Monday, March 29, 2010

Questiom of TELECOMMUNICATION SYSTEMS (sem-5) -2009

                               TELECOMMUNICATON SYSTEM

1. Choose the correct Alternative.
 (1) In modem uploading data rates always less then downloading data rates because
   (i) SNR (20db)is very low in communication channel.
   (ii) quantisation noise limits the channel data rates
   (iii) during uploading extra control bits are added with the data
   (iv) none of these.
 (2) the voice signal BW is 4 KHz and the Nyquist sampling rate is 8 KHz and time multiplexed space swiching 30 channel is to be multiplexed. the TS is
   (i) 4.16 micro sec (ii) 8.33 micro sec. (iii)125 micro sec (iv) none of these
 (3) MTTR means
   (i) Mean time to repair (ii) Maximum time to repair
   (ii) Most time to repair (iv) mean time to represent.
 (4) Blocking probability is
    (i) call congestion (ii) time congestion (iii) both (i) and (ii). (iv)none of these
 (5) GOS in india is
   (i)0.002 (ii) 0.02 (iii) 0.2 (iv) 2.
  (6) ISDN B-channel carries data and service at
    (i) 16 kbps (ii) 32 kbps (iii) 64 kbps (iv) 1.544 Mbps
 (7) Loudspeaker is an end instrument of
   (i)transmitter side (ii) receiver side (iii) both (iv) none of these
 (8) CHILL is a
    (i) CCITT language (ii) IEEE language (iii) IEE language (iv) ANSI language.
 (9) Attenuation can be reduced in subscriber loop by using
   (i) higher diameter in copper wire (ii) series of inductance in line
   (iii) lower diameter in copper wire (iv) serise of capacitance in line.
 (10) SDL stands for
    (i) software description language (ii) specification derived language
    (iii) specification description language (iv) sofeware derive language.
(11) A subscriber makes 3 calls of 3 mints , 4 mints, and 2 mints duaration in one hour period Calculate the subscriber traffic in Erlangs.
   (i)0.15 E (ii) 0.2E (iii)0.5E (iv) 0.7 E
 (12) In a  Strowger system the high value of CCI indicates
   (i) good design (ii) poor design (iii) no impact on design (d) none of these
                       GROUP - B
 Answer any three
 2 (a) What do you mean by point to point communication ?
   (b) Explain the disadvantages of this system
   (c) If the number of node in point to point communication is 770 , find out the total number of links required for total connevtivity.
3. (a) Show the GOS =  p b  , explain the meaning of the symbol.
   (b) Over a 20 minute observation interval, 40 subscribers initiate calls. Total duration of the calls is 4800 sec . calculate the load offered to the network by the sescribers and the average subscriber traffic.
4. What is call completion rate (CCR) ? 10000 subscribers are connected to an exchange , if the exchange is designed to achieve a CCR of 0.8 when the busy hour calling rate is 4.8 , calculate BHCA of the exchange.
5. What is BORSCHT function ? Why is this important in electronics exchange.
6. How many type of transmission medi are used in telecommunication ? What are the advantages of twisted pair cable over parallel wire cable ? what is step index fiber and graded index fiber?
                    GROUP -C
Answer any there
7 (a) assuming simultaneously forward and backward wave propagation in a transmission line. Derive the follwing general equation for the line,
    V=V1cos hrd +I1Z0sinhrd,
    I= I1coshrd+I1/Z0 sinhrd,
   Where V and I are the voltage and current respectively at a distance from a load end of the transmission line having characteristic independence Z0 and propagation constant r. the load end voltage and current V1 and I1respectively.
 (b) A loseless line has a characteristics impedance of 75 ohm and is terminated in a load of 300 ohms . find out the reflection cofficient and VSWR in the line.
  (c) explain the principle of DTMF dialing.
8. (a) what ia ISDN? Explain the transmission channel in ISDN?
   (b) what are the drawbacks of ISDN? how does B-ISDN overcome from this?
  (C) Write function grouping and reference point in ISDN.
9. (a) Explain centralized SPC and different modes of it.
(b) Explain distributed SPC and explain the different types of leve processing in it.
 (c) In the load sharing configuration of centralised SPC MTBF =2000 hours and MTTR =4 hours calculate the unavailability for single and dual processor system.
(d) Explain time division space switching.
10. What is DTE and DCE? Explain how data communication takes place between DTE and DCE using RS @#@C serial interface. why is conventional telephone modem down stream data rate 56 kbps? A telephone line has a bandwidth of 3000 Hz and SNR is 34 Db calculate the data rate of this line.
11. Write short notes on any three of the following.
(A) Packet switching
(b) ISDN systems interface.
 (c) Difference between circiut switch , packet swith and message swith
(d) Modems and standards
(e) facsimile transmission.

Sunday, March 28, 2010


1. An impulse turbine
(A) Makes use of a draft tube
(B) Always operates submerged
(C) Converts the pressure head into velocity
head through the vanes
(D) Is most suited for low head installations
2. Power required to drive a centrifugal
pump is directly proportional to
(A) Diameter of its impeller
(B) Square of diameter of its impeller
(C) Cube of diameter of its impeller
(D) Fourth power of diameter of its
3. The locus of the common point on the
two meshing spur gears is known as
(A) Addendum circle
(B) Duodenum circle
(C) Pitch circle
(D) Base circle
4. When there is a reduction in amplitude
over every cycle of vibration then the body
is said to have
(A) Free vibration
(B) Forced vibration
(C) Damped vibration
(D) Natural vibration
5. For machining at high speed the tool
material should have
(A) Wear resistance
(B) Red hardness
(C) Toughness
(D) All of these
6. MIG welding is
(A) A gas welding process
(B) An electric resistance welding process
(C) A electric resistance welding process
(D) A forge welding process involving high
temperatures and low pressures
7. The ability of sand to permit the metal to
shrink when it solidifies is known is
(A) Plasticity (B) Permeability
(C) Collapsibility (D) Cohesiveness
8. Rivets are generally specified by
(A) Overall length
(B) Shank diameter
(C) Thickness of plates to be jointed
(D) Diameter of head
9. Which of the following is steady flow
(A) Reciprocating compressor
(B) Centrifugal compressor
(C) Voot blower
(D) Vane blower
10. A closed cycle gas turbine works on
(A) Carnot cycle (B) Rankine cycle
(C) Brayton cycle (D) Joule cycle
11. Thermal conductivity of solid metals
(A) Decreases with rise in temperature
(B) Does not vary with temperature
(C) Increases with rise in temperature
(D) Remains constant with rise in
12. During adiabatic saturation process, air
property which remains constant, is known
(A) Wet bulb temperature
(B) Dry bulb temperature
(C) Relative humidity
(D) Specific humidity
13. Bell-Coleman cycle as applied to
refrigeration operates
(A) On open air system
(B) On vapour compression system
(C) On vapour absorption system
(D) On none of these
14. The gears in which axes of the shaft
connected by them, intersect, are known as
(A) Spur gears (B) Bevel gears
(C) Spiral gears (D) Gear train
15. Shot peening
(A) Is done at re-crystallization temperature
(B) Changes the crystalline structure at
(C) Improves the fatigue life of small parts
(D) Refines the grain structure
16. In a bomb calorimeter the heat released
by the fuel is absorbed by
(A) Atmospheric air
(B) Water
(C) Metal container
(D) Bomb, water and metal container
17. Nitriding is done
(A) On low carbon steels only
(B) To impart blue colour to steels
(C) To improve machinability
(D) To increase surface hardness
18. The extent of cold work that a metal can
withstand depends on
(A) Purity of metal
(B) Carbon percentage
(C) Ductility
(D) Room temperature
19. Which engine has the highest air fuel
(A) Petrol engine (B) Gas engine
(C) Diesel engine (D) Gas turbine
20. Annealing of steels is done to
(A) Remove internal stresses
(B) Produce soft core under hard surface
(C) Produce hard core under soft surface
(D) Introduce capacity to withstand shocks


The model question paper only offers a broad overview and does not purport to represent either
the syllabus or the pattern of questions that would appear in the Engineering Knowledge Test
1. In a communication system, noise is
most likely to get into the system
(A) at the transmitter
(B) in the channel
(C) in the information source
(D) at the destination
2. When modulation frequency is doubled,
the modulation index is halved, and the
modulating voltage remains constant, the
modulation system is
(A) amplitude modulation
(B) phase modulation
(C) frequency modulation
(D) angle modulation
3. Impedance inversion may be obtained
(A) a short – circuited stub
(B) an open – circuited stub
(C) a quarter – wave line
(D) a half – wave line
4. HIGH frequency waves are
(A) observed by the F2 layer
(B) reflected by D layer
(C) capable of use for long-distance
communication on the moon
(D) affected by the solar cycle
5. Which one of the following terms does
not apply to the Yagi-uda array
(A) Good band width
(B) Parasitic elements
(C) Folded diploe
(D) High gain
6. A duplexer is used
(A) to couple two different antennae to a
transmitter without mutual interference
(B) to allow one antenna to be used for
reception or transmission without mutual
(C) to prevent interference between two
antennae when they are connected to
(D) to increase the speed of the pulses in
pulsed radar
7. Indicate which of the following system is
(A) Pulse – Position modulation
(B) Pulse – Code modulation
(C) Pulse – Width modulation
(D) Pulse – Frequency modulation
8. A forward error correcting code corrects
errors only
(A) requiring partial retransmission of the
(B) requiring retransmission of entire signal
(C) using parity to correct to errors in all
(D) requiring no part of the signal to be
9. A typical signal strength received from a
geosynchronous communication satellite is
of the order of
(A) a few milli watts
(B) kilo watts (C) watts
(D) few pico watts
10. Telephone traffic is measured
(A) with echo cancellers
(B) by the relative congestion
(C) in terms of the grade of service
(D) in erlangs
11. Positive logic in a logic circuit is one in
(A) logic 0 and 1 are represented by 0 and
positive voltage respectively
(B) logic 0 and 1 are represented by
negative and positive voltages respectively
(C) logic 0 voltage level in higher than
logic 1 voltage level
(D) logic 0 voltage level is lower than logic
1 voltage level
12. A half-adder can be made from
(A) two NAND gates
(B) a NOT gate and an OR gate
(C) an AND gate and an OR gate
(D) an AND gate and an X-OR gate
13. Which of the following devices has its
characteristics very close to that of an ideal
current source.
(A) Field effect transistor
(B) Transistor in common bas mode
(C) Zener diode
14. The main use of a common base
transistor amplifier is
(A) as voltage amplifier
(B) current amplifier
(C) for matching a high source impedance
to a low load impedance
(D) for rectification of a.c. signal
15. A class-B amplifier is biased
(A) Just at cut-off
(B) nearly twice cut-off
(C) at mid point of load line
(D) so that IB equals jut IC
16. If the peak transmitted power in a radar
system is increased by a factor of 16, the
maximum range will be increased by a
factor of
(A) 2 (B) 4 (C) 8 (D) 16
17. A high PRF will (indicate the false
(A) make the returned echoes easier to
distinguish from noise
(B) make target tracking easier with conical
(C) increase the maximum range
(D) have no effect of the range resolution
18. A solution to the “blind speed” problem
in a radar system is to
(A) change the Doppler frequency
(B) vary the PRF
(C) use mono pulse
(D) use MTI
19. The number of active picture elements
in a television image depends on
(A) fly back time
(B) CRT screen size
(C) received band width
(D) FB ratio of receiver antenna
20. In a colour TV, the three primary
colours are
(A) red, orange and blue
(B) red, blue and green
(C) red, green and yellow
(D) red, orange and green

Modal Question Paper for EKT General Engineering

Part A: General Engineering
1. The probability of hitting a target from
one gun 9/10, from another gun is 7/10. If
both gun are fired at the same time, the
probability of hitting the target is
(A) 2/20 (B) 63/100
(C) 16/20 (D) 63/20
2. If the three vectors a, b and c are
coplanar , then the missed product a x b. c
(A) Zero (B) Non-Zero
(C) Unity (D) Non of these
3. Limit sin x is
x→0 x
(A) not defined (B) 1
(c) zero (D) -1
4. The Laplace transform of sin23t is
(A) 18 (B) 18
S(S2+36) S2(S+36)
(C) 18 (B) 18
(S+36) (S+36)(S+4)
5. The function
x2 for x< 3
2x+3 for x>3
(A) continuous over the entire number scale
(B) continuous at x=3 but discontinuous at
all other points
(C) discontinuous at x=3 but continuous at
all other points
(D) discontinuous everywhere
6. When a body hits an obstacle, the force
with which it hits the obstacle depends
upon its
(A) average velocity
(B) velocity at the instant of collision
(C) initial velocity
(D) all of these
7. The wavelength of visible light is of the
order of
(A) 1μm (B) 100 μm
(C) 1mm (D) 1 Å
8. Whenever a source of sound moves
towards an observer
(A) the frequency heard by the observer is
less than that of the source
(B) the frequency heard by the observer is
greater than that of the source
(C) the frequency heard by the observer is
(D) the wavelength of sound heard is
greater than that of the sound emitted
9. Moving electric charges will interact
(A) electric field only
(B) magnetic field only
(C) both of these
(D) none of these
10. Gamma radiation is most similar to
(A) sound waves (B) X-ray
(C) Alpha particles (D) neutrons
11. The fundamental particle responsible
for keeping the nucleus together is
(A) meson (B) anti proton
(C) positron (D) muon
12. Air contains 21% oxygen by volume
and the rest nitrogen. If the barometer
pressure is 740 mm of Hg the partial
pressure of oxygen is close to
(A) 155 mm of Hg
(B) 310 mm of Hg
(C) 465 mm of Hg
(D) 162 mm of Hg
13. In the electrolytic cell
(A) electrical energy is converted into
chemical energy
(B) chemical energy is converted into
electrical energy
(C) mechanical energy is converted into
potential energy
(D) potential energy is converted into
kinetic energy
14. The force required to maintain a body at
constant speed in free space is equal to
(A) the mass of the body
(B) zero
(C) the weight of the body
(D) the force required to stop it
15. If the length of a spring is halved, the
spring constant becomes
(A) half (B) 1/4th
(C) double (D) four times
16. The coefficient of static friction
depends on
(A) the material of the bodies in contact
(B) the quality of surface finish of the
(C) the presence of foreign matter between
the surface
(D) all of these
17. The units of angular impulse in SI
system are
(A) Nms (B) Ns
(C) Nm/s (D) Ns/m
18. A particle is projected with a velocity
3 ½ ½
(A) gR (B) gR
2 3
½ ½
(C) gR (D) 2gR
19. Stainless steel contains iron and
(A) Chromium and nickel
(B) Chromium and carbon
(C) Nickel and carbon
(D) Chromium and manganese
20. The property of material by which it
offers resistance to scratching or
indentation is called
(A) Brittleness
(B) Hardness
(C) Toughness
(D) Resilience
21. The failure of a material due to repeated
stressing is known as
(A) Creep
(B) Fracture
(C) Fatigue
(D) Brittle Fracture
22. The electric device which blocks DC
but allows AC is called
(A) Capacitor
(B) Inductor
(C) Amplifier
(D) Transducer
23. When a charge is moved from one point
to another in an electric field, the work
done is
(A) independent of the path
(B) zero along the direction of the field
(C) measured in Joules per metre
(D) measure in Volt per metre
24. A capacitor with lowest leakage is
(A) Paper (B) Ceramic
(C) Polyester (D) Mica
25. A zener diode operates
(A) In an extremely high forward bias
(B) In an extremely low reverse bias
(C) In an extremely low forward bias
(D) In a reverse bias higher than laid down
26. The specific gravity of a lead acid cell
is often used as a measure of its
(A) Rate of discharge
(B) Operating temperature
(C) State of charge
(D) Life expectancy
27. An uniformly distributed load is one
(A) Acts at a point on a beam
(B) Spreads uniformly over the whole
length of a beam
(C) Varies uniformly over the whole length
of a beam
(D) loads the beam from one end only
28. A steam engine device which keeps the
speed of the engine, all loads, constant is
known as
(A) Flywheel
(B) Eccentric
(C) Connecting rod
(D) Governor
29. The refrigerant hiving the lowest
freezing point is
(A) Ammonia
(B) Carbon dioxide
(C) Freon – 11
(D) Freon – 22
30. Heat and work are
(A) Path functions
(B) Properties of a substance
(C) Point functions
(D) Absolute units

EKT (Engineering Knowledge Test) exam scheme

Engineering Knowledge Test is a common test aimed at testing the Basic Engineering knowledge of the candidates applied for
Aeronautical Engineering Courses. EKT has two parts, namely
Part A - General Engineering: 40 Questions Duration: 1 Hour
Part B - Specialist Paper for each Engineering discipline: 35 Questions
Engineering Knowledge Test is pitched at pre-final to final year engineering level. The test consists of two parts viz General Engineering
and Specialist subjects for the two streams of Technical Branches i.e Aeronautical Engineering (Electronics) and Aeronautical
Engineering (Mechanical).
The specialised papers are in Mechanical Engineering, Aeronautical engineering, Electronics and Communication engineering, Electrical
and Instrumentation engineering and Computer Engineering.
The questions are objective type in nature and duration of test is approximately one hour. It is mandatory for the candidates to pass in
both General and Specialist papers to qualify for AFSB interview.