Post on 02-Jun-2018
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Roll No.
EXPERIMENT NO. 1
AIM: To simulate AM Modulation.
SOFTWARE USED:VisSim Comm 6.0
THEORY:-MODULATION:-It is defined as the process b !hich the base band si"nal #modulatin" si"nal$
modifies another hi"h fre%uenc si"nal called carrier. The carrier is hi"her in fre%uenc than thehi"hest base band si"nal fre%uenc. The baseband si"nal modifies the amplitude or fre%uenc or
phase of the carrier in modulation process.
AMPLITUDE MODULATION:-In amplitude modulation the amplitude of the carrier is &aried
in accordance to the instantaneous &alue of the modulatin" si"nal 'eepin" fre%uenc and phaseconstant.
(!here) c#t$ is carrier si"nal*
(!here) m#t$ is modulation si"nal*
(!here) #t$ is modulated si"nal*
MODULATION INDEX (m):-The relationship bet!een the amplitude of the modulatin" and
carrier si"nal is e+pressed in terms of their ratio 'no!n as modulation inde+ #m$ and is
mathematicall "i&en as m ,Vm-Vc (1.1)
The modulation inde+ lies bet!een 0 and
CALCULATION OF MODULATION INDEX (m):-
/i".#a$ Modulated a&e
/rom the abo&e fi"ure !e can !rite
(1.2)
= (1.3)
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Roll No.
/i".#a$ a&eform of AM
% D$4*m:-
/i".#b$ 3loc' 4ia"ram of /M
O5'65':
/i".#c$ 9utput of /M
R+,5': The /re%uenc Modulation has been simulated and &erified.
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Roll No.
W+&%*m:
/i".8#a$ a&eform of AS;
% $4*m
/i".8#b$ 3loc' 4ia"ram of AS;
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O5'65':
/i".8#c$ 9utput of AS;
R+,5':The Amplitude shift 'ein" #AS;$ has been simulated and studied.
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Roll No.
EXPERIMENT NO. ;
AIM : To stud and stimulate the /re%uenc shift 'ein" #/S;$ Modulation and
demodulation
S%&'*+ U,+: VisSim Comm. 6.0.
T+%*/:/re%uenc = Shift ;ein"#/S;$ is a fre%uenc modulation scheme in !hich di"ital information
is transmitted throu"h discrete fre%uenc chan"es of a carrier !a&e. The simplest /S; is binar
/S; #3/S;$. 3/S; literall implies usin" a pair of discrete fre%uencies to transmit binar #0s
and s$ information . ith this scheme ) the @ is called the mar' fre%uenc and the @0 is
called the space fre%uenc.
W+&%*m:
/i".#a$ a&eform of /S;
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%D$4*m:
/i".#b$ /re%uenc Shift ;ein" modulation and 4emodulation
O5'65':
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Roll No.
/i".#c$ 9utput of /S; Modulation and 4emodulation
R+,5': The /re%uenc Shift ;ein" #/S;$ Modulation and 4emodulation has
been studied 5 simulated.
EXPERIMENT NO.
A$m:To stud and simulate 2ulse 2osition Modulation.
S%&'*+ 5,+: VisSim Comm. 6.0
T+%*/:-2ulse
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Roll No.
O5'65':-
/i":?#b$ 9utput of 2ulse 2osition Modulation
R+,5':The 2ulse 2osition Modulation has been studied and simulated.
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Roll No.
EXPERIMENT NO. ?
A$m: To simulate 42S; Modulation.
S%&'*+ U,+:VisSim. Comm 6.0
T+%*/:4ifferential phase shift 'ein" #42S;$) a common form of phase modulation con&es data b
chan"in" the phase of carrier !a&e. In 2hase shift 'ein") Ei"h state contains onl one ccle but
42S; contains one and half ccle. Ei"h state is represented b a M in modulated si"nal and lo!
state is represented b a !a&e !hich appears li'e in modulated si"nal 42S; encodes t!o
distinct si"nals of same fre%uenc !ith B0 de"ree phase difference bet!een the t!o. This
e+periment re%uires t!o B0 de"ree out of phase carrier and modulatin" si"nals. Sine !a&e from
oscillator is selected as carrier si"nal. 4SJ con&erts 4C input &olta"e into pulse trains. These
pulse trains are ta'en as modulatin" si"nals. In actual practice modulatin" si"nal is di"ital form
of &oice or data. Sine !a&e is selected as carrier and B0 de"ree phase shift is obtained usin"
9pamp as sho!n in fi"ure belo!.
% D$4*m:
/i":B#a$ 42S; modulation
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O5'65':-
/i":B#b$ 9utput of 42S; modulation
R+,5':- The 42S; modulation has been studied and stimulated.
B 1 2 a " e
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Roll No.
EXPERIMENT NO. @
A$m:To simulate 42S; 4emodulation.
S%&'*+ U,+:VisSim. Comm 6.0
T+%*/:4ifferential phase shift 'ein" #42S;$) a common form of phase modulation con&es data b
chan"in" the phase of carrier !a&e. In 2hase shift 'ein") Ei"h state contains onl one ccle but
42S; contains one and half ccle. Ei"h state is represented b a M in modulated si"nal and lo!
state is represented b a !a&e !hich appears li'e in modulated si"nal 42S; encodes t!o
distinct si"nals of same fre%uenc !ith B0 de"ree phase difference bet!een the t!o. This
e+periment re%uires t!o B0 de"ree out of phase carrier and modulatin" si"nals. Sine !a&e from
oscillator is selected as carrier si"nal. 4SJ con&erts 4C input &olta"e into pulse trains. These
pulse trains are ta'en as modulatin" si"nals. In actual practice modulatin" si"nal is di"ital form
of &oice or data. Sine !a&e is selected as carrier and B0 de"ree phase shift is obtained usin" 9p