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  #1  
Old Sunday, April 02, 2017
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Default Jobs in Pakistan Telecommunication Authority (PTA) - April 2017

Assalam O Alaikum Dear Members!

Multiple Jobs in Pakistan Telecommunication Authority (PTA) have been announced.

Ad can be seen below:


Ad Published in Daily Jang dated 02 April 2017: http://e.jang.com.pk/04-02-2017/pindi/page35.asp
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Question Anyone Applied

Anyone Applied and got test/interview call for this Job ?
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yes, i have applied to against the post of assistant director technical and yesterday, i have also call them and confirming that, the test will be conducting after eid. admission slip would be upload in the first week of June.
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Old Wednesday, May 24, 2017
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these are important mcqs for pta AD technical
Q1 IN A COMMUNICATION SYSTEM NOISE IS MOST LIKELY TO AFFECT THE SIGNAL
(a) at the transmitter
(b)in the channel
(c)in the information source
(d)at the destination
ans-b

Q2 INDICATE THE FALSE STATEMENT .MODULATION IS USED TO
(a)reduce the bandwidth used
(b)separate different transmissions
(c)ensure that intelligence may be transmitted over long distances
(d)allow the use of practical antenna
ans-a

Q3 ONE OF THE FOLLOWING NOISE BECOME OF GREAT IMPORTANCE AT HIGH FREQUENCY.IT IS THE
(a)shot noise
(b)random noise
(c)impulse noise
(d)transit time noise
ans-d

Q4 INDICATE THE FALSE STATEMENT
(a)hf mixer are generally nosier than hf amplifiers
(b)impulse noise voltage is independent of bandwidth
(c)thermal noise is independent of frequency at which it is measured
(d)industrial noise is usually of impulse type
ans-b
Q5 THE VALUE OF THE RESISTOR CREATING THERMAL NOISE IS DOUBLED .THE NOISE POWER IS
(a)halved
(b)quadrupled
(c)doubled
(d)unchanged
ans-d

Q6 ONE OF THE FOLLOWING IS NOT A USEFUL QUANTITY FOR COMPARING THE NOISE PERFORMANCE OF RECEIVERS
(A)i/p noise voltage
(b)equivalent noise resistance
(c)noise temp
(d)noise figure
ans-a


Q7 INDICATE THE NOISE WHOSE SOURCE IS IN A CATEGORY DIFFERENT FROM THAT OF OTHER THREE
(A)solar noise
(B)cosmic noise
(C)atmospheric noise
(D)galgatic noise
ans-c

Q8 IN A LOW LEVEL AM SYSTEM ,AMPLIFIERS FOLLOWING THE MODULATED SIGNAL MUST BE
(a)linear
(b)harmonic devices
(c)class c amplifiers
(d)non linear devices
ans-a

Q9 LEAK TYPE BIAS IS USED IN A PLATE MODULATED CLASS C AMPLIFIER TO
(A)prevent tuned circuit damping
(b)prevent excessive grid current
(c)prevent over modulation
(d)increase the bandwidth
ans-b

Q10 THE O/P STAGE OF A TELEVISION TRANSMITTER IS MOST LIKELY TO BE A
(a)plate modulated class c amplifier
(b)grid modulated class c amplifier
(c)screen modulated class c amplifier
(d)grid modulated class a amplifier
ans-b
Q11 THE MODULATION INDEX OF AN AM IS CHANGED FROM 0 TO 1 .THE TRANSMITTED POWER IS
(a)unchanged
(b)halved
(c)doubled
(d)increased by 50%
ans-d

Q12 ONE OF THE ADVANTAGE OF BASE MODULATION OVER COLLECTOR MODULATION OF A TRANSISTOR CLASS C AMPLIFIER IS
(a)the lower modulation power is required
(b)higher power o/p per transistor
(c)better efficiency
(d)better linearity
ans-a


Q13 AM IS USED FOR BROADCASTING BECAUSE
(A)it is more noise immune than other information system
(b)compared with other it requires less transmitting power
(c)its use avoids receiver complexity
(d)no other modulation system can provide the necessary bandwidth for high fidelity
ans-c

Q14 THE MOST COMMONLY USED FILTERS IN SSB GENERATIONS ARE
(A) mechanical
(b)rc
(c)lc
(d)low pass
ans-a

Q15 IN AN SSB TRANSMITTER ONE IS MOST LIKELY TO FIND A
(a)class c audio amplifier
(b)tuned amplifier
(c)class b rf amplifier
(d)class a rf o/p amplifier
ans-c

Q16 ONE OF THE FOLLOWING CANNOT BE USED TO REMOVE THE UNWANTED SIDEBAND IN SSB. THIS IS THE
(A)filter system
(b)phase shift method
(c)third method
(d)balanced modulator
ans-d

Q17 IN THE SPECTRUM OF A FM WAVE
(a)the carrier frequency disappears when the modulation index is large
(b)the amplitude of any side band depends on the modulation index
(c)the total number of sidebands depends on the modulation index
(d)the carrier frequency cannot disappear
ans-b

Q18 THE DIFFERENCE B/W PHASE N FREQUENCY MODULATION
(a)is purely theoretical because they are same in practice
(b)ia too great to make the two system compatible
(c)lies in the poorer audio response of phase modulation
(d)lies in different definitions of the modulation index
ans-d



Q19 AN FM SIGNAL WITH MODULATION INDEX m IS PASSED THROUGH A FREQUENCY TRIPLER THE WAVE IN THE O/P OF THE TRIPLER WIILL HAVE A MODULATION INDEX OF
(A)m/3
(b)m
(c)3m
(d)9m
ans-c

Q20 AN FM, SIGNAL WITH DEVIATION "a" IS PASSED THROUGH A MIXER N HAS ITS FREQUENCY REDUCED 5 FOLD .THE DEVIATION IN THE O/P OF THE MIXER IS
(a)5a
(b)indeterminate
(c)a/5
(d)a
ans-d

Q21 A PRE EMPHASIS CIRCUIT PROVIDES EXTRA NOISE IMMUNITY BY
(a)boosting the base frequency
(b)amplifying the higher audio frequency
(c)pre amplifying the whole audio band
(d)converting the pm to fm
ans-b

Q22 SINCE NOISE PM THE FM WAVE ,AS THE NOISE SIDEBAND FREQUENCY APPROACHES THE CARRIER FREQUENCY ,THE NOISE AMPLITUDE
(a)remains constant
(b)decreases
(c)increases
(d)is equalised
ans-b

Q23 WHEN THE MODULATING FREQUENCY IS DOUBLED ,THE MODULATION INDEX IS HALVED AND THE MODULATING VOLTAGE IS REMAINS CONSTANT,THE MODULATION SYSTEM IS
(a)am
(b)pm
(c)fm
(d)any of the three
ans-c

Q24 INDICATE WHICH OF THE FOLLOWING IS NOT AN ADVANTAGE OF FM OVER AM
(a)better noise immunity is provided
(b)lower bandwidth is required
(c)the transmitted power is more useful
(d)less modulating power is required
ans-b

Q25 ONE OF THE FOLLOWING IS INDIRECT WAY OF GENERATING FM IS THE
(a)reacatnce fet modulator
(b)varactor diode modulator
(c)armstrong method
(d)reactance bipolar transistor modulator
ans-c

Q26 IN AN FM STEREO MULTIPLEXING TRANSMISSION ,THE
(a)sum signal modulates the 19 khz sun carrier
(b)difference signal modulates the 19 khz sub carrier
(c)difference signal modulates 38 khz sub carrier
(d)difference signal modulates 67 khz sub carrier
ans-c

Q27 INDICATE WHICH OF THE FOLLOWING STATEMENTS ABOUT THE ADVANTAGE OF THE PHASE DISCRIMINATOR OVER THE SLOPE DETECTOR IS FALSE
(a)much easier alignment
(b)better linearity
(c)greater limiting
(d)fewer tuned circuit
ans-c

Q28 SHOW WHICH OF THE FOLLOWING STATEMENTS ABOUT THE AMPLITUDE LIMITER IS UNTRUE
(a)the circuit is always biased in class c ,by virtue of leak-type bias.
(b)when i/p increases past the threshold limiting the gain decreases to keep the o/p constant
(c)the o/p must be tuned
(d)leak type bias must be used
ans-a

Q29 IN A RADIO RECEIVER WITH SIMPLE AGC
(a)an increase in signal strength produces more agc
(b)the audio stage gain is normally controlled by the agc
(c)the faster the agc time constant ,the more accurate the o/p
(d)the highest agc voltage is produced b/w stations
ans-a

Q30 IN A BROADCAST SUPERHETRODYNE RECEIVER ,THE
(a)local oscillator operates below the signal frequency
(b)mixer i/p must be tuned to the signal frequency
(c)local oscillator frequency is normally doubled the if
(d) rf amplifier normally works at 455 khz above the carrier
ans-b

Q31 TO PREVENT OVER LOADING OF THE LAST IF AMPLIFIER IN A RECEIVER ,ONE SHOULD USE
(A)squelch
(b)variable sensitivity
(c)variable selectivity
(d)double conversion
ans-b

Q32 IN A RATIO DETECTOR
(a)the linearity is worse than in a phase discriminator
(b)stabilisation against signal strength variation is provided
(c)the o/p is twice obtainable from a similar phase discriminator
(d)the circuit is same as in a discriminator ,except that the diodes are reversed
ans-a

Q33 THE TYPICAL SQUELACH CIRCUIT
(a)cuts off an audio amplifier when the carrier is absent
(b)eliminates the rf interference when the signsl is weak.
(c)cuts off an amplifier when the agc is maximum
(d)cuts off an amplifier when the agc is minimum
ans-a

Q34 INDICATE THE FALSE STATEMENT IN CONNECTION WITH COMMUNICATION RECEIVERS
(a),the noise limiter cuts off the receiver's o/p during a noise pulse
(b)a product demodulator could be used for the reception of morse code
(c)double conversions is used to improve image rejection
(d)variable sensitivity is used to eliminate selective fading
ans-d

Q35 THE CONTROLLED OSCILLATOR SYNTHESIZER IS SOMETIMES PREFFERED TO THE DIRECT ONE BECAUSE
(a)it is a simpler piece of instrument
(b)it's frequency stability is better
(c)it does not require crystal oscillator
(d)it is relatively free of spurious noise
ans-d
Q35 THE FREQUENCY GENERATED BY EACH DECADE IN A DIRECT FREQUENCY SYNTHESIZER IS MUCH HIGHER THAN THE FREQUENCY SHOWN,THIS DONE TO
(A)reduce the spurious frequency problem
(b)increase the frequency stability of the synthesizer
(c)reduce the number of decades
(d)reduce the number of crystal required
ans-a

Q36 INDICATE WHICH OF THE FOLLOWING CAN'T DEMODULATE SSB SIGNAL
(a)balanced modulator
(b)product modulator
(c)bfo
(d)phase discriminator
ans-d

Q37 IF AN AMPLIFIER IS USED AS THE FIRST AF AMPLIFIER IN A TRANSISTOR RECEIVER ,THIS WILL HAVE THE EFFECT OF
(a)improving the effectiveness of the agc
(b)reducing the effect of -ve peak clipping
(c)reducing the effect of noise at low modulation depths
(d)improving the selectivity of the receiver
ans-b

Q38 THE IMAGE FREQUENCY OF AN SUPERHETRODYNE RECEIVER IS
(a)is created within the receiver it self
(b)is due to insufficient adjacent channel rejection
(c)is not rejected by if tuned circuits
(d)is independent of the frequency at which the receiver is tuned
ans-c

Q39 ONE OF THE MAIN FUNCTION OF THE RF AMPLIFIER IN SUPERHETRODYNE RECEIVER IS TO
(a)provide improve tracking
(b)permit better adjacent channel rejection
(c)increase the tuning range of the receiver
(d)improve the rejection of the image frequency
ans-d

Q40 A RECEIVER HAS POOR IF SELECTIVITY.IT WILL THEREFORE ALSO HAVE POOR
(a)blocking
(b)double-spotting
(c)diversity reception
(d)sensitivity
ans-a

Q41 THREE POINT TRACKING IS ACHIEVED WITH
(a)variable selectivity
(b)the padder capacitor
(c)double spotting
(d)double conversion
ans-b

Q42 THE LOCAL OSCILLATOR OF A BROAD CAST RECEIVER IS TUNED TO O FREQUENCY HIGHER THAN THE INCOMING FREQUENCY
(a)to help the image frequency rejection
(b)to permit easier tracking
(c)because otherwise an intermediate frequency could not be produced
(d)to allow adequate frequency coverage without switching
ans-d

Q43 A LOW RATIO OF THE AC TO THE DC LOAD IMPEDANCE OF A DIODE DETECTOR RESULTS IN
(a)diagonal clipping
(b)poor agc operation
(c)-ve peak clipping
(d)poor af response
ans-c

Q44 THE INTERMEDIATE FREQUENCY IS VERY HIGH(INDICATE FALSE STATEMENT)
(a)image frequency rejection is very good
(b)the local oscillator need not be extremely stable
(c)the selectivity Will be poor
(d)tracking will be improved
ans-d

Q45 WHEN A RECEIVER HAS A GOOD BLOCKING PERFORMANCE ,THIS MEANS THAT
(a)it does not suffer from double spotting
(b)it's image frequency rejection is poor
(c)it is unaffected by agc derived from near by transmission
(d)it's detector suffers from burnout
ans-c

Q46 INDICATE THE FALSE STATEMENT.THW SWR ON A TRANSMISSION LINE IS INFINITY ,THE LINE IS TERMINATED IN
(A)a short circuit
(b)a complex impedance
(c)an open circuit
(d)a pure reactance
ans-b

Q47 A(75-J50)ohm IS CONNECTED TO A COAXIAL LINE OF Z0=75 ohm AT 10GHZ .THE BEST WAY OF MATCHING CONSISTS IN CONNECTING
(a)a short circuit stab at the load
(b)an inductance at the load
(c)a capacitance at some specific distance from the load
(d)a short circuit stab at some specific distance from the load
ans-d

Q48 THE VELOCITY FACTOR OF A TRANSMISSION LINE
(a)depends on the dielectric constant of the material used
(b)increases the velocity along the transmission line
(c)is governed by skin effect
(d)is higher for a solid dielectric than for air
ans-a

Q49 IMPEDANCE INVERSION MAY BE OBTAINED WITH
(A)a short ckt stub
(B)an open ckt stub
(c)a quarter wave line
(d)a half wave line
ans-c

Q50 SHORT CKT STUBS ARE PREFERRED TO OPEN CKT STUBS BECAUSE THE LATER ARE
(a)more difficult to make n connect
(b)made of transmission line of different characteristics impedance
(c)liable to radiate
(d)incapable of giving full range of reactances
ans-c

Q51 FOR TRANSMISSION LINE LOAD MATCHING OVER A RANGE OF FREQUENCIES ,IT IS BEST TO USE A
(A)balun
(b)broadband directional coupler
(c)double stab
(d)single stub of adjustable position
ans-c

Q52 THE MAIN DISADVANTAGE OF THE TWO HOLE DIRECTIONAL COUPLER IS
(A)low directional coupling
(b)poor directivity
(c)high swr
(d) narrow bandwidth
ans-d

Q53 TO COUPLE A COAXIAL LINE TO A PARALLEL-WIRE ,IT IS BEST TO USE A
(a)slotted line
(b)balun
(c)directional coupler
(d)quarter wave transformer ans-b

Q54 INDICATE WHICH OF THE FOLLOWING TERM APPLIES TO TROPOSCATTER PROPAGATION
(a)sids
(b)fading
(c)atmospheric storm
(d)Faraday rotation
ans-b

Q55 VLF WAVES ARE USED FOR SOME TYPES OF SERVICES BECAUSE
(a)of the low power required
(b)the transmitting antennas are of convenient size
(c)they r very reliable
(d)they penetrate the ionosphere easily
ans-c

Q56 HIGH FREQUENCY WAVES ARE
(a)absorbed by the f2 layer
(b)reflected by the d layer
(c)capable of use for long distance communication on the moon
(d)are affected by solar cycle
abs-d

Q57 DISTANCE'S NEAR THE SKIP DISTANCE SHOULD BE USED FOR SKY WAVE PROPAGATION
(A)to avoid titting
(b)to prevent sky wave and upper ray interference
(c)to avoid faraday effect
(d)so as not to exceed the cricticial frequency
ans-b

Q58 A SHIP TO SHIP COMMUNICATION PLAGNUED BY FADING .THE BEST SOLUTION SEEMS TO BE THE USE OF
(a)a more directional antenna
(b)a broad band antenna
(c)frequency diversity
(d)space diversity
ans-c

Q59 A RANGE OF MICROWAVE FREQUENCY MORE EASILY PASSED BY THE ATMOSPHERE THAN THE OTHERS IS CALLED A
(A)window
(b)critical frequency
(c)gyro frequency range
(d)resonance in atmosphere
ans-a

Q60 FREQUENCY IN UHF RANGE NORMALLY PROPAGATE BY MEANS OF
(a)ground wave
(b)sky wave
(c)surface wave
(d)space wave
ans-d

Q61 TROPOSPHERIC SCATTER IS USED WITH FREQUENCY IN THE FOLLOWING RANGE
(a)hf
(b)vhf
(c)uhf
(d)vlf
ans-c

Q62 THE GROUND WAVES EVENTUALLY DISAPPEARS ,AS ONE MOVES AWAY FROM THE TRANSMITTER BECAUSE OF
(a)interference from the sky wave
(b)loss of los condition
(c)maximum single hop distance limitation
(d)tilting
ans-d

Q63 IN EM WAVES ,POLARISATION
(a)is caused by reflection
(b)is due to inverse nature of the waves
(c)result from the longitudinal nature of the waves
(d)is always vertical in an isotropic medium
ans-b

Q64 AN EM WAVE TRAVELS IN THE FREE SPACE ONLY ONE OF THE FOLLOWING CAN HAPPEN TO THEM
(a)absorption
(b)attenuation
(c)refraction
(d)reflection
ans-b

Q65 THE ABSORPTION OF RADIO WAVES BY THE ATMOSPHERE DEPENDS ON
(a)their frequency
(b)their distance from the transmitter
(c)the polarisation of the wave
(d)the polarisation of the atmosphere
ans-a

Q66 EM WAVES ARE REFRACTED WHEN THEY
(a)pass in to medium of different dielectric constants
(b)r polarised at right angles to the direction of propagation
(c) encounter a perfectly conducting surface
(d)pass through a small slot in a conducting plane
ans-a

Q67 DIFFRACTION OF EM WAVES
(a)is caused by reflections from the ground
(b)arises only with spherical wave fronts
(c)will occur when the waves pas through a large slot
(d)may occur around the edges of a sharp obstacle
ans-d

Q68 WHEN MW SIGNALS FOLLOW THE CURVATURE OF THE EARTH ,THIS IS KNOWN AS
(a)the Faraday effect
(b)ducting
(c)tropospheric scatter
(d)ionospheric reflection
ans-b

Q69 HELICAL ANTENNA R OFTEN USED FOR SATELLITE TRACKING AT VHF DUE TO
(a)troposcatter
(b)superrefraction
(c)ionospheric refraction
(d)the faraday effect
ans-d

Q70 AN UNGROUNDED ANTENNA NEAR THE GROUND
(a)acts as a single antenna of twice the height
(b)is unlikely to need an earth mat
(c)acts as an antenna array
(d)must be horizontally polarised
ans-c

Q71 ONE OF THE FOLLOWING CONSISTS OF NON RESONANT ANTENNAS
(a)the rhombic antenna
(b)the folded dipole
(c)the end fire array
(d)the broad side array
ans-a

Q72 ONE OF THE FOLLOWING IS VERY USEFUL AS A MULTI BAND HF RECEIVING ANTENNA.THIS IS THE
(A)conical horn
(b)folded dipole
(c)log periodic
(d)square loop
ans-c

Q73 WHICH OF THE FOLLOWING ANTENNA IS BEST EXCITED FROM A WAVE GUIDE?
(a)biconical
(b)horn
(c)helical
(d)discone
ans-b

Q74 INDICATE THE ANTENNA THAT IS NOT WIDEBAND
(a)dicone
(b)folded dipole
(c)helical
(d)marconi
ans-d

Q75 WHICH ONE OF THE FOLLOWING IS NOT APPLY TO THE YAGI UDA ANTENNA
(a)good bandwidth
(b)parasitic elements
(c)folded dipole
(d)high gain
ans-d

Q76 AN ANTENNA THAT IS CIRCULARLY POLARISED IS the
(a)helical
(b)small circular loop
(c)parabolic reflector
(d)yagi uda
ans-a

Q77 THE STANDARD REFERENCE ANTENNA FOR THE DIRECTIVE GAIN IS THE
(a)infinitesimal dipole
(b)isotropic antenna
(c)elementary doublet
(d)half wave dipole
ans-b

Q78 TOP LOADING IS DONE WITH AN ANTENNA IN ORDER TO INCREASE ITS
(a)effective height
(b)bandwidth
(c)beam width
(d)i/p capacitance
ans-a

Q79 CASSEGRAIN FEED IS USED WITH A PARABOLIC REFLECTOR TO
(a)increase the gain of the system
(b)increase the beamwith of the system
(c)reduce the size of the main reflector
(d)allow the feed to be placed at a convenient point
ans-d

Q80 ZONING IS USED WITH A DIELECTRIC ANTENNA IN ORDER TO
(a)reduce the bulk of the lens
(b)increase the bandwidth of the lens
(c)permit point to point focusing
(d)correct the curvature of the wavefront from a horn that is too short
ans-a

Q81 A HELICAL ANTENNA IS USED IN SATELLITE TRACKING BECAUSE OF ITS
(a)circular polarisation
(b)maneuverability
(c)broad bandwidth
(d)good front to back ratio
ans-a

Q82 THE DISCONE ANTENNA IS
(a)a useful direction finding antenna
(b)used as a radar receiving antenna
(c)circularly polarised like other circular antennas
(d)useful as a uhf receiving antenna
ans-d

Q83 ONE OF THE FOLLOWING IS NOT A OMNIDIRECTIONAL ANTENNA
(a)half wave dipole
(b)log-pereodic
(c)discone
(d)marconi
ans-b

Q84 WHEN EM WAVE ARE PROPAGATED IN A WAVEGUIDE
(a)they travel along the broader walls of the guide
(b)the reflected from the wall but do not travel along them
(c)they travel through the dielectric without touching the wall
(d)they travel along all 4 walls of the waveguide
ans-b

Q85 WAVEGUIDES R USED MAINLY FOE MICROWAVE SIGNALS BECAUSE
(a)they depend on straight line propagation which applies to microwaves only
(b)losses would be too heavy at lower frequencies
(c)there are no generators powerful enough to excite them at lower frequency
(d)they would be too bulky at lower frequency
ans-d

Q86 THE WAVELENGTH OF A WAVE IN A WAVEGUIDE
(a)is greater than in free space
(b)depends only on the waveguide dimensions and the free space wavelength
(c)is inversely proportional to the phase velocity
(d)is directly proportional to the group velocity
ans-a

Q87 COMPARED WITH THE EQUIVALENT TRANSMISSION LINES ,3GHZ WAVEGUIDES(INDICATE FALSE STATEMENT)
(a)r less lossy
(b)can carry high powers
(c)r less bulky
(d)have lower attenuation
ans-c

Q88 WHEN A PARTICULAR MODE IS EXCITED IN A WAVEGUIDE ,THERE APPEARS AN EXTRA ELECTRIC COMPONENT IN THE DIRECTION OF PROPAGATION.THE RESULTING MODE IS
(a)transverse electric
(b)transverse magnetic
(c)longitudinal
(d)transverse electromagnetic
ans-b

Q89 WHEN EM WAVES ARE REFLECTED AT AN ANGLE FROM A WALL,THEIR WAVELENGTH ALONG THE WALL IS
(a)same as in free space
(b)the same as the wavelength perpendicular to the wall
(c)shorter because of the doppler effect
(d)greater in the actual direction of propagation
ans-d

Q90 AS A RESULT OF REFLECTIONS FROM A PLANE CONDUCTING WALL ,EM WAVES ACQUIRE AN APPARENT VELOCITY GREATER THAN THE VELOCITY OF LIGHT IN SPACE.THIS IS CALLED THE
(a)velocity of propagation
(b)normal velocity
(c)group velocity
(d)phase velocity
ans-d

Q91 INDICATE THE FALSE STATEMENT .WHEN THE FREE SPACE WAVELENGTH OF A SIGNAL EQUALS THE CUTOFF WAVELENGTH OF THE GUIDE
(a)the group velocity becomes zero
(b)phase velocity becomes infinite
(c)the characteristic impedence of the guide becomes infinite
(d)the wavelength within the waveguide becomes infinite
ans-c

Q92 THE DOMINANT MODE OF PROPAGATION IS PREFERRED WITH RECTANGULAR WAVE GUIDES BECAUSE(INDICATE THE FALSE STATEMENT)
(a)it leads to the smallest waveguide dimensions
(b)it resulting impedance can be matched directly to coaxial lines
(c)it is easier ti exite than the other modes
(d)propagation of it without any spurious generation can be ensured
ans-b

Q93 A CHOCKE FLANGE MAY BE USED TO COUPLE TW WAVEGUIDES
(a)to help in alignment of the waveguides
(b)because it is simpler than any other join
(c)to compensate for discontinuity at the join
(d)to increase the bandwidth of the system
ans-c

Q94 IN ORDER TO COUPLE TWO GENERATORS TO A WAVEGUIDE SYSTEM WITHOUT COUPLING THEM TO EACH OTHER ,ONE COULD NOT USE A
(a)rat race
(b)e plane t
(c)hybrid ring
(d)magic t
ans-b

Q95 WHICH OF THE FOLLOWING WAVEGUIDE TUNING IS NOT EASILY ADJUSTABLE
(a)screw
(b)stub
(c)iris
(d)plunger
ans-c

Q96 A PISTON ATTENUATOR IS A
(a)vane attenuator
(b)waveguide below cutoff
(c)mode filter
(d)flap attenuator
ans-b

Q97 CYLINDRICAL CAVITY RESONATOR R NOT USED WITH KLYSTRON BECAUSE THEY HAVE
(a)a q taht is too low
(b)a shape whose resonant frequency is too difficult to calculate
(c)harmonically related resonant frequency
(d)too heavy looses
ans-c

Q98 A DIRECTIONAL COUPLER WITH THREE OR MORE HOLES IS SOMETIMES PREFERRED TO TWO HOLE COUPLER
(a)because it is more efficient
(b)to increase coupling of the signal
(c)to reduce spurious mode generation
(d)to increase the bandwidth of the system
ans-d

Q99 A FERRITE IS
(a)a nonconductor with magnetic properties
(b)an inter metallic compound with particularly good conductivity
(c)an insulator with heavily attenuates magnetic fields
(d)a microwave semiconductor invented by faraday
ans-a

Q100 A MANGANESE FERRITE MAY BE USED AS A (INDICATE FALSE STATEMENT)
(a)circulator
(b)isolator
(c)garnet
(d)phase shifter
ans-c
Q101 THE MAXIMUM POWER THAT CAN BE HANDLED BY A FERRITE COMPONENT IS LIMITED BY
(a)curie temperature
(b)saturation magnetization
(c)line width
(d)gyromagnetic resonance
ans-a

Q102 A PIN DIODE IS
(A)a metal semiconductor point contact diode
(b)a microwave mixer diode
(c)often used as a microwave detector
(d)suitable for use as a microwave switch
ans-d

Q103 A DUPLEXER IS USED
(a)to couple two different antennas to a transmitter without mutual interference
(b)to allow the one antenna to be used for reception or transmission without mutual interference
(c)to prevent interference b/w two antennas when they are connected to a receiver
(d)to increases the speed of the pulses in a pulsed radar
ans-b

Q104 FOR SOME APPLICATION CIRCULAR WAVEGUIDE MAY BE PREFERRED OVER RECTANGULAR ONE BECAUSE OF
(a)the smaller cross section needed at any frequency
(b)lower attenuation
(c)freedom from spurious modes
(d)rotation of polarisation
ans-b

Q105 INDICATE WHICH OF THE FOLLOWING CANNOT BE FOLLOWED BY THE WORD WAVEGUIDE
(a)elliptical
(b)flexible
(c)coaxial
(d)ridged
ans-c

Q106 IN ORDER TO REDUCE CROSS SECTIONAL DIMENSIONS,THE WAVEGUIDE TO USE IS
(a)circular
(b)ridged
(c)rectangular
(d)flexible
ans-b

Q107 FOR LOW ATTENUATION BEST TRANSMISSION MEDIUM IS
(a)flexible waveguide
(b)ridged waveguide
(c)rectangular waveguide
(d)coaxial line
ans-c

Q108 A MICROWAVE TUBE AMPLIFIER USES AN AXIAL MAGNETIC FIELD AND A RADIAL ELECTRIC FIELD .THIS IS A
(a)reflex klystron
(b)coaxial magnetron
(c)travelling wave magnetron
(d) cfa
ans-d

Q109 ONE OF THE FOLLOWING IS UNLIKELY TO BE USED AS A PULSED DEVICE.IT IS A
(a)multicavity klystron
(b)bandwidtho
(c)cfa
(d)twt
ans-b

Q110 ONE OF THE REASON WHY VACCUM TUBES EVENTUALLY FAIL AT MICROWAVE FREQUENCIES IS THAT THEIR
(a)nf increase
(b)transit time become too short
(c)shunt capacitive reactances become too large
(d)series inductive reactances become too small
ans-a

Q111 INDICATE THE FALSE STATEMENT .TRANSIT TIME IN MICROWAVE TUBE WILL BE REDUCED IF
(a)the electrodes are brought together
(b)a higher anode current is used
(c)multiple or coaxial leads r used
(d)the anode voltage is made large
ans-c

Q112 THE MULTICAVITY KLYSTRON
(a)is not a good low level amplifier because of noise
(b)has a high repeller voltage to ensure a rapid transit time
(c)is not suitable for pulsed operation
(d)needs a long transit time through the buncher cavity to ensure current modulation
ans-a

Q113 INDICATE THE FALSE STATEMENT.KLYSTRON AMPLIFIERS MAY USE INTERMEDIATE CAVITIES TO
(a)prevent the oscillations that occurs in two cavity klystron
(b)increase the bandwidth
(c)improve the power gain
(d)increase the efficiency of the klystron
ans-a

Q114 THE TWT IS SOMETIMES PREFERRED TO THE MULTICAVITY KLYSTRON AMPLIFIER ,BECAUSE THE FORMAR
(a)is more efficient
(b)has a greater bandwidth
(c)has a higher number of modes
(d)produses a higher o/p power
ans-b

Q115 THE TRANSIT TIME IN THR REPELLER SPACE OF A REFLEX KLYSTRON MUST BE N+3/4 CYCLE TO ENSURE THAT
(a)electrons r accelerated by the gap voltage on their return
(b)returning electrons gives energy to rhe gap oscillations
(c)it is equal to the period of the cavity oscillations
(d)the repeller is not damaged by stricking electrons
ans-b

Q116 THE CAVITY MAGNETRON USE STRAPPING TO
(a)prevent mode jumping
(b)prevent cathod back heating
(c)ensure bunching
(d)improve the phase focusing
ans-a

Q117 A MAGNETIC FIELD IS USED IN THE CAVITY MAGNETRON TO
(a)prevent anode current in the absence of oscillations
(b)ensure that the oscillations r pulsed
(c)help in focusing the electron beam,thus preventing spreading
(d)ensure that the electrones will orbit around the cathod
ans-d

Q118 TO AVOID DIFFICULTIES WITH STRAPPING AT HIGH FREQUENCYS,THE TYPE OF CAVITY STRUCTUER USED IN THE MAGNETRON IS THE
(A)HOLE AND SLOT
(b)slot
(c)vane
(d)rising sun
ans-d

Q119 THE PRIMARY PURPOSE PF THE HELIX IN THE TWT IS
(a)prevent the electron beam spreading in the long tube
(b)reduce axial velocity of the rf field
(c)ensure broadband operation
(d)reduce the noise figure
ans-b

Q120THE ATTENUATOR IN THE TWT IS USED FOR
(a)help focusing
(b)prevent oscillations
(c)prevent saturatuion
(d)increase gain
ans-b

Q121 PERIODIC PERMANENT MAGNET FOCUSING IS USED WITH TWT TO
(a)allow pulsed operation
(b)improve electron bunching
(c)avoid the bulk of an electromagnet
(d)allow coupled cavity operation at the high frequency
ans-c

Q122 THE TWT IS SOMETIMES PREFERRED TO THE MAGNETRON AS A RADAR TRANSMITTER O/P TUBE BECAUSE IT IS
(a)capable of longer duty cycle
(b)a more efficient amplifier
(c)more broadband
(d)less noise
ans-a

Q123 A MAGNETRON WHOSE OSCILLATING FREQUENCY IS ELECTRONICALLY ADJUSTABLE OVER A WIDE RANGE IS CALLED
(a)coaxial magnetron
(b)ditcher tuned magnetron
(c)frequency agile magnetron
(d)vtm
ans-d

Q124 INDICATE WHICH OF THEE FOLLOWING IS NOT A TWTY SLOW WAVE STRUCTURE
(a)periodic permanent magnet
(b)coupled cavity
(c)helix
(d)ring bar
ans-a

Q125 THE GLASS TUBE OF A TWT MAY BE COATED WITH AQUADAG TO
(a)help focusing
(b)provide attenuation
(c)improve bunching
(d)increse gain
ans-b

Q126 A BACKWARD WAVE OSCILLATOR IS BASED ON THE
(a)rising sun magnetron
(b)cross field amplifier
(c)coaxial magnetron
(d)travelling wave tube
ans-d

Q127 A PARAMATRIC AMPLIFIER MUST BE COOLED
(a)because paramatric amplifications generates a lot of heat
(b)to increase bandwidth
(c)because it cannot operate at room temp
(d)to improve the noise performance
ans-d

Q128 A RUBY MASER AMPLIFIER MUST BE COOLED
(a)because maser amplifiers generats a lot of heat
(b)to increase bandwidth
(c)because it can not operate at room temp
(d)to improve the noise performance
ans-c

Q129 THE TRANSMISSION SYSTEM USING TWO GROUND PLANES IS
(a)microstrip
(b)elliptical waveguide
(c)parallel wire line
(d)stripline
ans-d

Q130 INDICATE THE FALSE STATEMENT.AN ADVANTAGE OF USING STTRIPLINE OVER WAVVGUIDE IS its
(a)smaller bulk
(b)greater bandwidth
(c)higher power handling capability
(d)greater compatibility with solid state device
ans-c

Q131 INDICATE THE FALSE STATEMENT.AN ADVANTAGE OF USING STRIPLINE OVER MICROSTRIPLINE IS ITS
(a)easier integration with semiconductor devices
(b)lower tendency to radiate
(c)higher isolation b/w ajacent ckts
(d)higher q
ans-a

Q132 SURFACE ACOUSTIC WAVE PROPAGATE IN
(a)gallium arsenide
(b)indium phosphste
(c)stripline
(d)quartz crystal
ans-d

Q133 SAW DEVICES MAY BE USED AS
(a)transmission media like stripline
(b)filters
(c)uhf amplifiers
(d)oscillator at milimiter frequency
ans-b

Q134 INDICATE THE FALSE STATEMENT.FET'S R PREFERRED TO BIPOLAR TRANSISTOR AT THE HIGHEST FREQUENCIES BECAUSE THEY ARE
(a)less noisy
(b)lend themselves more readily to integration
(c)are capable of higher efficiencies
(d)can provide higher gain
ans-b

Q135 THE BIGGEST ADVANTAGE OF THE TRAPATT DIODE OVER THE IMPATT DIODE IS IT'S
(a)lower noise
(b)higher efficiency
(c)ability to operate at higher frequency
(d)lesser sensitivity to harmonics
ans-b

Q136 INDICATE WHICH OF THE FOLLOWING DIODE WILL PRODUCE THE HIGHEST PULSED POWER O/P
(a)varactor
(b)gunn
(c)schottky diode
(d)rimpatt diode
ans-d

Q137 INDICATE WHICH OF THE FOLLOWING DIODE DOES NOT USES -VE RESISTANCE IN IT'S OPERATION
(a)backward
(b)gunn
(c)impatt
(d)tunnel
ans-a

Q138 ONE OF THE FOLLOWING IS NOT USED AS A MICROWAVE MIXER OR DETECTOR
(a)crystal diode
(b)schottky barrier diode
(c)backward diode
(d)pin diode
ans-d

Q139 ONE OF THE FOLLOWING MICROWAVE DIODE IS SUITABLE FOR VERY LOW POWER OSCILLATOR ONLY
(a)tunnel
(b)avalanche
(c)gunn
(d)impatt
ans-a

Q140 THE TRANSFERRED-ELECTRON BULK EFFECT OCCURS IN
(a)germenium
(b)gallium arsenide
(c)silicon
(d)metal semiconductor junctions
ans-b

Q141 THE GAIN BANDWIDTH FREQUENCY OF A MICROWAVE TRANSISTOR,is THE FREQUENCY AT WHICH
(a)alpha of the transistor falls by 3db
(b)beta of the transistor falls by 3 db
(c)power gain of the transistor falls to unity
(d)beta of the transistor falls to unity
ans-d

Q142 A VARACTOR DIODE MAY BE USEFUL AT MICROWAVE FREQUENCY(INDICATE THE FALSE STATEMENT)
(A)for electronic tunning
(b)for frequency multiplication
(c)as an oscillator
(d)as a paramatric amplifier
ans-c

143 FOR A MICROWAVE TRANSISTOR TO OPERATE AT THE HIGHEST FREQUENCY(INDICATE THE FALSE STATEMENT)
(a)collector voltage must be large
(b)collector current must be large
(c)base should be thin
(d)emitter area must be large
ans-d

Q144 IF HIGH ORDER FREQUENCY MULTIPLICATION IS REQUIRED FROM A DIODE MULTIPLIER
(a)the resestive cutoff frequency must be high
(b)a small value of base resistance is required
(c)a step recovery diode must be used
(d)a large range of capacitance variation is needed
ans-c

Q145 TRAVELLING WAVE PARAMATRIC AMPLIFIER ARE USED TO
(a)provide a greater gain
(b)reduce the number of varactor diode required
(c)avoid the need of coupling
(d)provide a greater bandwidth
ans-d

Q146 A PARAMATRIC AMPLIFIER SOMETIMES USES A CIRCULATOR TO
(a)prevent noise feedback
(b)allow antenna to be used simultaneously for transmission and reception
(c)seperate the signal and idler frequency
(d)permit more efficient pumping
ans-a

Q147 THE NON DEGENERATED ONE PORT PARAMATRIC AMPLIFIER SHOULD HAVE A HIGH RATIO OF PUMP TO SIGNAL FREQUENC BECAUSE THIS
(a)permits satisfactory high frequency operation
(b)yields a low nf
(c)reduces pump power required
(d)permits satisfactory low frequency operation
ans-b

Q148 THE TUNNEL DIODE
(a)has a tiny hole through it's center to facilitate tunneling
(b)ia a point contact diode with a very high reverse resistance
(c)uses a high doping level to provide a narrow junction
(d)works by quantam tunneling exhibited by gallium arsenide only
ans-c

Q149 A TUNNEL DIODE IS LOSELY COUPLED TO IT'S CAVITY IN ORDER TO
(a)increase the frequency stability
(b)increase the available -ve resistance
(c)faciliting tunning
(d)allow operation at the high frequency
ans-a

Q150 THE -VE RESISTANCE IN A TUNNEL DIODE
(a)is amximum at the peak point of the characteristics
(b)is available b/w peak n vally point
(c)is maximum at valley point
(d)may be improved by use of reverse bias
ans-b
151 THE BIGGEST ADVANTAGE OF GALLIUM ANTIMONIDE OVER GERMANIUM FOR TUNNEL DIODE USE IS THAT FORMER HAS A
(a)lower noise
(b)higher ion mobility
(c)larger voltages swing
(d)simpler fabrication process
ans-c

Q152 -VE RESISTANCE IS OBTAINED WITH A GUNN DIODE BECAUSE OF
(a)electron transfer to less mobile energy level
(b)avalanche breakdown with the high voltage gradient
(c)tunneling across the junction
(d)electron domains forming the junction
ans-a

Q153 FOR GUNN DIODES,GaAs IS PREFERRED TO SILICON BECAUSE THE FORMER
(a)has a suitable empty energy band,which silicon does not have
(b)has a higher ion mobility
(c)has a lower noise at the highest frequency
(d)is capable of handling higher power densities
ans-a

Q154 THE BIGGEST DISADVANTAGE OF THE IMPATT DIODE IS IT'S
(a)lower efficiency than that of the other microwave diode
(b)high noise
(c)inability to provide pulsed operation
(d)low power handling ability
ans-b

Q155 THE MAGNETIC FIELD IS USED WITH A RUBY MASER TO
(a)provide sharp focusing for the electron beam
(b)increase the population inversion
(c)allow room temp operation
(d)provide frequency adjustment
ans-d

Q156 THE RUBY MASER HAS BEEN PREFERRED TO THE AMMONIA MASER FOR MICROWAVE AMPLIFICATION,BECAUSE THE FORMER HAS
(a)a much greater bandwidth
(b)a better frequency stability
(c)a lower noise figure
(d)no need for a circulator
ans-a

Q157 A PARAMETRIC AMPLIFIERS AND MASERS ARE SIMILAR TO EACH OTHER IN THAT(INDICATE FALSE STATEMENT)
(a)must have pumping
(b)r extremely low noise amplifiers
(c)must be cooled down to a few kelvins
(d)generally require circulators,since they r one port devices
ans-c

Q158 A MASER RF AMPLIFIER IS NOT REALLY SUITABLE FOR
(A)radioastronomy
(b)satellite communications
(c)radar
(d)troposcatters receivers
ans-c

Q159 THE RUBY LASER DIFFERS FROM THE RUBY MASERS IN THAT THE FORMER
(a)does not require pumping
(b)needs no resonator
(c)is an oscillator
(d)produces much lower power
ans-c

Q160 THE O/P FROM A LASER IS MONOCHROMATIC ,THIS MEANS THAT
(a)infrared
(b)polarised
(c)narrow beam
(d)single frequency
ans-d

Q161 FOR A GIVEN AVG POWER ,THE PEAK POWER O/P POWER OF A RUBY LASER MAY BE INCREASED BY
(a)using cooling
(b)using q spooling
(c)increasing the magnetic field
(d)dispensing with the fabry-perot lasers
ans-b

Q162 COMMUNICATIONS LASERS R USED WITH OPTICAL FIBERS,RATHER THAT IN OPEN LINKS,TO
(a)ensure that the beam does not spread
(b)prevent atmospheric interference
(c)prevent interference by other lasers
(d)ensure that people are not blinded by them
ans-b

Q163 INDICATE THE FALSE STATEMENT .THE DISADVANTAGES OF SEMICONDUCTOR LASERS OVER LED'S INCLUDE
(a)monochromatic o/p
(b)highest power o/p
(c)lower cost
(d)ability to be pulsed at higher rates
ans-c

Q165 INDICATE WHICH OF THE FALLOWING IS NOT A BINARY NUMBER
(a)morse
(b)baudot
(c)ccitt-2
(d)arq
ans-a

Q166 A SIGNALLING SYSTEM IN WHICH EACH LETTER OF THE ALPHABET IS REPRESENTED BY A DIFFERENT SYMBOL IS NOT USED BECAUSE
(a)it would be too difficult for an operator to memorize
(b)it is redundant
(c)noise would introduce too many errors
(d)too many pulses per letter r required
ans-c

Q167 THE HARTLY LAW STATES THAT
(a)the maximam rate of information transmission depends on the channel bandwidth
(b)the maximam rate of information transmission depends on the on the depth of modulation
(c)reduendancy is essential
(d)only binary codes may be used
ans-a

Q168 INDICATE THE FALSE STATEMENT.IN ORDER TO COMBAT NOISE
(a)the channel bandwidth may be increased
(b)redundancy may be used
(c)the transmitted power may be increased
(d)the signalling rate may be reduced
ans-a

Q169 THE MOST COMMONLY USED MODULATION TECHNIQUE FOR TELEGRAPHY
(a)fsk
(b)two tone modulation
(c)pcm
(d)single tone modulation
ans-a

Q170 PULSE WIDTH MODULATION MAY BE GENERATED
(a)by differentiating pulse position modulation
(b)with monostable multi vibrator
(c)by integrating the signal
(d)with a free running vibrator
ans-b

Q171 INDICATE WHICH OF THE FOLLOWING SYSTEM IS DIGITAL
(a)ppm
(b)pcm
(c)pwm
(d)pulse frequency modulation
ans-b

Q172 QUANTIZING NOISE OCCURS IN
(a)tdm
(b)fdm
(c)pcm
(d)pwm
ans-c

Q173 THE MODULATION SYSTEM INHERENTLY MOST NOISE RESISTANT IS
(a)ssb,suppressed carrier
(b)fm
(c)ppm
(d)pcm
ans-d

Q174 IN ORDER TO REDUCE QUANTIZING NOISE ONE MUST
(a)increase the number of standard amplitudes
(b)send pulses whose sides r nearly vertical
(c)use an rf amplifier in the receiver
(d)increase number of pulses per second
ans-a

Q175 THE HARTLAY-SHANNON THEOREM SET A LIMIT ON THE
(a)highest frequency that may be sent over a given channel
(b)maximum capacity of a channel with a given noise level
(c)maximum number of coding levels in a channel with a given noise level
(d)maximum number of quantizing levels in a channel of a given bandwidth
ans-b

Q176 INDICATE WHICH OF THE FOLLOWING PULSE MODULATION IS ANALOG
(a)pcm
(b)differential pcm
(c)pwm
(d)delta modulation
ans-c

Q177 COMPANDING IS USED
(a)to overcome quantizing noise in pcm
(b)in pcm transmitters,to allow amplitude limiting in the receivers
(c)to protect small signals in pcm from quantizing distortion
(d)in pcm receivers,to overcome impulse noise
ans-c

Q178 THE BIGGEST DISADVANTAGE OF PCM IS
(a)inability to handle analog signal
(b)the high error rate which it's quantizing noise introduces
(c)incompatibility with tdm
(d)the large bandwidth required
ans-d

Q179 DIGITAL SIGNALS
(a)do not provide a continuous set of value
(b)represent values as a discrete steps
(c)can utilize decimal or binary system
(d)all of the above
ans-d

Q180 THE BAUD RATE IS
(a)always equal to the bit transfer rate
(b)equal to twice the bandwidth of an ideal channel
(c)not equal to the signalling rate
(d)equal to half the bandwidth of an ideal channel
ans-b

Q181 THE SHANNON-HARTELY LAW
(a)refers to distortion
(b)defines bandwidth
(c)describes signaling rates
(d)refers to noise
ans-d

Q182 THE CODE WHICH PROVIDES FOR PARITY CHECKS IS
(a)baudot
(b)ascii
(c)ebcdic
(d)ccitt-2
ans-b

Q183 A FORWARD ERROR CORRECTING CODE CORRECTS THE ERRORS BY
(a)requiring partial retransmission of the signal
(b)require retransmission of the entire signal
(c)requiring no part of the signal to be retransmitted
(d)using parity to correct the errors in all cases
ans-c

Q184 FULL DUPLEX OPERATION
(a)requires two pairs of cables
(b)can transfer data in both direction at once
(c)requires modems at both ends of the circuit
(d)all of the above
ans-d

Q185 THE RS-232 INTERFACE
(a)interconnects data dets and transmission circuit
(b)uses several different connectors
(c)permits custom wiring of signal lines to the connector pins as desired
(d)all of the above
ans-a

Q186 SWITCHING SYSTEMS
(a)improve the efficiency of data transfer
(b)r not used in data system
(c)require additional lines
(d)r limited to small data networks
ans-a

Q189 BROADBAND LONG DISTANCE COMMUNICATION WERE ORIGINALLY MADE POSSIBLE BY THE ADVENT OF
(a)telegraph cables
(b)repeater amplifiers
(c)hf radio
(d)geostationary satellites
ans-b

Q190 THE NUMBER OF REPEATERS ALONG A COAXIAL CABLE LINK DEPENDS ON
(a)whether separates tubes r used for the two directions of transmission
(b)the bandwidth of the system
(c)the number of coaxial cables in the tube
(d)the separation of equalizer
ans-b

Q191 MICROWAVE LINKS REPEATER R TYPICALLY 50 KM APART
(a)because of atmospheric attenuation
(b)because of o/p tybe power limitations
(c)because of the earth's curvature
(d)to ensure that the applied dc voltage is not excessive
ans-c

Q192 MICROWAVE LINKS R GENERALLY PREFERRED TO COAXIAL CABLE FOR TELEVISION TRANSMISSION BECAUSE
(a)they have less overall phase distortion
(b)they r cheaper
(c)of their greater bandwidth
(d)of their relative immunity to impulse noise
ans-a

Q193 ARMORED SUBMARINE CABLE IS USED
(a)to protect the cable at great depths
(b)to prevent inadvertent ploughing-in of the cable
(c)for shallow shore ends of the cable
(d)to prevent insulation breakdown from high feed voltages
ans-c

Q194 A GEOSTATIONARY SATELLITE
(a)is motionless in spce
(b)is not really stationary at all,but orbits the earth within a 24 hr period
(c)appers stationary over the earth's magnetic pole
(d)is located at a height of 35,800 km to ensure global coverage.
ans-b

Q195 INDICATE THE CORRECT STATEMENT REGARDING SATELLITE COMMUNICATIONS
(a)if two earth stations do not face a common satellite,they should communicate via a double satellite hop
(b)satellites r allocatedso that it is impossible for two earth stations not to face the same the same satellite
(c)colocated earth stations r used for frequency diversity
(d)a stellite earth stations must have as many receives chains as they r carriers transmitted to it.
ans-d

Q196 SATELLITES USED FOR INTERNATIONAL COMMUNICATIONS A KNOWN AS
(a)cosmat
(b)dosmat
(c)marisat
(d)intelsat
ans-d

Q197 TELEPHONE TRAFFIC IS MEASURED
(a)with echo cancelers
(b)by relative congestion
(c)in terms of grade of service
(d)in earlangs
ans-d

Q198 IN ORDER TO SEPARATE CHANNELS IN A TDM RECEIVER ,IT IS NECESSARY TO USE
(a)and gates
(b)band pass filter
(c)differentiation
(d)integration
ans-a

Q199 TO SEPARATE FDM RECEIVER,IT IS NECESSARY TO USE
(a)and gates
(b)bpf
(c)differentiation
(d)integration
ans-b

Q200 LOSSES IN OPTICAL FIBERS CAN BE CAUSED BY(INDICATE THE FALSE STATEMENT)
(a)impurities
(b)micro bending
(c)attenuation in the glass
(d)stepped index operation
ans-d

Q201 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
ans-2

Q202 IF THE ANTENNA DIAMETER IN RADAR SYSTEM IS INCREASED BY A FACTOR OF 4,THE MAXIMUM RANGE WILL BE INCREASED BY A FACTOR OF
(a)root 2
(b)2
(c)4
(d)8
ans-c

Q203 IF THE RATIO OF THE ANTENNA DIAMETER TO THE WAVELENGTH IN A RADAR SYSTEM IS HIGH THIS WILL RESULT IN(INDICATE THE FALSE STATEMENT)
(a)large maximum range
(b)good target discrimination
(c)difficult target acqusition
(d)incresed capture area
ans-d

Q204 THE RADAR CROSSECTION OF A TARGET(INDICATE THE FALSE STATEMENT)
(a)depends on the frequency
(b)may be reduced by special coating of the target
(c)depends on the aspect a target ,if this is nonospherical
(d)is equal to the actual cross-sectional area for small targets
ans-d

Q205 FLAT-TOPPED RECTANGULAR PULSE MUST BE TRANSMITTED IN A RADAR TO(INDICATE THE FALSE STATEMENT)
(a)allow a good minimum range
(b)make the return echoes easier to distinguish from noise
(c)prevent frequency changes in the magnetron
(d)allow accurate range measurements
ans-b

Q206 A HIGH PRF (INDICATE THE FALSE STATEMENT)
(a)make the return echoes easier to distinguish from noise
(b)make target tracking easier with conical scaning
(c)increse the maximum range
(d)have no effect on the range resolution
ans-c

Q207 THE IF BANDWIDTH OF A RADAR RECEIVER IS INVERSALY PROPORTIONAL TO THE
(a)pulse width
(b)prf
(c)pulse interval
(d)square root of the peak transmitted frequency
ans-a

Q208 A RETURN ECHO ARRIVES AFTER THE ALLOCATED PULSE INTERVAL
(a)it will interfere with the operation of the transmitter
(b)the receiver may be overloaded
(c)it will not be received
(d)the target will appear closer than it really is
ans-d

Q209 AFTER A TARGET HAS BEEN ACQUIRED ,THE BEST SCANNING SYSTEM FOF TRACKING IS
(a)nodding
(b)spiral
(c)conical
(d)helical
ans-c

Q210 IF THE TARGET CROSS SECTION IS CHANGING ,THE BEST SYSTEM FOR ACCURATE TRACKING IS
(a)lobe switching
(b)sequential switching
(c)conical scanning
(d)monopulse
ans-d

Q211 THE BIGGEST DISADVANTAGE OF CW DOPPLER RADAR IS THAT
(a)it does not give the target velocity
(b)it does not give the target range
(c)a transponder is required at the target.
(d)it does not give the target position
ans-b

Q212 THE A SCOPE DISPLAYS
(a)the target position and range
(b)the target range,but not position
(c)the target position but not range
(d)neither range nor position,but only velocity
ans-b

Q213 THE DOPPLER EFFECT IS USED IN(INDICATE THE FALSE STATEMENT)
(a)moving target plotting on the ppi
(b)the mti system
(c)fm radar
(d)cw radar
ans-a

Q214 THE COHO IN MTI RADAR OPERATES AT THE
(a)intermediate frequency
(b)transmitted frequency
(c)received frequency
(d)pulse repetition frequency
ans-a

Q215 THE FUNCTION OF THE QURTZ DELAY LINE IN AN MTI RADAR IS TO
(a)help in subtracting a complete scan from the previous scan
(b)match the phase of the coho and the stalo
(c)match the phase of the coho and the o/p oscillator
(d)delay a aweep so that the next sweep can be subtracted from it.
ans-a

Q216 A SOLUTION TO THE "BLIND SPEED" PROBLEM IS TO
(a)change the doppler frequency
(b)vary the prf
(c)use monopulse
(d)use mti
ans-b

Q217 INDICATE WHICH ONE OF THE FOLLOWING APPLICATIONS OR DISADVANTAGE OF RADAR BEACONS IS FALSE
(a)target identification
(b)navigation
(c)very significant extension of the maximum range
(d)more accurate tracking of enemy targets
ans-d

Q218 COMPARED WITH OTHER TYPES OF RADAR ,PHASED ARRAY RADAR HAS THE FOLLOWING ADVANTAGES(INDICATE THE FALSE STATEMENT)
(a)very fast scanning
(b)ability to track and scan simultaneously
(c)critical simplicity
(d)ability to track many targets simultaneously.
ans-c

Q219 INTERLACING IS USED IN TELEVISION TO
(a)produce the illusion of motion
(b)ensure that all the lines on the screen are scanned ,not merely the alternate ones
(c)simplify the vertical sync pulse train
(d)avoid flicker
ans-d

Q220 THE SIGNALS SENT BY THE TV TRANSMITTER TO ENSURE CORRECT SCANNING IN THE RECEIVER ARE CALLED
(a)sync
(b)chroma
(c)luminance
(d)video
ans-a

Q221 INDICATE WHICH OF THE FOLLOWING VOLTAGES IS NOT FOUND IN THE O/P STAGE OF A NORMAL MONOCHROME RECEIVER VIDEO DETECTOR
(a)sync
(b)video
(c)sweep
(d)sound
ans-c

Q222 IN TELEVISION 4:3 REPRESENTS THE
(a)interlace ratio
(b)maximum horizontal defletion
(c)aspect ratio
(d)ratio of the two diagonals
ans-c

Q223 EQUALIZING PULSE IN TV ARE SENT DURING
(a)horizontal blanking
(b)vertical blanking
(c)the serrations
(d)the horizontal retrace
ans-b

Q224 THE FUNCTION OF THE SERRATIONS IN THE COMPOSITE VIDEO WAVEFORM IS TO
(a)equalize the charge in the integrator before the start of vertical retrace
(b)help vertical synchronisation
(c)help horizontal synchronisation
(d)simplify the generation of the vertical sync pulse
ans-c

Q225 INDICATE WHICH OF THE FOLLOWING FREQUENCIES WILL NOT BE PRESENT IN THE O/P OF A NORMAL TV RECEIVER
(a)4.5mhz
(b)41.25mhz
(c)45.75mhz
(d)42.17mhz
ans-a

Q226 THE VOLTAGE APPLIED TO THE PICTURE TUBE OF A TELEVISION RECEIVER IS FED IN
(a)b/w grid and ground
(b)to the yoke
(c)to the anode
(d)b/w grid and cathode
ans-d

Q227 THE CIRCUIT THAT SEPARATES SYNC PULSES FROM THE COMPOSITE VIDEO WAVEFORM IS
(a)the keyed agc amplifier
(b)a clipper
(c)an integrator
(d)a differentiator
ans-b

Q228 THE O/P OF THE VERTICAL AMPLIFIER APPLIED TO THE YOKE IN A TV RECEIVER ,CONSISTS OF
(a)direct current
(b)amplified vertical sync pulses
(c)a sawtooth voltage
(d)a sawtooth current
ans-d

Q229 THE HV ANODE SUPPLY FOR THE PICTURE OF A TUBE OF A RECEIVER IS GENERATED IN THE
(a)main transform
(b)vertical o/p stage
(c)horizontal o/p stage
(d)horizontal deflection oscillator
ans-c

Q230 ANOTHER NAME FOR THE HORIZONTAL RETRACE IN A RECEIVER IS THE
(a)ringing
(b)burst
(c)damper
(d)flyback
ans-d

Q231 THE SHADOW MASK IN A COLOUR PICTURE TUBE IS USED TO
(a)reduce x-ray emission
(b)ensure that each beam hits only one dots
(c)increase screen brightness
(d)provide degaussing for the screen
ans-b

Q232 IN A TV RECEIVER ,THE COLOUR KILLER
(a)cuts off the chroma stages during monochrome reception
(b)ensure that no colour is transmitted to monochrome receiver
(c)prevents colour overloading
(d)makes sure that the colour burst is not mistaken for sync pulses,by cutting off reception during the back poarch
ans-a
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any update???
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Any update ? Anyone received test/interview call ?
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Old Tuesday, July 18, 2017
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yesterday, PTA was conducted my interview at Islamabad. lets hope for best IA
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Hmmm Nice, best of luck. When you gave test ?
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Hi,

Can you kindly guide about the test conducted against post of assistant director technical and also share your interview experience
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