Test: Communication Systems - 1 - Electronics and Communication Engineering (ECE) MCQ

Separate frequencies for transmission from base and portable units allows two way transmission and is called duplex arrangement.

Since X_c for high frequencies is low, the high frequencies are shunted to ground and are not transmitted.

When data rate in bits per second is upto 600, modem is low speed.

VSB (vestigial side band) transmission transmits one side band fully and the other side band partially thus, reducing the bandwidth requirement.

Woofer is a low frequency loud speaker covering the range 16 Hz to 500 Hz.

In frequency interleaving the space between bundles is used for colour signal.

Frequency multiplier increase the deviation,

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In varactor diode the applied reverse bias controls the width and therefore capacitance of depletion layer.

This capacitance is used for tuning.

Shot noise, partition noise and thermal noise.

Atmospheric noise decreases as frequency is increased.

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As, we known FM, s(t)

Frequency deviation = 3 . (AM Bandwidth) = 6 f_m

and β= 6 is given in (d) only.

ω_c + n ω_m = (1008 x 10³)2p

2p x 10⁶ + n. 4p x 10³ = (1008 x 10³).2p

n = 4

So, β = 6, n = 4 hence answer is 5j₄(6).

All the three are required.

Since free space does not have magnetic and other fields, waves can propagate without any interference.

PRF in radar systems means pulse repetition frequency.

x(t) = cos t + 0.5

not satisfies the Dirichlet condition.

The integration of constant term is ∞.

It generates FM through phase modulation.

Calling rate is the number of calls per subscriber.

This is Shannon-Hartley theorem.

Because of this reason ground waves can be used for frequencies upto about 1600 kHz only.

v ∝ T.

The range depends on quality of instrument and is about 100 m.

The number of radials is large and depth is about 30 cm.

Since gauss is a unit of magnetic flux, degaussing means removal of magnetism.