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Question Bank No: 1

1. The Indian remote sensing satellites is

a)		Aryabhatt
b)		INSAT 2B
c)		Sputnik-1
d)		IR SIB

2. In space communication, the information can be passed from one place to another at a distance of 100km in

a)		1sec
b)		0.5 sec
c)		0.003sec
d)		none of these

3. As compared to AM transmiters, FM transmitters are

a)		less efficient
b)		more efficient
c)		equally efficient
d)		less costly

4. Oscillator crystal is made of

a)		silicon
b)		quartz
c)		germanium
d)		diamond

5. Basically a communication system is

a)		transmitter
b)		receiver
c)		messenger
d)		none of these

6. The cladding which surrounds the fibre core

a)		is used to reduce interference
b)		is used to reduce diffraction
c)		is used to protect the fibre
d)		helps to guide the light signals through the core

7. A signal fibre can handle as many voice channels as

a)		a pair of copper wire
b)		a 1500 pair of cable
c)		a 500 pair of cable
d)		a 10000 pair of cable

8. The date transmission rate of a modem is measured in

a)		byte per second
b)		bits per second
c)		megahertz
d)		Hz

9. Indicate which of the following systems is digital

a)		pulse- position modulation
b)		pulse - code modulation
c)		pulse- width modulation
d)		pulse- frequency modulation

10. Which of the following statement are true? Digital signals
(i) do not provide a continuous set of values
(ii) represent values as discrete step
(iii) can utilize only binary system and
(iv) can utilize decimal as well as binary system

a)		only (i) and (ii)
b)		only (i), (ii), and (iv)
c)		only (ii) and (iii)
d)		only (i) (ii) and (iii); but not (iv)

11. A carrier wave of 2000 kHz is amplitude modulated by 2kHz. The bandwidth required for the modulation is

a)		2 kHz
b)		2000 kHz
c)		20 kHz
d)		4kHz

12. A 550kHz carrier is amplitude modulated with 10kHz audio sine wave. The side band frequencies are (in kHz),

a)		560, 540
b)		550, 10
c)		560, 550
d)		550, 540

13. A TV tower has a height 100m. By how much the height of the tower has to be increased to triple its coverage range

a)		300 m
b)		800 m
c)		600 m
d)		500 m

14. If $n_{1}$ is the refractive index of the core and $n_{2}$ that of the cladding of an optical fibre, then

a)		$n_{1} > n_{2}$
b)		$n_{2} > n_{1}$
c)		$n_{1} = n_{2}$
d)		$n_{1} ≫ n_{2}$

15. The propagation of radio waves as ground waves is possiblr for wavelength

a)		less than 100 m
b)		less than 150m
c)		less than 175 m
d)		greater than 200

16. If the radius of the earth is R, the covering range of a TV transmitting tower of height h will be

a)		$\sqrt{R h}$
b)		$\sqrt{2 R h}$
c)		$\sqrt{2 R / h}$
d)		$\sqrt{h / 2 R}$

17. Frequencies in the UHF range normally propagate by means of

a)		ground waves
b)		sky waves
c)		surface waves
d)		space waves

18. Indicate which one of the following is not an advantage of FM over AM

a)		better noise immunity is provided
b)		lower bandwith required
c)		the transmitted power is more useful
d)		less transmitting distance

19. The difference between the phase modulation and frequency modulation

a)		is purely theoretical because they are the same in practice
b)		is too great to make the two systems compatible
c)		lies in the poorer response of phase modulation
d)		lies in the faithful transmission and reception

20. AM is used for broadcasting because

a)		it is more noise immune than other modulated systems
b)		it requires less transmitting power
c)		its use avoids receiver complexity
d)		no other modulating system can provide the necessary bandwith for high fidelity

21. Modulation is used to

a)		separate the transmission of different users
b)		reduce the bandwith used
c)		ensure that intelligence may be transmitted to long distances
d)		allow the use of practical antenna

22. The sound waves after being converted into electrical waves cannot be transmitted as such because

a)		they travel only with the speed of sound
b)		they are heavily absorbed by the atmosphere
c)		of the abnormal height of the antenna for transmission
d)		their frequency is not a constant

23. The process of superimpossing AF or VF wave with a high frequency carrier is called

a)		Interference
b)		Diffraction
c)		Modulation
d)		Lasing

24. At which of the following frequencies the communication will not be reliable for a receiver situated beyond the horizon

a)		100GHz
b)		100kHz
c)		150kHz
d)		1MHz

25. The wave used for telecommunication is

a)		ultraviolet
b)		X-ray
c)		Infrared
d)		Microwave