Chapter 2:Basic Radars

Example 1,Page No:74

In [4]:
import math

#variable declaration

Tdelay      = 200*10**-6;       #time delay in sec
Vo          = 3*10**8;          #velocity in m/s

#Calculations

R           = (Vo*Tdelay)/float(2);        #Range of the target in kms


#result

print'Range of the target is %g'%(R/1000),'Kms';

Range of the target is 30 Kms

Example 2,Page No:74

In [2]:
import math

#variable declaration
Pt      = 5000;         #Peak tx power in watts
Pav     = 1000;         #Average Power
PRF1    = 10;           #Pulse repetition frequency in khz
PRF2    = 20;           #Pulse repetition frequency in khz

#Calculations

D      = Pav/float(Pt);        #Duty cycle
PRI1   = 1/float(PRF1);        #Pulse repetitive interval in  msec
PRI2   = 1/float(PRF2);        #Pulse repetitive interval in  msec
PW1    = D*PRI1;               #Pulse Width in msec
PW2    = D*PRI2;               #Pulse Width in msec
PE1    = Pt*PW1;               #Pulse Energy in joules
PE2    = Pt*PW2;               #Pulse Energy in joules

#result
print'Duty cycle is ',D; 
print'pulse repetition interval 1 is ',PRI1,'msec';
print'pulse repetition interval 2 is ',PRI2,'msec';
print'Pulse Width1 is ',PW1*1000,'usec';
print'Pulse Width2 is ',PW2*1000,'usec';
print'Pulse Energy1 is ',PE1/1000,'J';
print'Pulse Energy2 is ',PE2/1000,'J';

Duty cycle is  0.2
pulse repetition interval 1 is  0.1 msec
pulse repetition interval 2 is  0.05 msec
Pulse Width1 is  20.0 usec
Pulse Width2 is  10.0 usec
Pulse Energy1 is  0.1 J
Pulse Energy2 is  0.05 J

Example 3,Page No:75

In [4]:
import math

#variable declaration
UR    = 200;                 #unambiguous range in kms
BW   = 1*10**6;                  #bandwidth in hz
V0   = 3*10**8;                  #velocity in m/s

#Calculations

PRF    = V0/float((2*UR*10**3));          #pulse repetition frequency in hz
PRI    = 1/float(PRF);                    #pulse repetition interval in sec
RR     = V0/float((2*BW));                #Range Resolution in mts
PW     = float(2*RR)/float((V0));              #pulse width

#Calculations

print'pulse repetition frequency is ',PRF ,'Hz';
print'pulse repetition interval is %3.3g'%(PRI*1000),'msec';
print'Range Resolution is ',RR,'m';
print'pulse width is %3.1f'%(PW*10**6),'usec';

pulse repetition frequency is  750.0 Hz
pulse repetition interval is 1.33 msec
Range Resolution is  150.0 m
pulse width is 1.0 usec

Example 4,Page No:76

In [5]:
import math

#variable declaration
Pt     =50000;             #peal power in watts
PRF    =1000;              #pulse repetitive frequency in hz
PW     =0.8;               #pulse width in usec
 
#Calculations

D     = PW*PRF*10**-6;          #duty cycle 
Pav   = Pt*D;                   #average power

#result
print'Duty cycle is %g'%D;
print'Average power is %g'%Pav,' Watts';

Duty cycle is 0.0008
Average power is 40  Watts

Example 5,Page No:76

In [7]:
import math

#variable declaration
Vo    = 3*10**8;              #velocity in m/s
Pt    = 1*10**6;              #peak power in watts
PW    = 1.2*10**-6;           #pulse width in sec
PRI   = 1*10**-3;             #pulse repetition interval in sec

#Calculations

PRF    = 1/float(PRI);               #pulse repetition frequency in hz
Pav    = Pt*PW*PRF;           #average power in watts
D      = Pav/float(Pt);              #Duty cycle;
Rmax   = Vo/float(2*PRF);          #maximum range of the radar in m

#result

print'pulse repetition frequency is %g'%(PRF/1000),' KHz';
print'average power is %g'%(Pav/1000),'KW';
print'Duty cycle = %3.2e'%D;
print'Maximum range of the radar is %g '%(Rmax/1000),'Km';

pulse repetition frequency is 1  KHz
average power is 1.2 KW
Duty cycle = 1.20e-03
Maximum range of the radar is 150  Km

Example 6,Page No:77

In [27]:
import math

#variable declaration
PW     = 2*10**-6;          #pulse width in sec
PRF    = 800;               #pulse repetition frequency in KHz
V0     = 3*10**8;          #velocity in m/s

#Calculations

Ru    = V0/float(2*PRF);      #unambigious range in mts
RR    =(V0*PW)/float(2);             #Range resolution in m

#result
print'unambigious range is %g'%(Ru/1000),'Km';
print'Range resolution is %g '%RR,'m';
   

unambigious range is 187.5 Km

 Range resolution is 300  m

Example 7,Page No:77

In [28]:
import math

#variable declaration
Rmax     =  500;             #maximum range in kms
V0       =  3*10**8;         #velocity in m/s;

#calculations

PRF     = (V0/float(2*Rmax*10**3));     #pulse repetitive frequency in Hz


#result
print'pulse repetitive frequency is %g'%PRF,'Hz';

pulse repetitive frequency is 300 Hz

Example 8,Page No:77

In [9]:
import math

#variable declaration
F          = 9;              # Noise figure in dB
BW         = 3*10**6;        # Bandwidth
To         = 290;            # Temperature in kelvin
K          = 1.38*10**-23;   # Boltzman constant

#Calculations

F1         = 10**(F/float(10));    #antilog calculation
Pmin       = (K*To*BW)*(F1-1);     #minimum receivable power

#result

print'Minimum receivable power Pmin = %3.3g'%(Pmin*10**12),'pW';
print'Note: Calculation error at Pmin in textbook';

Minimum receivable power Pmin = 0.0834 pW
Note: Calculation error at Pmin in textbook

Example 9,Page No:77

In [12]:
import math

#variable declaration

Pt      = 500000;            #peal power in watts
F       = 10*10**9;          #operating frequency in hz
MRP     = 0.1*10**-12;       #minimum receivable power in pico watts
Ac      = 5;                 #capture area of antenna in m^2;
RCS     = 20;                #radar cross sectional area in m^2;
Vo      = 3*10**8;           #velocity in m/s

# calculations

lamda =Vo/float(F);
Rmax=((Pt*Ac*Ac*RCS)/float((4*math.pi*lamda*lamda*MRP)))**float(0.25);

#result

print'Maximum Radar Range is %g '%(Rmax/1000),'kms';

Maximum Radar Range is 685.681  kms