Introduction
Analog communication
pulse modulation
Digital communication
Applications
100
motor
which of the following is not a part of communication
antenna
transmitter
motor
100
duplex arrangement
A cordless telephone using separate frequencies for transmission in base and portable units is known as
100
When data rate in bits per second is upto 600, modem is low speed.
A modem is classified as low speed if data rate handled is
100
VSB (vestigial side band) transmission transmits one side band fully and the other side band partially thus, reducing the bandwidth requirement.
VSB modulation is preferred in TV because
100
Woofer is a low frequency loud speaker covering the range 16 Hz to 500 Hz.
A woofer should be fed from the input through a
200
In frequency interleaving the space between bundles is used for colour signal.
The colour subcarrier and sidebands produced by its modulation with the chrominance signals are accommodated in the standard channel width by the process of
200
Frequency multiplier increase the deviation,
In FM signal with a modulation index mf is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of
200
In varactor diode the applied reverse bias controls the width and therefore capacitance of depletion layer.
This capacitance is used for tuning.
In colour TV receiver, varactor diode is used for
200
Shot noise, partition noise and thermal noise.
The number of noise sources in a BJT are
200
Atmospheric noise decreases as frequency is increased.
Energy content of atmospheric noise
300
512 W
A 400 W carrier is amplitude modulated with m = 0.75. The total power in AM is
300
PSK
Non-coherently detection is not possible for
300
fully steerable antenna
Tracking of extra terrestrial objects requires
300
PRF in radar systems means pulse repetition frequency.
In radar systems PRF stands for
300
x(t) = cos t + 0.5
Which of the following cannot be the Fourier series expansion of a periodic signal?
400
It generates FM through phase modulation.
Which of the following is the indirect way of FM generation?
400
Calling rate is the number of calls per subscriber.
A telephone exchange has 9000 subscribers. If the number of calls originating at peak time is 10, 000 in one hour, the calling rate is
400
Because of this reason ground waves can be used for frequencies upto about 1600 kHz only.
As the frequency increases, the absorption of ground wave by earth's surface
400
v ∝ T.
The velocity of sound waves in air
400
The range depends on quality of instrument and is about 100 m.
The range of a cordless telephone is about
500
The number of radials is large and depth is about 30 cm.
An earth mat for a communication tower consists of
500
Since gauss is a unit of magnetic flux, degaussing means removal of magnetism.
Degaussing in a picture tube means
500
Rate of information depends on bandwidth.
The rate at which information can be carried through a communication channel depends on
500
absorption traps
Some types of traps used in video IF amplifier of colour TV are
500
m1 = 0.4, m2 = 0.3
.
A carrier is simultaneously modulated by two sine waves having modulation indices of 0.4 and 0.3. The total modulation index will be