76.

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A 1 MHz sinusoidal carrier is amplitude modulated by a symmetrical square wave of
period 100 psec. Which of the following frequencies will not be present in the modulated
signal ?
(A) 990 kHz ൫ 1010 kHz
(C) 1020 kHz (D) 1030 kHz

A super-heterodyne radio receiver with an intermediate frequency of 455 kHz is tuned to
a station operating at 2800 kHz. The associated image frequency is

(A) 3710 kHz (B) 3255 kHz
(C) 2345 kHz (D) 1890 kHz

In a BPSK signal detector, the local oscillator has a fixed phase error of 40°. This phase
error deteriorates the SNR at the output by a factor of

(A) ००5 40° (8) cos? 40°
(C) cos 80° (2) 0082 80°

Compression in PCM refers to relative compression of
(A) _ lower signal frequencies (8) _ lower signal amplitudes
(C) higher signal amplitudes (D) higher signal frequencies

The Fraunhofer field of an antenna varies with distance ‘r’ as
(A) 17 (B) 1
(€) 1/3 D) 1.

A transmission line is feeding 2 Watt of power to a horn antenna having a gain of 10 dB.
The antenna is matched to the transmission line. The total power radiated by the horn
antenna into the free — space is

(A) 10 Watts (8) 1 Watt

(C) 5 Watts (D) 20 Watts

The design of optimum equi ripple linear phase FIR filter uses
(A) Butterworth approximation (B) Chebyshev approximation
(C) Hamming approximation (D) None of the above

Which mode of propagation is adopted in HF antennas ?
(A) 1000801010 (B) Ground wave

(6) Tropospheric (D) Sky wave

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