Railways NTPC (Technical Ability) Radio Communication and Radar Systems Question Bank

done Radio Communication and Radar Systems Total Questions - 50

• question_answer1)
  Virtual height of an ionosphere layer is........... the beat height
  A)
   less than                       done clear
  B)
   equal to done clear
  C)
   more than         done clear
  D)
   none of these done clear
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• question_answer2)
  In ground wave propagation the absorption of waves
  A)
   decreases with frequency done clear
  B)
   increases with frequency done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer3)
  The ionosphere consists of
  A)
   positively charged layer done clear
  B)
   negatively charged layer done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
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• question_answer4)
  In radio receiver's tube EM84 is used as
  A)
   audio amplifier  done clear
  B)
   magic eye done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
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• question_answer5)
  In a radio receiver the noise is generally increased by
  A)
   power supply                 done clear
  B)
   mixer done clear
  C)
   local oscillator   done clear
  D)
   none of these done clear
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• question_answer6)
  The value of a resistor creating thermal noise is doubled. The noise power generated will be
  A)
   halved              done clear
  B)
   doubled done clear
  C)
   unchanged                    done clear
  D)
   none of these done clear
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• question_answer7)
  Which of the following noise is of great importance at high frequencies?
  A)
   Flicker noise                  done clear
  B)
   Transit-time noise done clear
  C)
   Short noise                    done clear
  D)
   None of these done clear
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• question_answer8)
  Neper is
  A)
   equal to decibel done clear
  B)
   smaller than decibel done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
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• question_answer9)
  Which of the following crystal filter is used only at the higher frequencies?
  A)
   Half lattice                    done clear
  B)
   Ladder done clear
  C)
   Crystal gale                   done clear
  D)
   None of these done clear
  View Solution play_arrow

• question_answer10)
  The frequency at which the reactance of the two arms in a crystal gate are equal is
  A)
   zero done clear
  B)
   maximum attenuation frequency done clear
  C)
   both [a] and [b] done clear
  D)
   none of the above done clear
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• question_answer11)
  The effect of transit-time noise is significant in
  A)
   HP                               done clear
  B)
   LF done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer12)
  A beat frequency between 1500 kHz and 1955 kHz is
  A)
   455 kHz            done clear
  B)
   350 kHz done clear
  C)
   665 kHz                        done clear
  D)
   750 kHz done clear
  View Solution play_arrow

• question_answer13)
  In troposcatter which of the following antenna is preferred?
  A)
   Parabolic antenna          done clear
  B)
   Lens antenna done clear
  C)
   Both [a] and [b] done clear
  D)
   None of these done clear
  View Solution play_arrow

• question_answer14)
  In a radio receiver padders are provided
  A)
   to improve tracking        done clear
  B)
   to improve sensibility done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer15)
  Diversity reception system is used to minimize the troubles due to                                          
  A)
   synchronous fading                            done clear
  B)
   general fading only                             done clear
  C)
   both [a] and [b]                     done clear
  D)
   none of the above   done clear
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• question_answer16)
                          The output of a diode detector does not contain
  A)
   output signal                 done clear
  B)
   modulating signal     done clear
  C)
   both [a] and [b] done clear
  D)
   none of these       done clear
  View Solution play_arrow

• question_answer17)
    When power ratios are expressed in dB m, the reference power is                                            
  A)
   1 mW               done clear
  B)
   3 mW                done clear
  C)
   2 mW               done clear
  D)
   5 mW      done clear
  View Solution play_arrow

• question_answer18)
            Which stage contains the primary of the first IF transformer
  A)
   Oscillator                      done clear
  B)
   Detector              done clear
  C)
   Both [a] and [b] done clear
  D)
   None of these      done clear
  View Solution play_arrow

• question_answer19)
     During heterodyne process in a receiver the modulation of the signal the signal                                          
  A)
   increases                       done clear
  B)
   decreases           done clear
  C)
   remains constant            done clear
  D)
   both [a] and [b] done clear
  View Solution play_arrow

• question_answer20)
  Channel capacity is equal to                         
  A)
   parabolic antenna          done clear
  B)
   lens antenna         done clear
  C)
   both [a] and [b] done clear
  D)
   none of these     done clear
  View Solution play_arrow

• question_answer21)
       If the image frequency is 2010 kHz, the frequency must be                                        
  A)
   1350 kHz                      done clear
  B)
   1500 kHz           done clear
  C)
   1700 kHz                      done clear
  D)
   none of these       done clear
  View Solution play_arrow

• question_answer22)
  Three-point tracking is achieved by                 
  A)
   the padder capacitor       done clear
  B)
   variable selectivity   done clear
  C)
   both [a] and [b] done clear
  D)
   none of these   done clear
  View Solution play_arrow

• question_answer23)
         The input of the mixer stage is                     
  A)
   RF signals only                               done clear
  B)
   local oscillator signals only                       done clear
  C)
   signals only                                      done clear
  D)
   both [a] and [b]   done clear
  View Solution play_arrow

• question_answer24)
                The disadvantage of tuned radio frequency receiver is 
  A)
   band width variation      done clear
  B)
   in stability           done clear
  C)
   both [a] and [b] done clear
  D)
   none of these    done clear
  View Solution play_arrow

• question_answer25)
      Radar is                                            
  A)
   a mechanical device                          done clear
  B)
   an electrical device                                done clear
  C)
   a pneumatic device done clear
  D)
   an electromagnetic device done clear
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• question_answer26)
  The Chain Home Low System is effective within the rana of....... from the target,
  A)
   5 km                            done clear
  B)
   7 km done clear
  C)
   10 km              done clear
  D)
   15 km done clear
  View Solution play_arrow

• question_answer27)
  Radars can be used under
  A)
   bad weather conditions done clear
  B)
   good weather conditions done clear
  C)
   all weather conditions done clear
  D)
   none of these     done clear
  View Solution play_arrow

• question_answer28)
                              Chain Home System was designed for the location and detection of
  A)
   enemy done clear
  B)
   approaching aircraft bombers done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer29)
  Air-traffic control radar monitors are installed
  A)
   in vicinity of airports done clear
  B)
   enrooted between air terminals done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer30)
  In communication receivers the fidelity is provided by
  A)
   audio stage                   done clear
  B)
   mixer stage done clear
  C)
   both [a] and [b] done clear
  D)
   None of these done clear
  View Solution play_arrow

• question_answer31)
  Surveillance raders detect and locate hostile targets for the purpose of
  A)
   military action   done clear
  B)
   proper military action done clear
  C)
   war                  done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer32)
  Radars are used in
  A)
   detection                       done clear
  B)
   tracking of weather done clear
  C)
   both [a] and [c] done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer33)
  Radar can be used to guide
  A)
   vehicles            done clear
  B)
   space vehicles done clear
  C)
   the science                    done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer34)
  In Chain Home Low System, same aexial was used for
  A)
   transmission and modulation done clear
  B)
   reception and modulation done clear
  C)
   transmission and reception done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer35)
  The performance of radar is unaffected by
  A)
   darkness                       done clear
  B)
   fog done clear
  C)
   rain                              done clear
  D)
   [a], [b] and [c] done clear
  View Solution play_arrow

• question_answer36)
  Chain Home Low System was first introduced in
  A)
   1952                done clear
  B)
   1959 done clear
  C)
   1964                            done clear
  D)
   1972 done clear
  View Solution play_arrow

• question_answer37)
  In foul weather, radar is used with Ground Controlled Approach (GCA) System to guide aircrafts
  A)
   to a safe landing            done clear
  B)
   in any direction done clear
  C)
   to fly in the sky  done clear
  D)
   none of the above done clear
  View Solution play_arrow

• question_answer38)
  Distance Early Warning (DEW) radar/radars is/are used to detect the
  A)
   aircrafts            done clear
  B)
   enemies done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer39)
  The techniques developed for radar have paved the way of more advanced research in
  A)
   solar system                  done clear
  B)
   microwave done clear
  C)
   spectroscopy                 done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer40)
  Radar has vastly increased out knowledge of meteorology, aurora, meteors, and other objects of the
  A)
   sciences                        done clear
  B)
   world done clear
  C)
   solar system done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer41)
  In Chain Home Low System, the target ranges were more than
  A)
   100 km done clear
  B)
   85 km done clear
  C)
   65 km              done clear
  D)
   75 km done clear
  View Solution play_arrow

• question_answer42)
  When installed in ships or high flying aero planes, radars can be used under all weather conditions to find the positions of mountains and
  A)
   icebergs in the sea          done clear
  B)
   shore lines done clear
  C)
   lakes etc.                      done clear
  D)
   [a], [b] and [c] done clear
  View Solution play_arrow

• question_answer43)
  Hartley law states that
  A)
   the maximum rate of information transmission depends on the depth of modulation done clear
  B)
   me maximum rate of information transmission depends on the channel bandwidth. done clear
  C)
   redundancy is essential done clear
  D)
   only binary codes may be used. done clear
  View Solution play_arrow

• question_answer44)
  The Ballistic Missile Early Warning Systems radar is used to detect the track of
  A)
   missiles done clear
  B)
   ballistic missiles done clear
  C)
   intercontinental ballistic missiles done clear
  D)
   both [a] and [b] done clear
  View Solution play_arrow

• question_answer45)
  Radar is used by military for
  A)
   surveillance done clear
  B)
   safety done clear
  C)
   weapons                       done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer46)
  Radar can be used for the exploration of
  A)
   solar system                  done clear
  B)
   interplanetary space done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer47)
  Radar is used by ships, large and small, for navigation especially in
  A)
   bad weather                  done clear
  B)
   with poor visibility done clear
  C)
   [a] and [b]                    done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer48)
  Chief civilian application of radar has been for....... navigation.
  A)
   marine              done clear
  B)
   air done clear
  C)
   both [a] and [b] done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer49)
  Radar can be used in
  A)
   satellites                        done clear
  B)
   space research done clear
  C)
   solar system                  done clear
  D)
   none of these done clear
  View Solution play_arrow

• question_answer50)
  Radar gives target's:
  A)
   Range               done clear
  B)
   Size done clear
  C)
   Velocity and range         done clear
  D)
   Color done clear
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