# Chapter 1: Overview of optical fiber communication¶

## Example 1.1, Page Number: 8¶

In [24]:
import math

#variable declaration
f1 = 100*1e3                #frequency1 = 100KHz
f2 = 1e9                    #frequency2 = 1GHz
T1 = 1.0/f1                 #Time period1 = 0.01ms
T2 = 1.0/f2                 #Time period2 = 1 ns

#calculation
phi = (0.25)*360.0          # Phase shift(degree)

#result
print "Phase shift = ",round(phi),"Degree","= ",round((round(phi)*math.pi)/180,4), "radian"

Phase shift =  90.0 Degree =  1.5708 radian


## Example 1.2, Page Number: 10¶

In [25]:
import math

#variable Declaration
flow=10*1e3                  #Lowest frequency(KHz)
fhigh=100*1e3                #Highest frequency(KHz)

#calculation
bandwidth=fhigh-flow         #bandwidth(KHz)

#result
print "Bandwidth=",bandwidth/1000 ,"KHz"

Bandwidth= 90.0 KHz


## Example 1.4, Page Number: 12¶

In [26]:
import math

#variable Declaration
B = 10*1e6                    # Bandwidth of noisy channel 1MHZ
S_N = 1                       # signal to noise ratio is 1

#calculation
C=B*(math.log(1+S_N)/math.log(2))   #capacity of channel(Mb/s)

#result
print "Capacity of channel =",C/(10*1e6),"Mb/s"

Capacity of channel = 1.0 Mb/s


## Example 1.5, Page Number: 12¶

In [27]:
import math

#variable Declaration
fLow = 3*1e6                        #low frequency = 3MHz
fHigh = 4*1e6                       #high frequency = 4MHz
SNR_dB = 20                         #signal to noise ratio 20 dB

#calculation
B = fHigh-fLow                             #Bandwidth(MHz)
S_N = 10**(SNR_dB/10)                      #signal to noise ratio
C = B*(math.log(1+S_N)/math.log(2))        #capacity of channel(Mb/s)

#result
print "Capacity of channel=",round(C/(1e6),1),"Mb/s"

Capacity of channel= 6.7 Mb/s


## Example 1.6, Page Number: 14¶

In [28]:
import math

#variable Declaration
P1 = 1                              # Let p1 be 1 watt
P2 = P1*0.5                         # P2 is half of p1 so 1/2

#calculation
Atten_dB = 10*(math.log(P2/P1)/math.log(10))     #attenuation or loss of power(dB)

#result
print "Attenuation loss =",round(Atten_dB,0), "dB"

Attenuation loss = -3.0 dB


## Example 1.7, Page Number: 14¶

In [29]:
import math

#variable Declaration
Loss_line1 = -9                #attenuation of signal between point 1 to 2 = 9 dB
Amp_gain2 = 14                 #Amplification of signal between point 2 to 3 = 14 dB
Loss_line3 = -3                #attenuation of signal between point 3 to 4 = 3 dB

#calculation
dB_at_line4 = Loss_line1+Amp_gain2+Loss_line3     #power gain(dB)

#result
print "Power gain for a signal travelling from point1 to another point4 = ",dB_at_line4, "dB"

Power gain for a signal travelling from point1 to another point4 =  2 dB