Pulse waves: Modulation types - Physics Communication Systems, Physics, Class 12 Video Lecture

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from exam now so far we talked about the
modulation types in case of a sinusoidal
wave what about the pulse wave if we do
not have a sine wave instead if we have
a square wave or a rectangular wave what
happens to the modulation types there so
do we still have those three types of
modulation so let us have a look here
first let us see what is a pulse wave
what exactly is a but as I said before
also it is very similar to a square wave
just that it is not symmetrical like a
square wave so it is a non sinusoidal
wave similar to square wave it is also
known as a rectangular wave because when
I talk about the square wave it will be
somewhat like this like this weight that
this width everything will be same but
when I talk about rectangular wave it is
more like that right so this kind of
whales are known as a pulse waves a
pulse wave can be a rectangular wave it
can be a square wave so let us look at
the different types of modulation which
are possible in a pulse wave now what
are the different parameters of a pulse
wave because the type of one modulation
which are possible which would be
possible they will actually depend on
the parameters because modulation is
nothing but modification of a particular
parameter of a wave so in case of sine
wave those parameters their amplitude
frequency and phase so let us see what
are the important parameters of a pulse
wave when I talk of a pulse wave pulse
width or pulse duration is an important
parameter what is pulse width so this
width is meThe is known as pulse width
so this is a very important parameter to
describe a pulse wave so when the
modulation happens on the pulse width
that means if the pulse width of the
carrier wave gets modified as per the
message signal then we see that it is a
width modulation or a pulse duration
modulation which is often abbreviated as
PWM or PG n the next parameter is a
pulse amplitude so pulse amplitude again
is this distance this is the amplitude
so when that there is a change of the
amplitude we call it as pearls amplitude
modulation and a third one is a pulse
position for example this is a rise in
pulse right so the pulse rise this is
per pulse fall so these positions
actually denote the pulse position where
exactly the pulse rises where exactly
the pulse Falls so if there is a change
in these positions it is known as pulse
position modulation so these are the
three types of modulation of pulse rates
we are not getting into the detail of
each of these modulation because I hope
that with the help of the sinusoidal
waves we have already got an idea you
have got the concept what actually
happens during a modulation so I am NOT
getting into the details of each type of
pulse wave modulation so what was the
agenda of this topic we talked about
modulation why do we need modulation
what are the different types of
modulation so a last recap for the need
of modulation because the size of the
antenna prefers a high frequency signal
for transmission power radiated by an
antenna should be high for effective
transmission for that high frequency
signal is preferred mixing up signals
from different transmitters can be
avoided by using communication at high
frequencies and alerting a band of
frequencies to each message signal for
its transmission I have discussed each
of them in detail before so I hope that
it is clear to you so with this I will
end my discussion on modulation and I
will focus more on amplitude modulation
because so far we have talked about many
types of modulation right but at this
level we will not get into the details
of each type of modulation we will only
talk about amplitude modulation what we
will see is it till now I explained you
that different types of modulation with
the help of graphs right
now we will mathematically see what
happens during amplitude modulation
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