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UGC NET Paper 2: Electronic Science June 2019 Official Paper

Option 2 : 0.5 mS

CT 1: Current Affairs (Government Policies and Schemes)

54676

10 Questions
10 Marks
10 Mins

Given:

R_{b} = 4 kbps

In FSK, the best possible interval between the carriers is given as:

\(ΔT = \frac{2}{R_b}\)

\(ΔT = \frac{2}{4 \ kbps}\)

ΔT = 0.5 msec

__FSK (Frequency Shift Keying)__:

In FSK (Frequency Shift Keying) binary 1 is represented with a high-frequency carrier signal and binary 0 is represented with a low-frequency carrier, i.e. In FSK, the carrier frequency is switched between 2 extremes.

For binary ‘1’ → S1 (A) = Acos 2π fHt

For binary ‘0’ → S2 (t) = A cos 2π fLt . The constellation diagram is as shown:

__ASK(Amplitude Shift Keying)__:

In ASK (Amplitude shift keying) binary ‘1’ is represented with the presence of a carrier and binary ‘0’ is represented with the absence of a carrier:

For binary ‘1’ → S1 (t) = Acos 2π fct

For binary ‘0’ → S2 (t) = 0

The Constellation Diagram Representation is as shown:

where ‘I’ is the in-phase Component and ‘Q’ is the Quadrature phase.

__PSK(Phase Shift Keying)__:

In PSK (phase shift keying) binary 1 is represented with a carrier signal and binary O is represented with 180° phase shift of a carrier

For binary ‘1’ → S1 (A) = Acos 2π fct

For binary ‘0’ → S2 (t) = A cos (2πfct + 180°) = - A cos 2π fct

The Constellation Diagram Representation is as shown: