Communications [GATE (Graduate Aptitude Test in Engineering) Electronics]: Questions 63 - 66 of 106

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Question 63

Communications
SNR and BER for Digital Modulation

Appeared in Year: 2014 (UGC-NET)

Question

Assertion-Reason▾

Assertion(Ꭺ)

The most commonly used amplifier in S/H circuit is unity gain NINV amplifier. (December)

Reason(Ꭱ)

At the sampling state signal building is not desired.

Choices

Choice (4)Response

a.

Both Ꭺ and Ꭱ are false

b.

Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ

c.

Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ

d.

Ꭺ is false but Ꭱ is true

Question 64

Communications
Amplitude Modulation and Demodulation

Appeared in Year: 2014 (UGC-NET)

Question

MCQ▾

In FM (December)

Choices

Choice (4)Response

a.

Carrier never becomes zero

b.

Total power remains constant with respect to modulation index

c.

Pulse rate decreases

d.

J-coefficient occasionally are negative

Passage

Optical fibre communication is one among the new techniques have come up and are extensively used for communication purposes. The portion of the e. m. spectrum encompasses the optical region falls in the wavelength of 50 nm (Ultraviolet) to approximately 100 µm (Infrared) which includes visible light spectrum from 400 nm (Violet) to 700 nm (Red) . The order of frequency corresponding to these wavelengths falls in the range to Hz. There are two types of transmission media used for optical communication i.e.. , atmospheric channel and guided wave channel. Out of the two, guided wave channel provide much more reliable and versatile medium of communication. The medium used for guided channels in optical range are non-metallic guides popularly known as optical fibre. The optical fibre link used for communication applications has several advantages over conventional cupper cable links which makes possible to send much more data over long distances with negligible attenuation. Although some difficulties do exist in the making of optical fibre set and there are some challenges being faced yet this type of communication mechanism has made a great impact in the present scenario.

Question 65 (1 of 1 Based on Passage)

Communications
Circuits for Analog Communications

Appeared in Year: 2014 (UGC-NET)

Question

MCQ▾

Following is not the usual classification of an optical fibre: (December)

Choices

Choice (4)Response

a.

Multimode step index

b.

Single mode step index

c.

Multimode graded index

d.

Single mode graded index

Question 66

Communications
Amplitude Modulation and Demodulation

Appeared in Year: 2014 (UGC-NET)

Question

Match List-Ⅰ List-Ⅱ▾

Match the following lists: (December)

List-Ⅰ (Column-I)List-Ⅱ (Column-II)
(A)

DSB-SC modulation

(i)

Weaver՚s method

(B)

SSB-modulation

(ii)

Envelope detection

(C)

Phase-shift detection

(iii)

Balanced modulator

(D)

AM-demodulation

(iv)

Foster Seeley

Choices

Choice (4)Response
  • (A)
  • (B)
  • (C)
  • (D)

a.

  • (iii)
  • (ii)
  • (iv)
  • (i)

b.

  • (i)
  • (ii)
  • (iv)
  • (iii)

c.

  • (iii)
  • (i)
  • (iv)
  • (ii)

d.

  • (ii)
  • (iv)
  • (i)
  • (iii)

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