Communication Systems - ECE Questions and Answers

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Probability of error in DPSK is less than PSK

true

false

equal

depend upon noise

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Two sine waves of amplitude A₁ and A₂ are multiplied. The amplitude of the spectral component is

A₁A₂

(A₁A₂)^1/2

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In radar display system PPI stands for

Pulse Position Indicator

Plan Position Indicator

Phase Position Indicator

Point Position Indicator

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In phase shift keying the input signal is

s_t(t) = A cos ω₀t and s₂(t) = - A cos ω₀t

s₁(t) = s₂(t) = A cos ω₀t

s₁(t) = A cos ω₀t and s₂(t) = A cos (ω₀t + p/2)

s₁(t) = A cos ω₀t and s₂(t) = - A (cos ω₀t + p/2)

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In figure the output v(t) is

an amplitude modulated signal

a frequency modulated signal

a phase modulated signal

none of the above

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If P_k be the probability of the message to be received or transmitted, then the amount of information (I_k) associated, in bits, will be

I_k = log₂ P_k

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A circuit which cannot demodulate SSB is

balanced modulator

product detector

BFO

phase discriminator

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In TV system in India IF video and IF audio frequencies are

33.4 and 28.4 MHz respectively

38.9 and 33.4 MHz respectively

43.8 and 38.9 MHz respectively

33.4 and 38.9 MHz respectively

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Assertion (A): The unit of telephone traffic measurement is erlang.

Reason (R): International circuits for communication are fitted with echo suppressors.

Both A and R are correct and R is correct explanation of A

Both A and R are correct but R is not correct explanation of A

A is correct but R is wrong

A is wrong but R is correct