PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

446 Practical MATLAB® Applications for Engineers

Cw _ spectrum _ of _ carrier =

pi*Dirac(w-50)+pi*Dirac(w+50)

*********************************************************************

Mw _ spectrum _ of _ message =

3*pi*Dirac(w-5)+3*pi*Dirac(w+5)

*********************************************************************

MCw _ spectrum _ carry _ plus _ message =

3*pi*Dirac(w-5)+3*pi*Dirac(w+5)+pi*Dirac(w-50)+pi*Dirac(w+50)

**********************************************************************

AM _ DSB _ SC _ spectrum _ =

3/2*pi*Dirac(w-55)+3/2*pi*Dirac(w- 45)+3/2*pi*Dirac(w+45)+3/

2*pi*Dirac(w+55)

***********************************************************************

AM _ DSB _ WC _ spectrum _ =

3/2*pi*Dirac(w-55)+3/2*pi*Dirac(w-45)+5*pi*Dirac(w-0)+3/2*pi*Dirac(w+45)+

3/2*pi*Dirac(w+55)+5*pi*Dirac(w+50)

***********************************************************************

FM _ spectrum =

.615e-1*Dirac(w-55.)+.615e-1*Dirac(w+55.)-

.615e-1*Dirac(w-45.)-.615e-1*Dirac(w+45.)+

.405*Dirac(w-60.)+.405*Dirac(w+60.)+.405*Dirac(w-40.)+

.405*Dirac(w+40.)+.970*Dirac(w-65.)+

.970*Dirac(w+65.)-.970*Dirac(w-35.)-.970*Dirac(w+35.)+1.35*Dirac(w-70.)+

1.35*Dirac(w+70.)+

1.35*Dirac(w-30.)+1.35*Dirac(w+30.)+1.15*Dirac(w-75.)+1.15*Dirac(w+75.)-

1.15*Dirac(w-25.)-1.15*Dirac(w+25.)

*************************************************************************

5

5

0 5

0

0

10

0

0.05 0.15

1.5 50

0

0

0 0

0

5

10

0.5

4

2

− 2

− 50

0 50

0

− 50

− 4

0

1

0.1 0.2

1

12

23

− 5

− 1

− 5

time (sec)

4

2

message(t)

carrier(t)

carrier(t)+message(t)

mag[M(w)]

mag[C(w)]

mag[M(w)]+C(w)]

frequency w (rad/sec)

TIME DOMAIN FREQUENCY DOMAIN

FIGURE 4.87
Time and frequency domain of parts a, b, and c of Example 4.22.