Chapter 3 Amplitude modulation fundamentals

Example 3.1 page no 99

In [1]:
#Given
Vmax = 5.9
Vmin = 1.2

#Calculation
m = (Vmax-Vmin)/(Vmax+Vmin)
Vc = (Vmax+Vmin)/2.0
Vm = (Vmax-Vmin)/2.0
m = Vm/Vc

#Result
print"(a) The modulation index is ",round(m,2)
print"Vc= ",Vc,"Vm= ",Vm,"(for 2 volt/div on verticle scale)"

The modulation index is  0.66
Vc=  3.55 Vm=  2.35 (for 2 volt/div on verticle scale)

Example 3.2 page no 102

In [2]:
#Given
frq =980*10**3
frq_range = 5*10**3

#Calculation
fusb = frq+frq_range
flsb = frq-frq_range
bw=fusb-flsb

#Result
print"The upper sideband is at ",fusb/10**3,"Khz"
print"Lower sideband is at ",flsb/10**3,"Khz"
print"the babdwidth is ",bw/10**3,"KHz"

The upper sideband is at  985 Khz
Lower sideband is at  975 Khz
the babdwidth is  10 KHz

Example 3.3 page no 106

In [3]:
#Given
Pc = 30
m=0.85

#Calculation
Pt = Pc*(1+ (m**2/2.0))
Psb_both =Pt-Pc
Psb_one = Psb_both/2.0

#Result
print"The total power is ",round(Pt,1),"watt" 
print"The power in one sideband is ",round(Psb_one,1),"Watt"

The total power is  40.8 watt
The power in one sideband is  5.4 Watt

Example 3.4 page no 108

In [6]:
#Given
R = 40
I = 4.8
m=0.9

#Calculation
Pc = I**2*R
Pt = (I*(1+(m**2/2.0))**0.5)**2*R
Psb = Pt-Pc

#Result
print"(a) The carrier power is ",Pc," watt"
print"(b) Total power = ",round(Pt,0),"watt"
print"(c) Sideband Power = ",round(Psb,1),"watt"

(a) The carrier power is  921.6  watt
(b) Total power =  1295.0 watt
(c) Sideband Power =  373.2 watt

Example 3.5 page no 108

In [7]:
#given
It = 5.1
Ic =4.8

#Calculation
m=(2*((It/Ic)**2-1))**0.5

#Result
print"The percentage of modulation is ",round(m*100,0)

The percentage of modulation is  51.0

Example 3.6 page no 109

In [8]:
#Given
m = 0.9
Pc = 921.6

#calculation
Psb = (m**2*Pc)/4.0

#Result
print"The power in one sideband ",round(Psb,1),"Watt"

The power in one sideband  186.6 Watt

Example 3.7 page no 113

In [9]:
#Given
Vpp = 178
R = 75.0

#Calculation
Vp =Vpp/2.0
Vrms = 0.707*Vp
PEP =(Vrms**2/R)

#Result
print"The peak envelop power is ", round(PEP,1),"Watt"

The peak envelop power is  52.8 Watt

Example 3.8 page no 113

In [10]:
#Given
Vs =24
Im =9.3

#Calculation
PEP = Vs*Im 
Pavg1 = PEP/3.0
Pavg2 = PEP/4.0

#Result
print"(a) The peak envelope power is ",PEP,"watt"
print"(b) Average power of transmitter is ",Pavg2,"watt to",Pavg1,"watt"

(a) The peak envelope power is  223.2 watt
(b) Average power of transmitter is  55.8 watt to 74.4 watt