Technical Ability - SPLessons
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Communication System

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SPLessons 5 Steps, 3 Clicks
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Communication System

shape Introduction

"Communication is the act of conveying intended meanings from one entity or group to another through the use of mutually understood signs and semiotic rules." Communication System describes communication exchanges between two stations, transmitter and receiver or between source and destination. Signals or information pass from source to destination through what is called channel. Communication system is a system that describes communication with various hardware and software tools. There is a information source, transmitter, channel, receiver, destination in a communication system. "In telecommunication, a communications system or communication system is a collection of individual communications networks, transmission systems, relay stations, tributary stations, and data terminal equipment (DTE) usually capable of interconnection and interoperation to form an integrated whole".

shape Quiz

Q1. The black and white or monochrome portion of the total colour signal is equivalent in all respects to present signals.
    A. black and white B. red and blue C. yellow and green D. red and yellow Answer: A

Q2. The illumination on screen when there is no broadcast or telecast, is known as
    A. raster B. contrast C. both (a) and (b) D. none of the above Answer: A

Q3. The demodulation of sound signals in a TV receiver is accomplished by
    A. envelope detector B. discriminator C. both (a) and (b) D. none of the above Answer: B

Q4. In TV receivers, the electron beam is deflected by
    A. electromagnetic technique B. electrostatic technique C. both (a) and (b) D. none of the above Answer: B

Q5. A primary colour differs from its complementary by a phase angle of
    A. 180° B. 3 C. 4 D. 6 Answer: A

Q6. The linearity of a TV receiver can be checked by
    A. multiplier B. vector gram C. both (a) and (b) D. none of the above Answer: B

Q7. Equalizing pulses in TV are sent during
    A. vertical blanking B. horizontal blanking C. both (a) and (b) D. none of the above Answer: A

Q8. A total colour signal consists of
    A. one component B. two components C. five components D. three components Answer: B

Q9. A live programme is transmitted from location to TV station through
    A. cables B. wireless C. antennas D. none of the above Answer: A

Q10. Colour TV camera is essentially a combination of ..... basic cameras.
    A. five B. two C. four D. three Answer: D
Q11. For 51 cm size TV the voltage required for picture tube is the order of
    A. 13 kV B. 15 kV C. 17 kV D. 25 kV Answer: B

Q12. Which of the following signals is not transmitted in colour TV?
    A. Q B. I C. R D. none of the above Answer: C

Q13. Which channel has the highest frequency range?
    A. Channel 7 B. Channel 5 C. All channels have same frequency range D. None of the above Answer: C

Q14. The signal sent by the TV transmitter to ensure correct scanning in the receiver are called
    A. chrome B. syn c C. video D. none of these Answer: B

Q15. The light is converted into video signals corresponding to the red, blue and green components of the ............. picture.
    A. white B. black C. red D. original colour Answer: D

Q16. Which of the following conducts during flyback?
    A. Silicon diode damper B. Output stage C. High voltage rectifier D. None fo the above Answer: C

Q17. The output of the vertical amplifier applied to the yoke in a TV receiver, consists of
    A. a saw tooth voltage B. a saw tooth current C. both (a) and (b) D. none of the above Answer: B

Q18. The method of modulation of sound in TV system in India is
    A. amplitude modulation B. frequency modulation C. both (a) and (b) D. none of the above Answer: B

Q19. Which of the following are secondary colours?
    A. All colours other than green, blue and red B. Green, blue and red C. White and black D. None of the above Answer: A

Q20. In TV if three is no brightness but sound is normal, the trouble could be in
    A. horizontal oscillator B. vertical oscillator C. both (a) and (b) D. none of the above Answer: A
Q21. A number of different colours can be formed by the combinations of colours in
    A. two colours B. three colours C. five colour D. seven colours Answer: B

Q22. The fine tuning control in television receiver is
    A. a potentiometer B. a variable capacitor C. both (a) and (b) D. anyone of the above Answer: A

Q23. In T. V. system
    A. picture and sound are frequency modulated B. picture and sound are amplitude modulated C. picture is amplitude modulated while sound is frequency modulated D. none of the above Answer: C

Q24. TV br oadcastin g system in In dia is as per CCIR
    A. system X B. system B C. system A D. system I Answer: B

Q25. The sound signal in video composite signal of TV is
    A. FSK B. AM C. FM D. none of the above Answer: C

Q26. The three primary colours are
    A. red, orange and blue B. red, blue and green C. red, yellow and blue D. none of the above Answer: A

Q27. The number of frames per second in TV system in India is
    A. 25 B. 80 C. 20 D. 75 Answer: A

Q28. Which of the following will increase the antenna radiation efficiency?
    A. Providing insulation on conductor B. Top loading of antenna C. Both (a) and (b) D. None of the above Answer: B

Q29. Which of the following is non-resonant antenna?
    A. The folded dipole B. The end-fire array C. The broad side array D. Both (b) and (c) Answer: B

Q30. Scatter transmission is used at frequencies
    A. Very low frequency (VLF) B. Ultra high frequency (UHF) C. Very high frequency (VHF) only D. Both (b) and (c) Answer: D
Q31. A helical antenna is used for satellite tracking because of its
    A. manoeuvrability B. broadwidth C. good FBR D. none of the above Answer: A

Q32. Which type of fading causes serious distortion of modulated signal?
    A. Polarisation fading B. fading C. Selective fading D. Both (a) and (b) Answer: C

Q33. Which of the following antenna gives circular polarisation?
    A. Helical B. Dipole C. Both (a) and (b) D. None of these Answer: A

Q34. Which antenna does not depend on frequency?
    A. Log periodic antenna B. Yagi antenna C. Both (a) and (b) D. None of the above Answer: A

Q35. The frequency range for satellite communication is
    A. 3000 to 30,000 MHz B. 2000 to 25,000 MHz C. 45,000 to 65,000 MHz D. 75,000 to 1,25,000 MHz Answer: A

Q36. The gain of a current element is
    A. 1.76 dB B. 2.52 dB C. 3.58 dB D. 7.25 dB Answer: A

Q37. The power gain of a half-wave dipole with respect to an isotropic radiator is
    A. 6 dB B. 2.15 dB C. 7.25 dB D. 10.12 dB Answer: B

Q38. In order to receive a vertically polarized wave, the conductor of the dipole should be mounted
    A. at an an gle of 60° B. horizontally C. vertically D. at an angle of 45° Answer: C

Q39. A loop antenna is commonly used for
    A. direction finding B. satellite communication C. radar D. both (b) and (c) Answer: A

Q40. Which of the following is multi band high frequency receiving antenna?
    A. The folded dipole antenna B. Log-periodic antenna C. Square loop antenna D. None of the above Answer: B
Q41. The gain factor of a half dipole is
    A. 1.641 B. 1.252 C. 3.25 D. 7.95 Answer: A

Q42. The most important ionizing agents are
    A. ultra violet and a, b, l radiations from the Sun as well as cosmic rays and meteors B. infrared radiation being emitted by ground reactions occurring near the surface of earth C. radiations and emissions by the polluting industries on the earth D. none of the above Answer: A

Q43. Broadcasting antennas are generally
    A. vertical type B. horizontal type C. both (a) and (b) D. none of the above Answer: A

Q44. The night effect is most prominent in
    A. vertical antenna B. adcock antenna C. loop antenna D. (a) and (b) Answer: C

Q45. D-layer of ionosphere extends approxi-mately from
    A. 95 to 150 km B. 50 to 90 km C. 110 to 250 km D. 135 to 270 km Answer: B

Q46. An antenna is
    A. capacity coupled B. inductive C. both (a) and (b) D. none of these Answer: B

Q47. For aeroplane and navigation preferred frequency band is
    A. Very high frequency band B. Very low frequency band C. Ultra high frequency band D. none of the above Answer: C

Q48. Anomalous propagation is due to
    A. troposcatter B. super refractive duct C. meteorological factors D. none of the above Answer: C

Q49. If frequency of modulated wave is less than frequency of carrier wave, then input signal is
    A. Negative B. Positive C. Zero D. Infinite Answer: A

Q50. Decrease in strength of signal is known as:
    A. tuning B. modulation C. attenuation D. amplification Answer: C
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