Answer / vineeth

Modulation is needed in a communication system to achieve
the following basic needs.such as
1)multiplexing
2)practicability of antennas

where the multiplexing helps in transmitting a number of
messages simultaneously over a single channel and therefore
the number of channels needeed will be less.This reduces
the cost of the installation and maintainance of more
channels.

Answer / s.bhuvaneswari

1.reduction of antenna hieght.
2.improvement in noise performance.
3.reduction in number of repeaters used.
4.to strengthen the weak signals.

Answer / nipuna

Problems will occur in the following areas if the base band
signal(information signal)is transmitted as it is,without
modulation.
1.Antenna Height
2.Narrow Banding
3.Poor radiation and penetration
4.Diffraction angle
5.Multiplexing

So Modulation is necessary for the transmission of low
frequency information signal from one site to another in
good quality.

Answer / atul shrivastava

modulation is a process in which the lower frequencey
signal called message signan and higher frequencey signal
called carrier signal is mixed to achive effectively
radiated signal.The need of modulation in communication
system is to achive the followig :-
1)multiplxing
2)practicability of antinnas.

Answer / mekala

Reduce antenna height
Avoid Interference
Reduction in Noise
Multiplexing is Possible

Answer / vikrant

Modulation is needed because:-

1) At low frequency there is very high attenuation.
2) we increase the frequeny and thus decrease the
attenuation of signal, thus making it viable to be
transmitted over lon distance.

Answer / amal dev.p

1.Long distance transmission:-
The capability of a wave to travel is directly
proportional to the wavelength,so increase in wavelength
increase the distance that covered by the wave.
2.Noise reduction:-
Noise is a low frequency signal so its tendency to mix with
high frequency signal is low.
3.Height of antenna:-
Height H=(wavelength)/4 but frequency F=c/(wavelength)
where c=3*10^8
so increase in wavelength decrease the height of antenna.
4.Adjacent channel reduction:-
All senders use signals of approximately same(with point
difference)wavelength.So there is chance for interfering of
waves so mixing this modulating wave with a high frequency
carrier wave increase the difference between the wavelength
of adjacent channels.

Answer / adeeb

1.Security.
2.Reduce the height of antenna.
3.Multiplexing.
4.To increase the range of communication.
5.Reduce height of Antenna.
6.Avoids mixing of signals.
7.Improve quality of reception.

Answer / ranjini

• , modulation can be used as a technique to conceal
the contents of the message being transmitted (for privacy
reasons). It is the case of the scattered spectrum
communications, which is relatively widely used in the
military communication appliances. The concept of scattered
spectrum came first during the 2nd world war, when the
spies in the French Resistance used multiple frequencies to
broadcast their messages to the Allies. The frequencies
were used according to a previously agreed protocol. This
way, their communication was less prone to be intercepted
by the Nazi's.

Answer / rohan mehta

Modulation is the process of supreimposing a baseband
signal(i.e low-frequency signal) on a high frequency carrier
signal.
1)Reduction in height of antenna.
2)Avoids mixing of signals.
3)Increase the range of communication.
4)Multiplexing is possible.
5)Improves quality of recepition.

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