MCQ SOLUTIONS AVIONICS 1-AERONAUTICAL SOCIETY OF INDIA

FOLLOWING ARE THE MCQ QUESTIONS THAT ASKED IN AVIONICS 1 PAPER OF AERONAUTICAL SOCIETY OF INDIA EXAM.ANSWERS FOR THESE QUESTIONS ARE GIVEN AT THE END OF EACH QUESTION.IN AVIONICS 1 MCQ TYPE QUESTIONS ARE ASKED FROM JUNE 2015,SO I HAVE ANSWERED THREE QUESTION PAPERS(UP TO DATE)  THAT INCLUDE SESSIONS JUNE 2015,DECEMBER 2015 AND JUNE 2016.
ALSO THESE QUESTIONS CAN ASKED IN PSU EXAMS AND IN OTHER ENGINEERING UNIVERSITY EXAMS WHICH COVER THE TOPICS MODULATION,RADIO COMMUNICATION,TELEVISION ENGINEERING,TRANSMISSION LINES ETC.


1.The following stage in a super hetrodyne receiver provides the maximum image signal selectivity:
(a) RF amplifier   (b) IF amplifier  (c) AF amplifier (d) Mixer
Answer: RF amplifier

2.A sinusoidal voltage amplitude modulates another sinusoidal voltage of amplitude 1 KV resulting in two side bands each of magnitude 200 V.The modulation index mf is
(a)0.1    (b) 0.2  (c) 0.4   (d) 0.5
Answer:0.4

3.FM discriminator changes FM signal in to
(a) AM signal   (b) FM signal   (c) PM signal  (d) Audio signal
Answer:audio signal

4.In an AM SYSTEM,antenna current(rms) before modulation is 5 A  and it  increases to 5.8 A after modulation.The percentage of modulation index will be
(a) 88%   (b) 80%  (c) 83.14%  (d) 81.21%

Answer:83.14%

5.The following circuit cannot demodulate AM DSB/SC signal
(a) balanced modulator    (b) BFO  (c) phase discriminator  (d) product detector

answer:phase discriminator

6.In a TV system, the function of equalizing pulses is
(a) To smooth out difference between the vertical sync signals
(b) to maintain horizontal synchronization
(c) to smooth out difference between the horizontal,sync signals
(d) to reduce the bandwidth of transmission

Answer:To smooth out difference between vertical sync signals

7.The modulation index of an AM DSB/FC signal is changed from 0 to 1.The total transmitted power is:
(a) un changed    (b) halved   (c) doubled    (d) increased by 50%

Answer:increased by 50%

8.In an SSB transmitter,one is most likely to find a
(a) Class C audio amplifier    
(b) tuned modulator  
(c) Class B RF amplifier
(d) Class A RF output amplifier
Answer:Class A RF output amplifier

9.An FM signal with deviation & is passed through a mixer and has its frequency reduced five fold.The deviation at the input of thee mixer is
(a) 5&   (b) indeterminate    (c) 0.2&   (d) &
Answer:&
note:& is not the correct symbol

10.An FM signal with a modulation index Mf  is passed through a frequency tripler. The wave at the output of the tripler will have a modulation index of

(a)  (1/3)Mf   (b) Mf   (c)3Mf   (d) 9Mf
Answer:3Mf

11.A (75-j50)  load is connected to a transmission line of characteristic impedance of Z0= 75 ohm at 11 GHz. The best method of matching consists in connecting
(a) a short circuited stub at the load
(b) an inductance at the load
(c) a capacitance at some specific distance from the load
(d) a short circuited stub at some specific distance from the load

Answer: a short circuited stub at some specific distance from the load

12. In a broadcast superhetrodyne radio receiver,the
(a) local oscillator operates below the signal frequency
(b) mixer output must be tuned to the signal frequency
(c) local oscillator frequency is normally double of the IF
(d) RF amplifier normally works at 455 KHz above the signal frequency

Answer:mixer output must be tuned to the signal frequency

13.To permit the selection of 1 out of 16 equi probable events,the number of bits required is:
(a) 2      (b) log10 16  (c) 8  (d) 4
ANSWER:4

14. The biggest  disadvantage of pcm system is 
(a) its inability to handle analog signals
(b) the high error rate which its quantization noise introduces
(c) its incompability with TDM
(d) the large bandwidth required for its transmission

ANSWER:THE LARGE BANDWIDTH REQUIRED FOR ITS TRANSMISSION

15.To separate channels in an FDM receiver,it is necessary to use
(a) AND gates   (b) BPF   (c) differentiation  (d) integration

ANSWER: BPF

16.  To separate channels in an TDM receiver,it is necessary to use

(a) AND gates   (b) BPF   (c) differentiation  (d) integration
Answer: AND gates

17. Equalizing pulses in a TV system are sent during
(a) Horizontal blanking   (b) vertical blanking
(c) the serrations             (d) the horizontal retrace
Answer: vertical blanking

18.Vestigial side band transmissions normally used for
(a) HF point to point communications
(b) FM broadcasting
(c) TV broadcasting
(d) Stereo broadcasting
Answer: TV broadcasting

19.A SUPER hetrodyne receiver with an IF  OF 450 KHz  is tuned to a signal at 1200 KHz.The image signal frequency is:
(a) 750 KHz   (b) 900 KHz  (c) 1650 KHz     (d) 2100 KHz
answer:2100 KHz

20.Pulse width modulation may be generated
(a) by differentiating pulse position modulation
(b) using  monostablemultivibrator(MMV)
(C) by integrating the pulse position modulated signal
(d) using a free running muyltivibrator(AMV)
Answer: using a monostablemultivibrator
(mmv)

21.In order to reduce quantization noise in PCM system one must
(a) increase the number of standard amplitudes
(b) send pulses whose sides are more nearly vertical
(c) use an RF amplifier at the receiver end
(d) increase the number of samples per second
Answer:Increase the number of standard amplitudes

22.Time division multiplexing (TDM)
(a) can be used with PCM ONLY
(b) combines five groups in to a super group
(c) stacks 24 channels in adjacent frequency slots
(d)interleaves pulses belonging to different transmissions
Answer: interleaves pulses belonging to different transmissions 

23. The video voltage applied to the picture tube of a TV receiver is fed in
(a) between grid and ground          (b) to the yoke

(c) between grid and cathode  (d) to the anode

ANSWER:between grid and cathode

24.the number of lines in Indian TV system is
(a) 312.5     (b) 625
(c) 50           (d) 15625

Answer:312.5