Sunday, 28 September 2014


1. Indicate which one of the following system is digital

2. Basically, the product modulator is

3. The maximum distance upto which TV transmission from a TV tower of height h can be received is proportional to . [AIIMS 2003]

4. Advantage of optical fibre . [DCE 2005]

5. Laser beams are used to measure long distances because . [DCE 2002, 03]
6. Range of frequencies allotted for commercial FM radio broadcast is . [MNR 1997]

7. The phenomenon by which light travels in an optical fibres is . [DCE 2001]

8. Consider telecommunication through optical fibres. Which of the following statements is not true . [AIEEE 2003]

9. In which of the following remote sensing technique is not used . [Kerala PMT 2005]

10. What is the modulation index of an over modulated wave

11. An antenna is a device

12. Which of the following is the disadvantage of FM over AM

13. For sky wave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere .[AIIMS 2005]

14. The process of superimposing signal frequency (i.e. audio wave) on the carrier wave is known as . [AIIMS 1987]

15. In an amplitude modulated wave for audio frequency of 500 cycle/second, the appropriate carrier frequency will be . [AMU 1996]
16. In short wave communication waves of which of the following frequencies will be reflected back by the ionospheric layer, having electron density 1011 per m3 . [AIIMS 2003]

17. For television broadcasting, the frequency employed is normally . [AMU 2002]

18. Through which mode of propagation, the radio waves can be sent from one place to another . [JIPMER 2003]

19. A laser beam is used for carrying out surgery because it . [AIIMS 2003]

20. The waves used in telecommunication are
21. Audio signal cannot be transmitted because . [Kerala PMT 2005]

22. A step index fibre has a relative refractive index of 0.88%. What is the critical angle at the corecladding interface . [Manipal 2003]

23. Television signals on earth cannot be received at distances greater than 100 km from the transmission station. The reason behind this is that . [DCE 1995]

24. In frequency modulation . [Kerala PMT 2005]

25. In an FM system a 7 kHz signal modulates 108 MHz carrier so that frequency deviation is 50 kHz. The carrier swing is