Chapter 9 Communication receivers

Example 9.1 Page no 318

In [1]:
#given
fl =220*10**6
fm =224*10**6
IF1 = 10.7*10**6
IF = 1.5*10**6

#Calculation
IF2 =IF1+IF
tune_l =fl+IF1
tune_m = fm+IF1
IF1_imgl = tune_l+IF1
IF2_imgm = tune_m+IF1

#Result
print"(a) The local oscillatior tuning range is ",tune_l/10**6,"to ",tune_m/10**6,"Mhz"
print"(b) Frequency of the second local oscillator is ",IF2/10**6,"MHz"
print"(c) First IF image range is ",IF1_imgl/10**6,"MHz to ",IF2_imgm/10**6,"MHz"

The local oscillatior tuning range is  230.7 to  234.7 Mhz
Frequency of the second local oscillator is  12.2 MHz
First IF image range is  241.4 MHz to  245.4 MHz

Example 9.2 Page no 324

In [1]:
#Given
R = 100*10**3
T = 273+25
B = 20*10**3
k = 1.38*10**-23

#Calculation
Vn=(4*k*T*B*R)**0.5

#Result
print"The noise voltage across 100k resistor is ",round(Vn*10**6,2),"microvolt"

The noise voltage across 100k resistor is  5.74 microvolt

Example 9.3 Page no 324

In [2]:
#Given
R=75
B=6*10**6  
T = 29+273
k =1.38*10**-23

#calculation
Vn = (4*k*T*B*R)**0.5

#Result
print"The input themal noise is ",round(Vn*10**6,2),"microvolt"

The input themal noise is  2.74 microvolt

Example 9.4 Page no 326

In [3]:
#Given
Tc=32.2
Tk=273+Tc
B =30*10**3
k =1.38*10**-23

#Calculation
Pn=k*Tk*B

#Result
print"The average noise power is ",round(Pn*10**16,2),"10**-16 W"

The average noise power is  1.26 10**-16 W

Example 9.5 Page no 329

In [6]:
#Given
SN_ip = 8
SN_op = 6.0

#Calculation
NR = SN_ip/SN_op
NF = 10*log10(NR)

#Result
print"The noise factor is ",round(NR,2)
print"The noise figure is ",round(NF,2),"dB"

The noise factor is  1.33
The noise figure is  1.25 dB

Example 9.6 Page no 330

In [23]:
#Given
R= 75.0
T=31+273
k=1.38*10**-23
B=6*10**6
Vs = 8.3*10**-6
NF=2.8

#Calculation
import math
Vn = math.sqrt(4*k*T*B*R)
Pn = Vn**2/R
Ps = Vs**2/R
SN = (Ps*10**12)/(Pn/10.0**12)
SN_dB =10*log10(SN)
NR = 10**0.28
SN_op = SN/NR
Tn = 290*(NR-1)

#Result
print"(a) The input noise power is ",round(Pn*10**12,1),"pW"
print"(b) The input signal power is ",round(Ps*10**12,3),"pW"
print"(c) Signal to noise ratio in decibels ",round(SN/10**24,2)
print"(d) The noise factor is ",round(NR,2)
print"(e) Signal to noise ratio of the amplifier is ",round(SN_op/10**24,2)
print"(f) The noise temperature of the amplifier ",round(Tn,0),"K"

(a) The input noise power is  0.1 pW
(b) The input signal power is  0.919 pW
(c) Signal to noise ratio in decibels  9.12
(d) The noise factor is  1.91
(e) Signal to noise ratio of the amplifier is  4.79
(f) The noise temperature of the amplifier  263.0 K