# Chapter 3 Amplitude modulation-Reception¶

## Example 3.1 Page no 120¶

In :
# given
fr=550*10**3                           #frequency, Hz
L=10.0*10**-6                          #inductor, H
fr1=1550*10**3

#calculation
import math
a=fr*2*math.pi
x=fr1*2*math.pi
b=1/a
y=1/x
C1=((b)**2/L)
C2=((y)**2/L)
fr2=1100*10**3
BW=10.0*10**3
Q=(fr2/BW)
BW1=(fr1/Q)
BW2=(fr/Q)

#result
print"(a) required range of capacitance is from ",round(C2,12),"F","to",round(C1,12),"F"
print"(b) Q= ",Q
print"(c) Bandwidth of receiver at 1550 KHz = ",round(BW1,2),"Hz"
print"Babdwidth of receiver at 550 KHz = ",BW2,"Hz"

(a) required range of capacitance is from  1.054e-09 F to 8.374e-09 F
(b) Q=  110.0
(c) Bandwidth of receiver at 1550 KHz =  14090.91 Hz
Babdwidth of receiver at 550 KHz =  5000.0 Hz


## Example 3.2 Page no 134¶

In :
# given
f=620*10**3                                    #frequency, Hz
IF=455*10**3

#calculation
LO=f+IF
X=IF+LO
# image frequency of local oscillator
#station frequency = 620 kHz

#Result
print"LO =  Hz",LO
print"X-1075kHz=",X,"Hz"

LO =  Hz 1075000
X-1075kHz= 1530000 Hz


## Example 3.3 Page no 150¶

In :
#Given
V=8*10**-6                         #microvolts
R=50                               #input resistance, ohm

#Calculation
import math
P=(V**2)/R
dBm=10*math.log10(P/0.001)
dBW=10*math.log10(P/1)
a=(-89+8+3+24+26+26-2+34)
x=(a/10)
y=10**x
z=y*0.001

#Result
print"input power  is= ",P,"W"
print"dBm = ",round(dBm,0),"dBm"
print"dBW = ",round(dBW,0),"dBw"
print"Pout(dBm) =",a," dBm into speaker"
print"Pout(dBW) =",z,"W"

input power  is=  1.28e-12 W
dBm =  -89.0 dBm
dBW =  -119.0 dBw
Pout(dBm) = 30  dBm into speaker
Pout(dBW) = 1.0 W