Communication Systems

The maximum amplitude for an amplitude modulated wave is found to be 12V while the minimum amplitude is found to be 3V. The modulation index is 0.6x where x is ____________.

A transmitting antenna has a height of 320 m and that of receiving antenna is 2000 m. The maximum distance between them for satisfactory communication in line of sight mode is 'd'. The value of 'd' is ................. km.

An antenna is mounted on a 400 m tall building. What will be the wavelength of signal that can be radiated effectively by the transmission tower upto a range of 44 km?

The maximum and minimum amplitude of an amplitude modulated wave is 16V and 8V respectively. The modulation index for this amplitude modulated wave is x \(\times\) 10\(-\)2. The value of x is __________.

If the highest frequency modulating a carrier is 5 kHz, then the number of AM broadcast stations accommodated in a 90 kHz bandwidth are _________.

An amplitude modulated wave is represented by Cm(t) = 10(1 + 0.2 cos 12560t) sin(111 \(\times\) 104t) volts. The modulating frequency in kHz will be ................. .

A transmitting antenna at top of a tower has a height of 50 m and the height of receiving antenna is 80 m. What is range of communication for Line of Sight (LoS) mode?[use radius of earth = 6400 km]

In amplitude modulation, the message signalVm(t) = 10 sin (2\(\pi\) \(\times\) 105t) volts and Carrier signalVC(t) = 20 sin(2\(\pi\) \(\times\) 107 t) voltsThe modulated signal now contains the message signal with lower side band and upper ...

A message signal of frequency 20 kHz and peak voltage of 20 volt is used to modulate a carrier wave of frequency 1 MHz and peak voltage of 20 volt. The modulation index will be :

Given below are two statements :Statement I : A speech signal of 2 kHz is used to modulate a carrier signal of 1 MHz. The bandwidth requirement for the signal is 4 kHz.Statement II : The side band frequencies are 1002 kHz and 998 kHz.In the...

If a message signal of frequency 'fm' is amplitude modulated with a carrier signal of frequency 'fc' and radiated through an antenna, the wavelength of the corresponding signal in air is :

An audio signal vm = 20 sin 2\(\pi\)(1500t) amplitude modulates a carrier vc = 80 sin 2\(\pi\)(100,000t).The value of percent modulation is _________.

A signal of 0.1 kW is transmitted in a cable. The attenuation of cable is \(-\)5 dB per km and cable length is 20 km. The power received at receiver is 10\(-\)x W. The value of x is ________.[Gain in $$dB = 10{\log _{10}}\left( {{{{P_o}} \o...

What should be the height of transmitting antenna and the population covered if the television telecast is to cover a radius of 150 km? The average population density around the tower is 2000/km2 and the value of Re = 6.5 \(\times\) 106 m.

A carrier wave Vc(t) = 160 sin(2\(\pi\) \(\times\) 106t) volts is made to vary between Vmax = 200 V and Vmin = 120 V by a message signal Vm(t) = Am sin(2\(\pi\) \(\times\) 103t) volts. The peak voltage Am of the modulating signal is _______...

A carrier wave with amplitude of 250 V is amplitude modulated by a sinusoidal base band signal of amplitude 150V. The ratio of minimum amplitude to maximum amplitude for the amplitude modulated wave is 50 : x, then value of x is ___________...

Match List - I with List - II.List - I(a) 10 km height over earth's surface(b) 70 km height over earth's surface(c) 180 km height over earth's surface(d) 270 km height over earth's surfaceList - II(i) Thermosphere(ii) Mesosphere(iii) Strato...

A TV transmission tower antenna is at a height of 20 m. Suppose that the receiving antenna is at.(i) ground level(ii) a height of 5 m.The increase in antenna range in case (ii) relative to case (i) is n%.The value of n, to the nearest integ...

For VHF signal broadcasting, ___________ km2 of maximum service area will be covered by an antenna tower of height 30 m, if the receiving antenna is placed at ground. Let radius of the earth be 6400 km. (Round off to the Nearest Integer) (T...

A carrier signal C(t) = 25 sin(2.512 \(\times\) 1010t) is amplitude modulated by a message signal m(t) = 5 sin(1.57 \(\times\) 108t) and transmitted through an antenna. What will be the bandwidth of the modulated signal?

A 25 m long antenna is mounted on an antenna tower. The height of the antenna tower is 75 m. The wavelength (in meter) of the signal transmitted by this antenna would be :

Two identical antennas mounted on identical towers are separated from each other by a distance of 45 km. What should nearly be the minimum height of receiving antenna to receive the signals in line of sight? (Assume radius of earth is 6400 ...

An amplitude modulated wave is represented
by the expression vm = 5(1 + 0.6 cos 6280t)
sin(211 × 104 t) volts
The minimum and maximum amplitudes of the
amplitude modulated wave are, respectively

In a communication system operating at wavelength 800 nm, only one percent of source frequency is available as signal bandwith. The number of channels accomodated for transmitting TV signals of band width 6 MHz are (Take velocity of light c...

A signal Acoswt is transmitted using v0 sin \(\omega\)0t
as carrier wave. The correct amplitude
modulated (AM) signal is

The physical sizes of the transmitter and
receiver antenna in a communication system
are :-

The wavelength of the carrier waves in a
modern optical fiber communication network
is close to :

In a line of sight radio communication, a
distance of about 50 km is kept between the
transmitting and receiving antennas. If the
height of the receiving antenna is 70m, then the
minimum height of the transmitting antenna
should be :
(Radiu...

A 100 V carrier wave is made to vary between 160 V and 40 V by a modulating signal. What is the modulation index ?

To double the covering range of a TV transmittion tower, its height should be multiplied by :

In an amplitude modulator circuit, the carrier wave is given by, C(t) = 4 sin(20000 \(\pi\)t) while modulating signal
is given by, m(t) = 2 sin (2000 \(\pi\)t). The values of modulation index and lower side band frequency are :

An amplitude modulated signal is given by V(t) = 10[1 + 0.3cos(2.2 \(\times\) 104
t)] sin(5.5 \(\times\) 105
t). Here t is in
seconds. The sideband frequencies (in kHz) are, [Given \(\pi\) = 22/7]

An amplitude modulated signal is plotted below :

Which one of the following best describes the above signal ?

A TV transmission tower has a height of 140 m and the height of the receiving antenna is 40 m. What is the maximum distance upto which signals can be broadcasted from this tower is LOS (Line of Sight) mode ? (Given : radius of earth = 6.4 ×...

The modulation frequency of an AM radio station is 250 kHz, which is 10% of the carrier wave. If another AM station approaches you for license what broadcast frequency will you allot ?

A message signal of frequency 100 MHz and
peak voltage 100 V is used to execute
amplitude modulation on a carrier wave of
frequency 300 GHz and peak voltage 400 V.
The modulation index and difference between
the two side band frequencies ar...

Given below in the the left column are different
modes of communication using the kinds of
waves given the right column.

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A carrier wave of peak voltage 14 V is used for transmitting a message signal. The peak voltage of modulating signal given to achieve a modulation index of 80% will be :

The number of amplitude modulted broadcast stations that can be accomodated in a \(300\) \(kHz\) band width for the highest modulating frequency \(15\) \(kHz\) will be :

The carrier frequency of a transmitter is provided by a tank circuit of a coil of inductance 49 \(\mu\)H and a capacitance of 2.5 nF. It is modulated by an audio signal of \(12\) \(kHz.\) The frequency range occupied by the side bands is :...

A telephonic communication service is working at carrier frequency of 10 GHz. Only 10% of it is utilized
for transmission. How many telephonic channels can be transmitted simultaneously if each channel
requires a bandwidth of 5 kHz ?

A signal is to be transmitted through a wave of wavelength \(\lambda\), using a linear antenna. The length l of the antenna and effective power radiated Peff will be given respectively as :
(K is a constant of proportionality)

A signal of frequency 20 kHz and peak voltage of 5 Volt is used to modulate a carrier wave of frequency 1.2 MHz and peak voltage 25 Volts. Choose the correct statement.

In amplitude modulation, sinusoidal carrier frequency used is denoted by \({\omega _c}\) and the signal frequency is
denoted by \({\omega _m}\). The bandwidth (\(\Delta {\omega _m}\)) of the signal is such that \(\Delta {\omega _m}\) < < $$...

An audio signal consists of two distinct sounds : one a human speech signal in the frequency band of 200 Hz to 2700 Hz, while the other is a high frequency music signal in the frequency band of 10200 Hz to 15200 Hz. The ratio of the AM sign...

A modulated signal Cm(t) has the form Cm(t) = 30 sin 300 \(\pi\)t + 10 (cos 200 \(\pi\)t −cos 400 \(\pi\)t). The carrier frequency c, the modulating frequency (message frequency) f\(\omega\), and the modulation index \(\mu\) are respec...

Choose the correct statement :

A signal of \(5\) \(kHz\) frequency is amplitude modulated on a carrier wave of frequency \(2\) \(MHz.\) The frequencies of the resultant signal is/are :

A radar has a power of \(1kW\) and is operating at a frequency of \(10\) \(GHz.\) It is located on a mountain top of height \(500\) \(m.\) The maximum distance upto which it can detect object located on the surface of the earth (Radius of e...

This question has Statement - \(1\) and Statement - \(2\). Of the four choices given after the statements, choose the one that best describes the two statements.
Statement -\(1\) : Sky wave signals are used for long distance radio communica...