Chapter 3:Advanced Radars

Example 1, Page no 104

In [3]:
import math
# Variable Declaration
PRF   = 1500;                                 # pulse repetitive frequency in Hz
lamda = 3*10**-2;                             # wavelength in m;

# Calculations
# n = 1 gives lowest blind speed
n=1;

Vb = n*(lamda/2)*PRF;                         # blind speed in m/s

#Result
print 'Lowest Blind Speed is',Vb,'m/s';

Lowest Blind Speed is 22.5 m/s

Example 2, Page no 105

In [15]:
import math;
# Variable Declaration
PRF= 1000;                          # pulse repetitive frequency in Hz
Fd = 1000;                          # doppler frequency in Hz;
F  = float(10*10**9);                      # operating frequency of radar in Hz;
Vo = float(3*10**8);                       # velocity in m/s

# Calculations
lamda = Vo/F;
Va    = (Fd*lamda)/2;             # speed of automobile in m/s
Va1   = Va*18/5;                  # speed of automobile in kmph

# Result
print 'Speed of automobile is' ,Va,'m/s', 'or',Va1,'kmph';

Speed of automobile is 15.0 m/s or 54.0 kmph

Example 3, Page no 105

In [18]:
import math
# Variable declaration
PRF= 1000;                            # pulse repetitive frequency in Hz
F  = 10*10**9;                        # operating frequency of radar in Hz;
Vo = 3*10**8;                         # velocity in m/s

# Calculations
lamda = Vo/F;
                                      # Blind Frequency is given by Fn = n*PRF;
n1 = 1;
n2 = 2;
n3 = 3;
F1 =n1*PRF;                          # blind frequency for n=1 in Hz; 
F2 =n2*PRF;                          # blind frequency for n=2 in Hz; 
F3 =n3*PRF;                          # blind frequency for n=3 in Hz; 

# Result
print 'Lowest three Blind Frequencies are',F1/1000, 'KHz',F2/1000,'KHz' ,'and',F3/1000,'KHz';

Lowest three Blind Frequencies are 1 KHz 2 KHz and 3 KHz

Example 4, Page no 105

In [1]:
import math;
# Variable declaration
F  = float(10*10**9);                             # operating frequency in Hz
PRF= float(800);                                  # pulse repetitive frequency in Hz
Vo = 3*10**8;                               # velocity in m/s; 
n1 = 1;
n2 = 2;
n3 = 3;

# Calculations

lamda = Vo/F;                               # Wavelength in m

# blind speed Vb = n*(lamda/2)*PRF in m/s

Vb1 = n1*(lamda/2)*PRF;                     #first blind speed in m/s;
Vb2 = n2*(lamda/2)*PRF;                     #second blind speed in m/s;
Vb3 = n3*(lamda/2)*PRF;                     #third blind speed in m/s;

#Result
print 'First Blind Speed is',Vb1,'m/s'
print 'Second Blind Speed is',Vb2,'m/s'
print 'Third Blind Speed is',Vb3,'m/s'
print 'NOTE: IN TEXT BOOK THIRD BLIND SPEED IS WRONGLY PRINTED AS 48 m/s';

First Blind Speed is 12.0 m/s
Second Blind Speed is 24.0 m/s
Third Blind Speed is 36.0 m/s
NOTE: IN TEXT BOOK THIRD BLIND SPEED IS WRONGLY PRINTED AS 48 m/s

Example 5,Page No:106

In [2]:
import math

#variable declaration
F          = 10*10**9;    #operating frequency in Hz
Vo         = 3*10**8;     #velocity in m/s; 
Vb1        = 20;          #lowest(first) blind speed in m/s
n          = 1 ;          #since first blindspeed

#Calculations

lamda      = Vo/float(F);        #Wavelength in m

# blind speed Vb = n*(lamda/2)*PRF in m/s

PRF       = (2*Vb1)/float((n*lamda));    #pulse repetitive frequency in Hz

#result

print'Pulse Repetitive Frequency is %3.2f'%(PRF/1000),'KHz';

Pulse Repetitive Frequency is 1.33 KHz

Example 6,Page No:106

In [3]:
import math

#variable expression
lamda     = 3*10**-2;        #wavelength in m
PRF       = 1000;            #pulse repetitive frequency in Hz
Vo        = 3*10**8;         # velocity in m/s

#Calculations

Ruamb     = (Vo)/float(2*PRF);     #max unambiguous range in m

#result

print'Maximum unambiguous range is %g'%(Ruamb/1000),'Kms';

Maximum unambiguous range is 150 Kms

Example 7,Page No:106

In [4]:
import math

#variable declaration
n1   = 1 ;                #since first blindspeed
n3   = 3 ;                #since third blindspeed

#Calculations


# blind speed Vb1 = n1*(lamda_1/2)*PRF1 in m/s
# blind speed Vb3 = n3*(lamda-2/2)*PRF2 in m/s
#here PRF1 = PRF2 = PRF
#if Vb1=Vb3 then
#1*(lamda_1/2)*PRF  =  3*(lamda_2/2)*PRF
#lamda_1/lamda_2    = 3/1;
#lamda = C/F;
#therefore F1/F2 = 1/3 ;


#result
print'Ratio of Operating Frequencies of two Radars are (F1/F2) = 1/3';

Ratio of Operating Frequencies of two Radars are (F1/F2) = 1/3

Example 8,Page No:107

In [5]:
import math

#variable declaration
Vb1     = 20;            #first blind speed in m/s
Vb2     = 30;            #second blind speed in m/s
n1      =1 ;             #since first blindspeed
n1      =2 ;             #since second blindspeed
lamda   = 3*10**-2;      #wavelength in m

#Calculations

PRF1 = (2*Vb2)/float(n1*lamda);         #pulse repetitive frequency in Hz of  First Radar;

PRF2 = (2*Vb2)/float(n1*lamda);          #pulse repetitive frequency in Hz of Second Radar;


#result
print'Ratio of pulse repetitive frequencies of the Radars is PRF1/PRF2 = %g'%(PRF1/PRF2);

Ratio of pulse repetitive frequencies of the Radars is PRF1/PRF2 = 1

Example 9,Page No:107

In [2]:
import math

#variable declaration
F       = 6*10**9;        #operating frequency in Hz
PRF     = 1000;           #pulse repetitive frequency in Hz
Vo      = 3*10**8;        #velocity in m/s; 
n2      = 2;              # n value for second blind speed
n3      = 3;              # n value for third blind speed

#Calculations

lamda = Vo/float(F);             #Wavelength in m

# blind speed Vb = n*(lamda/2)*PRF in m/s

Vb2      = n2*(lamda/float(2))*PRF;        #second blind speed in m/s;
Vb21     = Vb2*18/float(5);               #second blind speed in kmph; 
Vb3      = n3*(lamda/float(2))*PRF;        #third blind speed in m/s;
Vb31     = Vb3*18/float(5);           #/third blind speed in kmph;

#result
print'Second Blind Speed is %g'%Vb21,'kmph';
print'Third Blind Speed is %g'%Vb31,'kmph';

Second Blind Speed is 180 kmph
Third Blind Speed is 270 kmph

Example 10,Page No:108

In [4]:
import math

#variable declaration
r             = 0.5;            #Antenna Radius in m
f             = 8*10**9          #operating frequency in Hz
Vo            = 3*10**8;         #vel. of EM wave in m/s
RCS           = 5;              # Radar cross section in m^2
D             = 1;              # antenna diameter in m
F             = 4.77;              # noise figure in dB
Rmax          = 12*10**3         # Radar range
BW            = 500*10**3;       # bandwidth

#Calculation
F1            = 10**(F/float(10));       # antilog calculation
lamda         = Vo/float(f);                     # wavelength

#Rmax        = 48*((Pt*D^4*RCS)/(BW*lamda*lamda(F-1)))^0.25

Pt            = ((Rmax/48)**(4))*((BW*lamda*lamda*(F1-1))/float((D**(4)*RCS)))

#result

print'Peak Transmitted Power is %e'%Pt;
print'Note: Calculation error in textbook at Pt 10^12 missing';

Peak Transmitted Power is 1.098173e+12
Note: Calculation error in textbook at Pt 10^12 missing