Chapter 17 : Satellite communication

Example 17.1 Page No : 547

In [1]:
import math 

# Variables
H = 10.**6;    #meter

# Calculations and Results
v = 20*10**6/math.sqrt(H+6.4*10**6);   #m/s
print 'a)velocity , v = %i m/s'%(v);
R = 6.4*10**6;    #data rate in bits per second
C = 2*math.pi*(H+R);    #circumference in m
print ' b)circumference , C = %i m'%(C);    #raunded value of C shown in book solution
T = C/v;
print ' c)The period is , T = %.2f seconds or %.2f minutes'%(T,T/60);

a)velocity , v = 7352 m/s
 b)circumference , C = 46495571 m
 c)The period is , T = 6324.08 seconds or 105.40 minutes

Example 17.2 Page No : 548

In [2]:
import math 

# Variables
L = 37;   #latitude in degree
R = 6400.;  
H = 36000.;  #from the text

# Calculations
del1 = math.atan(R*math.sin(L*math.pi/180)/(H+R*(1-math.cos(L*math.pi/180))))   #Declination angle

# Results
print 'The ange is %.2f degree'%(del1*180/math.pi);

The ange is 5.90 degree

Example 17.3 Page No : 552

In [3]:
import math 

# Variables
c = 3.*10**8;   #speed of light in m/s
f = 3.7*10**9;   #Hz

# Calculations and Results
lembda = c/f;   #m
print 'The wave length is %.4f cm '%(lembda*100)
theta_3dB = 8;    #degree
D = 70*lembda/theta_3dB     #m
print 'The diameter is, D =  %.4f m '%(D);
eta_1 = .6;     #illumination efficiency 
G = eta_1*(math.pi*D/lembda)**2;    #gain calculation
print 'The Gain is G =  %.2f '%(G)
G_dB = 10*math.log10(G);   #dB gain
print 'The Gain in dB is GdB) =  %.3f dB '%(G_dB)

The wave length is 8.1081 cm 
The diameter is, D =  0.7095 m 
The Gain is G =  453.38 
The Gain in dB is GdB) =  26.565 dB

Example 17.4 Page No : 553

In [4]:
import math 

# Variables
theta_3dB = 1.6;    # beamwidth in degree
eta_1 = .6;     #illumination efficiency 

# Calculations and Results
G = eta_1*48000/(theta_3dB)**2;    #gain calculation
print 'The Gain is G =  %.0f '%(G)
G_dB = 10*math.log10(G);   #dB gain
print 'The Gain in dB is GdB) =  %.1f dB '%(G_dB)

The Gain is G =  11250 
The Gain in dB is GdB) =  40.5 dB

Example 17.5 Page No : 554

In [5]:
import math 

# Variables
theta_3dB = .3;    # minimum practical beamwidth in degree
eta_1 = .6;     #illumination efficiency 

# Calculations and Results
G = eta_1*48000/(theta_3dB)**2;    #gain calculation
print 'The Gain is G =  %.0f '%(G)
G_dB = 10*math.log10(G);   #dB gain
print 'The Gain in dB is GdB) =  %.1f dB '%(G_dB)

The Gain is G =  320000 
The Gain in dB is GdB) =  55.1 dB

Example 17.6 Page No : 554

In [6]:
import math 

# Variables
c = 3*10**8;   #speed of light in m/s
f = 5.925*10**9;   #Hz

# Calculations and Results
lembda = c/f;   #m
print 'The wave length is %.3f cm '%(lembda*100)
theta_3dB = 1.6;    # beamwidth degree
D = 70*lembda/theta_3dB     #m
print 'The diameter is, D =  %.3f m '%(D);

The wave length is 5.063 cm 
The diameter is, D =  2.215 m

Example 17.7 Page No : 556

In [7]:
import math 

# Variables
l = 127.-70.2;     #Difference in longitude
L = 40.5    #Latitude of New York

# Calculations
d_km = 35.786*10**3*math.sqrt(1+0.42*(1-math.cos(L*math.pi/180)*math.cos(l*math.pi/180)));

# Results
print 'The distance is %.0f km '%(d_km)

The distance is 39932 km

Example 17.8 Page No : 556

In [8]:
import math 

# Variables
PtdBW = 20.
GtdB = 55.

# Calculations and Results
EIRP_dBW = PtdBW+GtdB;
print 'The EIRP for uplink earth station is %.0f dBW '%(EIRP_dBW)
l = 91-70.2;     #Difference in longitude
L = 40.5    #Latitude of New York
d_km = 35.786*10**3*math.sqrt(1+0.42*(1-math.cos(L*math.pi/180)*math.cos(l*math.pi/180)));
print 'The distance is %.0f km '%(d_km)

f = 6.125      #Uplink frequency in GHz
alfa1_dB = 20*math.log10(f)+20*math.log10(d_km)+92.44;    #Path loss
print 'The path loss is %.2f dB '%(alfa1_dB)

FdB = 3;    #noise figure in dB
F = 10**(FdB/10)   #absolute noise figure   (exact value)
Te = (F-1)*290;   #Noise temperature
print 'The Noise temperature of satellite reciever is %.0f K '%(Te)
Ti = 300;    #input noise temperature in K
Tsys = Ti+Te
print 'The system temperature of satellite reciever is %.0f K '%(Tsys)
G_dB = 27      #satellite reciever antwnna gain
GT = G_dB-10*math.log10(Tsys);     #G/T ratio in dB
print 'The G/T ratio for satellite reciever is %.2f dB/K '%(GT)
B = 36*10**6  ;#   Bandwidth  in Hz
L_misc = 1.6      #atmospheric loss
CN = EIRP_dBW-alfa1_dB+GT+228.6-10*math.log10(B)-L_misc;    #C/N in dB
print 'The carrier power to noise ratio at the satellite reciever is %.2f dB '%(CN)
#  Value of F is rouded to 2 in the text

The EIRP for uplink earth station is 75 dBW 
The distance is 37897 km 
The path loss is 199.75 dB 
The Noise temperature of satellite reciever is 0 K 
The system temperature of satellite reciever is 300 K 
The G/T ratio for satellite reciever is 2.23 dB/K 
The carrier power to noise ratio at the satellite reciever is 28.91 dB

Example 17.9 Page No : 557

In [9]:
import math 

# Variables
EIRP_dBW = 47.8;   #dBW
l = 91.-90;     #Difference in longitude
L = 32.    #Latitude of New York

# Calculations and Results
d_km = 35.786*10**3*math.sqrt(1+0.42*(1-math.cos(L*math.pi/180)*math.cos(l*math.pi/180)));
print 'The distance is %.0f km '%(d_km)

f = 3.9      #downlink frequency in GHz
alfa1_dB = 20*math.log10(f)+20*math.log10(d_km)+92.44;    #Path loss
print 'The path loss is %.2f dB '%(alfa1_dB)

F = 1.778   #absolute noise figure 
Te = (F-1)*290;   #Noise temperature
print 'The Noise temperature of satellite reciever is %.2f K '%(Te)
Ti = 150;    #input noise temperature in K
Tsys = Ti+Te
print 'The system temperature of satellite reciever is %.2f K '%(Tsys)
G_dB = 42      #satellite reciever antwnna gain
GT = G_dB-10*math.log10(Tsys);     #G/T ratio in dB
print 'The G/T ratio for satellite reciever is %.2f dB/K '%(GT)
B = 36*10**6  ;#   Bandwidth  in Hz
L_misc = 1      #atmospheric loss
CN = EIRP_dBW-alfa1_dB+GT+228.6-10*math.log10(B)-L_misc;    #C/N in dB
print 'The carrier power to noise ratio at the satellite reciever is %.1f dB '%(CN)

The distance is 36911 km 
The path loss is 195.60 dB 
The Noise temperature of satellite reciever is 225.62 K 
The system temperature of satellite reciever is 375.62 K 
The G/T ratio for satellite reciever is 16.25 dB/K 
The carrier power to noise ratio at the satellite reciever is 20.5 dB