves, SWR, Wave guides:
types,advantages.
Antennas & Propagation:  Basic antenna principle, directive gain,
directivity, radiation pattern, broad-side and end-fire array, Yagi antenna,
Parabolic antenna.        Ground wave propagation, space waves, ionospheric
propagation.
Modulation:  Electromagnetic Frequency spectrum.  Need for modulation,
types of modulation.  Amplitude modulation: expression, AM spectrum andside bands, types of AM – balanced modulator.  SSB generation – phase shift
and filter methods, advantages and disadvantages of SSB, AM VSB System.
Diode detector      AM Transmitter : Types of Transmitters, Block diagram –
high level AM transmitter and low  level AM transmitter. SSB transmitter, ICW
and MCW principles .   AM receiver: TRF receiver, superheterodyne radio
receiver  - explanations of individual stages – AGC types,  SSB receiver
Frequency modulation:   Expression, wave forms, frequency spectrum ,
effects of noise in FM, comparison of AM and FM, varactor diode modulator.
FM detectors – slope detector, phase discriminator, ratio detector (no
derivation)
FM  Transmitters :  Direct and Indirect methods – stereophonic FM
transmitter.
FM Receiver :  Block Diagram – AFC – Stereophonic FM receiver
Phase modulation:  Principles, Phase modulator circuit, comparison
between FM and PM
Pulse modulation:  Types, Sampling Theorem, Generation and detection of
PAM, PWM and PPM, PCM – transmitter, receiver, quantizing noise –
companding.
Microphones: Construction and performances of the following microphones:
carbon, condenser, peizo electric, moving coil and velocity ribbon.
Loud Speakers:  Constructional details of dynamic cone type, Horn type and
electrostatic  loud speakers, woofer, midrange and tweeter  ; cross over
network, surround – sound systems
Audio recording and reproduction:  Magnetic system  - Compact Disc
system – MP3 system – DVD System – stereophonic system – Hi-Fi- system
principles –Dolby – DTS.
Monochrome Television :  Scanning principles   aspect ratio – composite
video signal – TV standards. TV transmitter – TV receiver.
Colour TV :  Principles of Colour Transmission and reception –color CCD
camera.   PAL colour TV receiver (IC details not required) Digital Colour TV
receiver LCD display unit – plasma display – principles of Handy Cam ,  LCD
projector principles of CCTV and Cable TV.
Radar: Fundamentals  Basic Radar System – Applications – Radar range
equation – factors influencing  maximum range – Target properties – Pulsed
Systems – Basic Pulsed Radar System – Bloc Diagram – Display methods – PPIdisplay   - Automatic target detection.  Radio aids to navigation – Direction
finding – Radio ranges – Radio Compass  - Radio Telemetry – Instrument
landing system – Ground controlled approach system.
Telephone System :  Public Telephone Network –Private  Telephone
Network – Electronic switching System –Block Diagram –– Cordless Phone –
Block diagram – Video Phone – Block Diagram- ISDN – Architecture – Features.
Facsimile Communication  System:   Introduction – facsimile  sender –
Cyllindrical scanning – Tape scanning  -  facsimile receiver – synchronisation –
phasing – Index of Co-operation  (IOC) – photographic recording – Direct
recording.
Digital Communication:  Fundamental Block Diagram and Basic elements
of digital communication system – Advantages, disadvantages of digital
communication – characteristics of data transmission circuits – Band Width
requirements – speed – Baud rate – Noise – Cross Talk – Distortion – Equalizers
– Echo Compressors.
Digital Codes :   Baudot Code – ASCII Code – EBCDIC Code – Error detection
codes – Parity check codes – Redundant Codes – Constant Ratio Codes – Error
correction codes – Retransmission, forward error correcting code -  Hamming
Code.
Digital modulation techniques :   ASK modulation /demodulation – FSK
modulation / Demodulation – PSK modulation / demodulation – only block
diagram and operation.
Data  sets and interconnection:  Classification of Modems – Modem
interfacing – serial interface standard.
Optical communication:  Optical communication System – Block Diagram –
Need and  advantages of optical fibers – principles of light transmission in a
fibre using Ray theory – Single mode fibers – multimode fibers – step index
fibers –graded index fibers (Fabrication details not required) -Attenuation in
optical fibers – Absorption losses, scattering losses, bending losses, core and
cladding losses, Dispersion – material  dispersion, Wave guide Dispersion,
Intermodal dispersion – optical sources – LED – semi conductor LASER –
principles – optical detectors – PIN and APD diodes – connectors and splices
Optical cables – couplers – optical transmitter – Block diagram using laser feed
back control circuit – optical receiver – Block diagram using APD – Applications
of optical fibers – civil, Industry and Military applications (with descriptive block
diagram)

III.   SATELLITE COMMUNICATION


Satellite System – Kepler’s I, II, II  Laws – Orbits –types – Geostationary
synchronous satellites – Advantages – LEO, MEO – Advantages – Apogee –
Perigee – Active and Passive satellite – Earth Eclipse of Satellite – Launching
Orbit – Parabolic reflector antenna – cassegrain antenna.  Space segment –
power supply – Attitude control – station keeping – Transponders – TT and C
subsystem – Thermal control – Antenna subsystem.  Earth segment – Receive
only Home TV system – Block Diagram – Transmit receive earth station – Block
Diagram .  Satellite Services – INTELSAT – GPS – MSAT

 IV        MOBILE   COMMUNICATION


Cellular  Telephone – Evolution – Fundamental concepts – simplified cellular
telephone system – frequency reuse – Interference –Co – Channel interference
– Adjacent channel Interference – Improving coverage and capacity in cellular
systems – cell splitting – sectoring – Roaming and  Handoff.  Satellite multiple
access techniques – TDMA, FDMA, CDMA
Digital Cellular System – Global system for mobile communications (GSM) –
GSM services – GSM System    Architecture – Radio subsystem.

NOTE: - It may be noted that apart from the topics detailed above, questions from other topics prescribed for the educational qualification of the post may appear in the question paper. There is no undertaking that all the topics above may be covered in the question paper.