Added(A)/Deleted(D) following books

 A  Electronic_Communication_by_D._Roddy/Chapter10_Angle_Modulation.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter11_Pulse_Modulation.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter12_Digital_Communications.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter13_Transmission_Lines_And_Cables.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter14_WaveGuides.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter15_Radio_Wave_Propogation.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter16_Antennas.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter17_Telephone_Systems.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter18_Fascimile_and_Television.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter19_Satellite_Communications.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter1_Passive_Circuits.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter20_Fibre_Optic_Communication.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter2_Waveform_Spectra.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter4_Noise.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter5_Tuned_Small_Signal_Amplifiers,_Mixers_and_Active_Filters.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter6_Oscillators.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter7_Receivers.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter8_Amplitude_Modulation.ipynb
A  Electronic_Communication_by_D._Roddy/Chapter9_Single_Sideband_Modulation.ipynb
A  Electronic_Communication_by_D._Roddy/screenshots/1.png
A  Electronic_Communication_by_D._Roddy/screenshots/12.png
A  Electronic_Communication_by_D._Roddy/screenshots/9.png
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter11_Control_of_DC_Motors_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter12_Controllers_and_Their_Optimisation_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter13_Choppers_and_Transportation_system_Application_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter15_The_AC_motor_control_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter16_Faults_and_Protection_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter3_Fabrication_and_Thermal_characteristics_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter4_Series_and_Parallel_Connection_of_Thyristors_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter5_Line_Commutated_converters_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter7_Inverter_Circuits_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter8_Harmonic_and_PowerFactor_with_the_converter_system_1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/Chapter_2_The_Device__1.ipynb
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/screenshots/11.JPG
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/screenshots/15.JPG
A  Thyristors_Theory_And_Applications_by_R._K._Sugandhi_And_K._K._Sugandhi/screenshots/8.JPG

22 files changed, 4369 insertions, 0 deletions

diff --git a/Electronic_Communication_by_D._Roddy/Chapter10_Angle_Modulation.ipynb b/Electronic_Communication_by_D._Roddy/Chapter10_Angle_Modulation.ipynb
new file mode 100644
index 00000000..5311facc
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter10_Angle_Modulation.ipynb
@@ -0,0 +1,109 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter10 Angle Modulation"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 10.12.1,Pg.no.343"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The equivaent tuning capacitance is 6e-10 F\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "p=10.0\n",
+    "t=0.3*10**-6\n",
+    "gm=0.002\n",
+    "q=1/p\n",
+    "f_max=q/(2*pi*t)\n",
+    "Z2=p/gm\n",
+    "R2=Z2          #Z2 is resistance\n",
+    "#Determination of equivalent tuning capacitance\n",
+    "C1=t/R2\n",
+    "Ceq=gm*t\n",
+    "print 'The equivaent tuning capacitance is',Ceq,'F'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 10.13.1,Pg.no.349"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "fo is best obtained by using two tripler 79.1 Mhz\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "del_phi_d=12.0\n",
+    "f_min=100.0\n",
+    "del_f_max_allow =15000.0\n",
+    "del_phi_rad=(12*pi)/180\n",
+    "del_f_max=del_phi_rad*f_min\n",
+    "#Determination of freq deviation\n",
+    "N=del_f_max_allow/del_f_max\n",
+    "l=del_f_max*729       #using six tripler\n",
+    "f=0.1*729\n",
+    "#Determination of signal oscillator signal\n",
+    "fo=152-f\n",
+    "print 'fo is best obtained by using two tripler',fo,'Mhz'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter11_Pulse_Modulation.ipynb b/Electronic_Communication_by_D._Roddy/Chapter11_Pulse_Modulation.ipynb
new file mode 100644
index 00000000..f9a35e7b
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter11_Pulse_Modulation.ipynb
@@ -0,0 +1,101 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter11 Pulse Modulation"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 11.3.1,Pg.no.392"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The no . of bits per code word is 7.512\n",
+      "Rounded off to 8\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "SNR=40.0\n",
+    "#a) Determination of no . of bits /code\n",
+    "n=(SNR -(10*math.log10(3))-(-10))/(20*math.log10(2))\n",
+    "n=round(n,3)\n",
+    "print 'The no . of bits per code word is',n\n",
+    "print 'Rounded off to 8'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 11.3.2,Pg.no.393"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a)The transmission BW is 64000.0 Hz\n",
+      "b)The quantization S/N ration is 48.0\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "q=1.0\n",
+    "W=4*10**3\n",
+    "n=8.0\n",
+    "#a) Determination of Tx Bandwidth\n",
+    "B=(1+q)*W*n\n",
+    "print 'a)The transmission BW is',B,'Hz'\n",
+    "#b) Determination of quantization S/N ratio\n",
+    "SN_dB=6*n\n",
+    "print 'b)The quantization S/N ration is',SN_dB"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter12_Digital_Communications.ipynb b/Electronic_Communication_by_D._Roddy/Chapter12_Digital_Communications.ipynb
new file mode 100644
index 00000000..6ee4bd31
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter12_Digital_Communications.ipynb
@@ -0,0 +1,334 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter12 Digital Communications"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 12.4.1,Pg.no.419"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 47,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a= 1.0\n",
+      "b= 6.33 *10**-5\n",
+      "The bit error probability 3.17 *10**-5\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt,erf,erfc\n",
+    "Vs_Vn=4   #SNVR \n",
+    "a=erf(4/sqrt(2))\n",
+    "b=erfc(4/sqrt(2))*10**5\n",
+    "Pbe=(0.5)*(b)  #bit error probability\n",
+    "a=round(a,2)\n",
+    "b=round(b,2)\n",
+    "print 'a=',a\n",
+    "print 'b=',b,'*10**-5'\n",
+    "Pbe=round(Pbe,2)\n",
+    "print 'The bit error probability',Pbe,'*10**-5'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 12.4.2,Pg.no.420"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 43,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The bit error probability 0.309\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "A=4     #max value of received signal voltage\n",
+    "Vn=0.5  #rms noise voltage\n",
+    "Vth=2   #Threshold voltage for the comparator\n",
+    "b=erfc(Vn/sqrt(2))\n",
+    "Pbe=(0.5) * b  #bit error probability\n",
+    "Pbe=round(Pbe,3)\n",
+    "print 'The bit error probability',Pbe "
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 12.4.3,Pg.no.421"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 41,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Bit Probabilty,Pbe1= 0.0024\n",
+      "Bit Probability,Pbe2= 0.0232\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import erfc\n",
+    "SNR=9.0   #SNR in dB\n",
+    "#conversion of dB to power ratio\n",
+    "p=10**(9/10)  #for Polar\n",
+    "Pbe1=0.5*erfc(sqrt(7.94/2))\n",
+    "Pbe1=round(Pbe1,4)\n",
+    "print 'Bit Probabilty,Pbe1=',Pbe1\n",
+    "#for Unipolar\n",
+    "Pbe2=0.5* erfc(sqrt(7.94)/2)\n",
+    "Pbe2=round(Pbe2,4)\n",
+    "print 'Bit Probability,Pbe2=',Pbe2"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 12.5.1,Pg.no.423"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 37,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The bit error probability 3.5 *10**-5\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "Pavg=6.0*10**-12    #in W\n",
+    "d=0.02*10**-6     #pulse duration in sec\n",
+    "T=550.0           #equivalent noise temp in K\n",
+    "Eb=Pavg*d         #avg energy per pulse\n",
+    "No=1.38*10**-23*T\n",
+    "r=Eb/No           #Bit error probability is\n",
+    "Pbe=0.5*erfc(sqrt(r/2))*10**5\n",
+    "Pbe=round(Pbe,1)\n",
+    "print 'The bit error probability',Pbe,'*10**-5' "
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 12.9.1,Pg.no.435"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 33,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a)The bit error probability 0.00078\n",
+      "b)The bit error probability 0.00337\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import exp\n",
+    "ENR=10.0   #energy to noise density ratio\n",
+    "Pbe1=0.5* erfc(sqrt(ENR/2))\n",
+    "Pbe1=round(Pbe1,5)\n",
+    "print 'a)The bit error probability',Pbe1\n",
+    "Pbe2=(0.5)*exp(-(ENR/2))\n",
+    "Pbe2=round(Pbe2,5)\n",
+    "print 'b)The bit error probability',Pbe2"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 12.13.1,Pg.no.451"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 24,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The probability of a received codeword 5.33 *10**5\n",
+      "P_in= 5.6 *10**5\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "Pbec=0.01\n",
+    "n=8.0\n",
+    "i=3.0\n",
+    "Pi=(Pbec**i)*((1-(Pbec))**(n-i))\n",
+    "Cin=(math.factorial(n))/(math.factorial(i)*math.factorial(n-i))\n",
+    "Pin=Cin*Pi*10**5\n",
+    "P_in=Cin*Pbec**i*10**5\n",
+    "Pin=round(Pin,2)\n",
+    "P_in=round(P_in,2)\n",
+    "print 'The probability of a received codeword',Pin,'*10**5'\n",
+    "print 'P_in=',P_in,'*10**5'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 12.13.3,Pg.no.454"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 22,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a)The bit error probability 0.079\n",
+      "b)The bit error probability 2.25\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt,erf\n",
+    "SN_dB=9\n",
+    "SNR=10**(SN_dB/10)\n",
+    "PbeU=0.5 * (1-erf(sqrt(SNR)))\n",
+    "BERu=PbeU\n",
+    "BERu=round(BERu,3)\n",
+    "print 'a)The bit error probability',BERu\n",
+    "n=10\n",
+    "k=n-1\n",
+    "r=k/n\n",
+    "SNR1=r*SNR\n",
+    "PbeC=0.5 *(1-erf(sqrt(SNR1)))\n",
+    "BERc=(n-1)*PbeC**2\n",
+    "print 'b)The bit error probability',BERc"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 12.13.4,Pg.no.457"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 20,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a)The bit−error rate is 0.079\n",
+      "b)The new bit error rate is 3.5\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "SN_dB=8\n",
+    "SNR=10**(SN_dB/10) #a) Determination of bit error rate\n",
+    "PbeU=0.5*(1-erf(sqrt(SNR)))\n",
+    "BER_U=PbeU\n",
+    "BER_U=round(BER_U,3)\n",
+    "print 'a)The bit−error rate is',BER_U\n",
+    "#b)new bit error rate\n",
+    "n=15\n",
+    "k=11\n",
+    "t=1\n",
+    "r=k/n\n",
+    "SNR_n=r*SNR\n",
+    "PbeC=0.5*(1-erf(sqrt(SNR_n)))\n",
+    "BER_C=((math.factorial(n-1))*PbeC**(t+1))/((math.factorial(t)) *(math.factorial(n-t-1)))\n",
+    "print 'b)The new bit error rate is',BER_C "
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter13_Transmission_Lines_And_Cables.ipynb b/Electronic_Communication_by_D._Roddy/Chapter13_Transmission_Lines_And_Cables.ipynb
new file mode 100644
index 00000000..38e1d0d6
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter13_Transmission_Lines_And_Cables.ipynb
@@ -0,0 +1,290 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter13 Transmission Lines And Cables"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 13.5.2,Pg.no.475"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The attenuation coeff is 0.005 dB/m\n",
+      "The attenuation coeff is 8.04 dB/mile\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "a=0.0006  #The attenuation coeff in N/m\n",
+    "#a) Determinaion of the attenuation coeff in dB/m\n",
+    "a_dB=8.686*a\n",
+    "a_dB=round(a_dB,3)\n",
+    "print 'The attenuation coeff is',a_dB,'dB/m'\n",
+    "#b) Determination of attenuation coeff in dB/mile\n",
+    "k=1609   #conversion coeff for meter to mile\n",
+    "a_dB_mile=k*a_dB\n",
+    "a_dB_mile=round(a_dB_mile,2)\n",
+    "print 'The attenuation coeff is',a_dB_mile,'dB/mile'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 13.10.1,Pg.no.485"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 33,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a)The equivalent series resistance is 37.15 ohm\n",
+      "  The equivalent series reactance is 27.63 ohm\n",
+      "b)The equivalent parallel resistance is 57.7 ohm\n",
+      "  The equivalent parallel reactance is -77.57 ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "Z0=50.0   #measured in ohm\n",
+    "VSWR=2.0\n",
+    "d=0.2     #distance from load to firstt minimum\n",
+    "T=(VSWR -1)/(VSWR+1)\n",
+    "pi=180.0\n",
+    "Ql=pi*(4*0.2-1)       #using Euler’s identity\n",
+    "e=complex(math.cos(Ql),math.sin(Ql))   #expansion for e ˆ( jQl )\n",
+    "a=T*e  \n",
+    "#Load impedance is given as\n",
+    "ZL=Z0*(1+a)/(1-a)\n",
+    "Zlr=round(ZL.real,2)\n",
+    "Zli=round(ZL.imag,2)\n",
+    "print 'a)The equivalent series resistance is',Zlr,'ohm'\n",
+    "print '  The equivalent series reactance is',Zli,'ohm'\n",
+    "Yl=1/ZL\n",
+    "Yl1=round(1/Yl.real,2)\n",
+    "Yli=round(1/Yl.imag,2)\n",
+    "print 'b)The equivalent parallel resistance is',Yl1,'ohm'\n",
+    "print '  The equivalent parallel reactance is',Yli,'ohm'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 13.11.1,Pg.no.488"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 34,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The equivalent inductive reactance is 36.33 j ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "d=0.1   #length of 50ohm short−circuited line\n",
+    "Z0=50   #in ohm\n",
+    "f=500*10**6   #freq in Hz\n",
+    "Bl=2*pi*d \n",
+    "#a) Determination of equivalent inductive reactance\n",
+    "Z=complex(0,Z0*math.tan(Bl))\n",
+    "Z=round(Z.imag,2)\n",
+    "print 'The equivalent inductive reactance is',Z,'j','ohm'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 13.17.1,Pg.no.513"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 35,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a) The equivalent series resistance is 46.93 ohm\n",
+      "   The equivalent series reactance is 17.24 ohm\n",
+      "b) The equivalent parallel resistance is 53.27 ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "VSWR=2.0\n",
+    "l_min=0.2\n",
+    "Z0=50.0\n",
+    "Ql=((4*l_min )-1)*pi\n",
+    "tl=(VSWR -1)/(VSWR+1)\n",
+    "Tl=complex(0,tl*math.e**(Ql))\n",
+    "Zl=Z0*(1+Tl)/(1-Tl)\n",
+    "Zr=round(Zl.real,2)\n",
+    "Zm=round(Zl.imag,2)\n",
+    "print 'a) The equivalent series resistance is',Zr,'ohm' \n",
+    "print '   The equivalent series reactance is',Zm,'ohm'\n",
+    "Yl=1/Zl\n",
+    "Yl=1/Yl.real\n",
+    "Yl=round(Yl,2)\n",
+    "print 'b) The equivalent parallel resistance is',Yl,'ohm'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 13.17.2,Pg.no.514"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 20,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The input impedance is 50.0 + -2.87e-05 j ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "ZL=complex(30,0)-complex(0,23)\n",
+    "l=0.5     #length of line in m\n",
+    "Z0=50.0     #characteristic impedance in ohm\n",
+    "wl=0.45   #wavelength on the line in m\n",
+    "B=2*pi/wl\n",
+    "Tl=(ZL-Z0)/(ZL+Z0)\n",
+    "VI=1.0     #reference voltage in volt\n",
+    "VR=VI*Tl\n",
+    "z=complex(B*l)\n",
+    "Vi=VI*math.e**(z)\n",
+    "Vr=VR*math.e**(-z)\n",
+    "V=Vi+Vr\n",
+    "I=(Vi-Vr)/Z0\n",
+    "Z=V/I\n",
+    "Z1=round(Z.real,2)\n",
+    "Zi=Z.imag*10**5\n",
+    "Zi=round(Zi,2)*10**-5\n",
+    "print 'The input impedance is',Z1,'+',Zi,'j','ohm'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 13.17.3,Pg.no.515"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 24,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The input impedance is (73+0j) ohm\n",
+      "The VSWR is 0.12 + 0.0 j\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi,sqrt\n",
+    "Z0=600.0\n",
+    "Zl=73.0  #in ohm\n",
+    "F=0.9\n",
+    "QF=(2*pi*F)/4 \n",
+    "#For matching , the effective load impedance on the main line must equal the characteristic impedance of the mail line\n",
+    "Zl1=Zl\n",
+    "Z01=sqrt(Zl1*Zl)\n",
+    "Tl=(Zl-Z01)/(Zl+Z01)\n",
+    "VI=1  #reference voltage\n",
+    "Vi=VI*math.e**(complex(0,QF));\n",
+    "Vr=Tl*VI*math.e**-(complex(0,QF))\n",
+    "V_in=Vi+Vr\n",
+    "I_in=(Vi-Vr)/Z01\n",
+    "Z_in=V_in/I_in\n",
+    "print'The input impedance is',Z_in,'ohm'\n",
+    "#the voltage reflection coeff is\n",
+    "TL_F=(Z_in -Z0)/(Z_in+Z0)\n",
+    "#the VSWr is given as\n",
+    "VSWR_F=(1+TL_F)/(1-TL_F)\n",
+    "VSWR_Fr=round(VSWR_F.real,2)\n",
+    "VSWR_Fi=VSWR_F.imag\n",
+    "print 'The VSWR is',VSWR_Fr,'+',VSWR_Fi,'j'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter14_WaveGuides.ipynb b/Electronic_Communication_by_D._Roddy/Chapter14_WaveGuides.ipynb
new file mode 100644
index 00000000..2010222d
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter14_WaveGuides.ipynb
@@ -0,0 +1,78 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter14 WaveGuides"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 14.2.1,Pg.no.524"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "i)TE10 wave will propogate because (wl_c >wl)\n",
+      "Guide wavelength is 3.98 cm\n",
+      "Phase velocity is 39800.0 *10**6 m/s\n",
+      "Group velocity is 2261306.53 m/s\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "a=2.286           #in cm\n",
+    "wl_c=2.0*a*10**-2   #in m\n",
+    "c=3.0*10**8\n",
+    "wl=c/10**10       #in m\n",
+    "print 'i)TE10 wave will propogate because (wl_c >wl)'\n",
+    "#determination of gide wl\n",
+    "wl_g=10**2*(wl/(sqrt(1-(wl/wl_c)**2.0)))\n",
+    "wl_g=round(wl_g,2)\n",
+    "print 'Guide wavelength is',wl_g,'cm'\n",
+    "#determination of phase velocity\n",
+    "vp=c*wl_g/wl*10**-6\n",
+    "print 'Phase velocity is',vp,'*10**6 m/s' \n",
+    "#determination of group velocity\n",
+    "vg=c*wl/wl_g\n",
+    "vg=round(vg,2)\n",
+    "print 'Group velocity is',vg,'m/s'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter15_Radio_Wave_Propogation.ipynb b/Electronic_Communication_by_D._Roddy/Chapter15_Radio_Wave_Propogation.ipynb
new file mode 100644
index 00000000..3cb6638e
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter15_Radio_Wave_Propogation.ipynb
@@ -0,0 +1,277 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter15 Radio Wave Propogation"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 15.2.1,Pg.no.538"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The free−space transmission loss is 195.67\n",
+      "The received power 5.42e-12 watts\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "ht=36000   #height of satellite in km\n",
+    "f=4000     #freq used in MHz\n",
+    "Gt=15.0    #transmitting antenna gain\n",
+    "Gr=45.0    #receiving antenna gain\n",
+    "#A) Determination of free−space transmission loss\n",
+    "L=32.5+20*math.log10(ht)+20*math.log10(f)\n",
+    "L=round(L,2)\n",
+    "print 'The free−space transmission loss is',L\n",
+    "#B) Determination of received power Pr\n",
+    "Pt=200.0    #transmitted power in watt\n",
+    "Pr_Pt=Gt+Gr-L    #power ration in dB\n",
+    "Pr_Pt_watt=10**(Pr_Pt/10)    #power ratio in watts\n",
+    "#Therefore \n",
+    "Pr=Pt*Pr_Pt_watt*10**12\n",
+    "Pr=round(Pr,2)*10**-12\n",
+    "print 'The received power',Pr,'watts'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 15.2.2,Pg.no.539"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The open−ckt voltage induced is 282.42 uV\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi,sqrt\n",
+    "Pr=10.0   #radiated power in watt\n",
+    "f=150.0   #freq used in MHz\n",
+    "d2=50.0   #distance of dipole in km\n",
+    "#Therefore open−ckt voltage induced is given as\n",
+    "Vs=sqrt(30*Pr*1.64)/(d2*10**3)*2/pi\n",
+    "Vs=Vs*10**6\n",
+    "Vs=round(Vs,2)\n",
+    "print 'The open−ckt voltage induced is',Vs,'uV'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 15.3.1,Pg.no.545"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Field strength at a receiving antenna is 11.02 uV/m\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "Pt=100    #transmitted power\n",
+    "f=150     #freq used in MHz\n",
+    "d1=20     #height of transmitting antenna in m\n",
+    "Gt=1.64   #transmitting antenna gain\n",
+    "ht=2      #height of receiving antenna in m\n",
+    "d2=40     #distance in km\n",
+    "c=3*10**8\n",
+    "wl=c/(f*10**6)\n",
+    "E0=sqrt(30*Pt*Gt)   #Field strength at a receiving antenna is\n",
+    "ER=(E0*4*pi*d1*ht)/(wl*(d2*10**3)**2)\n",
+    "ER=ER*10**6\n",
+    "ER=round(ER,2)\n",
+    "print 'Field strength at a receiving antenna is',ER,'uV/m'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 15.3.2,Pg.no.548"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The maximum range is 25.1 miles\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "ht1=100\n",
+    "ht2=60    #antenna heights in ft\n",
+    "dmax_miles=sqrt(2*ht1)+sqrt(2*ht2)\n",
+    "dmax_miles=round(dmax_miles,2)\n",
+    "print 'The maximum range is',dmax_miles,'miles' "
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 15.4.1,Pg.no.560"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "d= 178.8 km\n",
+      "d= 10382.4 km\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "ht=200   #virtual height in km\n",
+    "a=6370   #in km\n",
+    "B_degree=20\n",
+    "B_rad=20*pi/180   #angle of elevation in degree\n",
+    "#The flat−earth approximation gives\n",
+    "d=2*ht/math.tan(B_degree)\n",
+    "d=round(d,1)\n",
+    "print 'd=',d,'km'\n",
+    "#By using radian measures for all angles\n",
+    "d=2*a*(((pi/2)-B_rad)-(math.asin(a*math.cos(B_degree)/(a+ht) )))\n",
+    "d=round(d,1)\n",
+    "print 'd=',d,'km'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 15.7.1,Pg.no.574"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The attenuation coeff is 0.04 N/m\n",
+      "The attenuation coeff in dB/m is 0.347 dB/m\n",
+      "The attenuation coeff is 4.0 N/m\n",
+      "The attenuation coeff in dB/m is 34.7 dB/m\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi,sqrt\n",
+    "conductivity = 4    #measured in S/m\n",
+    "rel_permittivity =80\n",
+    "u=4*pi*10**-7\n",
+    "f1=100              #measured in Hz\n",
+    "f2=10**6            #measured in Hz\n",
+    "#A)first it is necessary to evaluate the ratio of conductivity /w*rel permittivity\n",
+    "w1=2*pi*f1\n",
+    "r=conductivity/w1*rel_permittivity\n",
+    "#Therefore we have to use following eq to calculate the attenuation coeff as\n",
+    "a=sqrt(w1*conductivity*u/2)\n",
+    "a=round(a,3)\n",
+    "print 'The attenuation coeff is',a,'N/m'\n",
+    "#By using the conversion factor N=8.686 dB\n",
+    "a_dB=a*8.686\n",
+    "a_dB=round(a_dB,3)\n",
+    "print 'The attenuation coeff in dB/m is',a_dB,'dB/m'\n",
+    "w2=2*pi*f2\n",
+    "r=conductivity/w2*rel_permittivity\n",
+    "a=sqrt(w2*conductivity*u/2)\n",
+    "a=round(a,1)\n",
+    "print 'The attenuation coeff is',a,'N/m'\n",
+    "#By using the conversion factor 1N=8.686 dB\n",
+    "a_dB=a*8.686\n",
+    "a_dB=round(a_dB,1)\n",
+    "print 'The attenuation coeff in dB/m is',a_dB,'dB/m'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter16_Antennas.ipynb b/Electronic_Communication_by_D._Roddy/Chapter16_Antennas.ipynb
new file mode 100644
index 00000000..9718189b
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter16_Antennas.ipynb
@@ -0,0 +1,150 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter16 Antennas"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 16.7.2,Pg.no.590"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The −3dB beamwidth is 90.0 degree\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "g_x=0.5\n",
+    "x=math.asin(sqrt(g_x))\n",
+    "g_y=0.5\n",
+    "y1=math.asin(sqrt(g_y))\n",
+    "y=y1+90\n",
+    "#Therefore\n",
+    "z=y-x\n",
+    "print 'The −3dB beamwidth is',z,'degree'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 16.9.1,Pg.no.597"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "l_effective= 0.32\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "Io=1\n",
+    "wl=1\n",
+    "phy_length=wl/2\n",
+    "I_av=2*Io/pi\n",
+    "#Thus area is given as\n",
+    "Area=I_av*phy_length\n",
+    "l_eff=wl/pi\n",
+    "l_eff=round(l_eff,2)\n",
+    "#From the above eq l_effective is given as\n",
+    "print 'l_effective=',l_eff"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 16.19.1,Pg.no.621"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Effective area is 18.38 m**2\n",
+      "The directivity is 256633.2\n",
+      "The −3dB beamwidth is 0.35 degree\n",
+      "The null beamwidth is 0.7 degree\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "D=6.0        #reflector diameter in m\n",
+    "n=0.65     #illumination effeciency\n",
+    "f=10**10   #frequency of operation in Hz\n",
+    "c=3*10**8  #velo of light in m/s\n",
+    "wl=0.03  #c/f\n",
+    "A=(pi*D**2)/4\n",
+    "A_eff=n*A\n",
+    "A_eff=round(A_eff,2)\n",
+    "print 'Effective area is',A_eff,'m**2'\n",
+    "D0=(4*pi*A_eff)/wl**2\n",
+    "D0=round(D0,1)\n",
+    "print 'The directivity is',D0\n",
+    "BW_dB=70*wl/D\n",
+    "print 'The −3dB beamwidth is',BW_dB,'degree'\n",
+    "BW_null=2*BW_dB\n",
+    "print 'The null beamwidth is',BW_null,'degree' "
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter17_Telephone_Systems.ipynb b/Electronic_Communication_by_D._Roddy/Chapter17_Telephone_Systems.ipynb
new file mode 100644
index 00000000..b2ca6c1b
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter17_Telephone_Systems.ipynb
@@ -0,0 +1,82 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter17 Telephone Systems"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 17.1.1,Pg.no.641"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a)The max gain is 44.0 dB\n",
+      "b)The max gain is 30 dB\n",
+      "c)The amplr gain is 27.0 dB\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "FTL=50\n",
+    "M=12\n",
+    "NFL=2*FTL\n",
+    "NFLG=(NFL-M)\n",
+    "G_max1=NFLG/2\n",
+    "G_max1=round(G_max1,1)\n",
+    "print 'a)The max gain is',G_max1,'dB' \n",
+    "#b) Determination of max gain2 \n",
+    "IL=3\n",
+    "RLW=20\n",
+    "RLE=40\n",
+    "NL=(4*IL)+RLW+RLE\n",
+    "NLG=(NL-M)\n",
+    "G_max2=NLG/2\n",
+    "print 'b)The max gain is',G_max2,'dB' \n",
+    "#c ) Determination of amplr gain\n",
+    "LT=15.0\n",
+    "OM=6.0\n",
+    "OLW=(RLW-LT)/2\n",
+    "OLE=(RLE-LT)/2\n",
+    "A=OM+OLW+OLE+(2*IL)\n",
+    "print 'c)The amplr gain is',A,'dB'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter18_Fascimile_and_Television.ipynb b/Electronic_Communication_by_D._Roddy/Chapter18_Fascimile_and_Television.ipynb
new file mode 100644
index 00000000..ed4c9ac9
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter18_Fascimile_and_Television.ipynb
@@ -0,0 +1,307 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter18 Fascimile and Television"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 18.2.1,Pg.no.671"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The index of co−operation is 1105.84\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "#given\n",
+    "D=70.4\n",
+    "P=0.2   \n",
+    "#Determination of index of co−operation\n",
+    "IOC_CCITT=D/P\n",
+    "IOC_IEEE=IOC_CCITT*(pi)\n",
+    "IOC_IEEE=round(IOC_IEEE,2)\n",
+    "print 'The index of co−operation is',IOC_IEEE"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 18.2.2,Pg.no.676"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The no . of pixels in scan line is 826.0 pixels/line \n",
+      "The scan rate is 2 lines/sec \n",
+      "The pixel rate is 1652.0 pixels/sec\n",
+      "The document Transmission time is 8 sec\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "D=68.4\n",
+    "P=0.26\n",
+    "rpm=120\n",
+    "n=1075\n",
+    "#Determination of no . of pixels scan\n",
+    "Npx=(pi)*(D/P)\n",
+    "Npx=round(Npx,0)\n",
+    "print 'The no . of pixels in scan line is',Npx,'pixels/line ' \n",
+    "#Determination of scan rate\n",
+    "Rs=rpm/60\n",
+    "print 'The scan rate is',Rs,'lines/sec '\n",
+    "#Determination of pixel rate is\n",
+    "Rpx=Npx*Rs\n",
+    "Rpx=round(Rpx,0)\n",
+    "print 'The pixel rate is',Rpx,'pixels/sec'\n",
+    "f_max=Rpx/2\n",
+    "#Determination of document Tx time\n",
+    "td=n/(60*Rs)\n",
+    "print 'The document Transmission time is',td,'sec'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 18.3.1,Pg.no.693"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The no . of pixel periods in line period is 485 lines\n",
+      "The picture height is 485 pixels\n",
+      "The picture length is 580.8 pixels\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "a=(4/3)          #aspect ratio\n",
+    "N=525            #no . of line periods per frame\n",
+    "Ns=40            #no . of suppressed lines\n",
+    "#Determination of no . of pixel periods in line period\n",
+    "Nv=N-Ns\n",
+    "print 'The no . of pixel periods in line period is',Nv,'lines'\n",
+    "#Determination of picture height and width\n",
+    "Nh=a*Nv\n",
+    "print 'The picture height is',Nh,'pixels'\n",
+    "Nl=(Nh/0.835)\n",
+    "Nl=round(Nl,1)\n",
+    "print 'The picture length is',Nl,'pixels'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 18.3.2,Pg.no.694"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The horizontal frequency is 15750.0 Hz\n",
+      "The vertical frequency is 60.0 Hz\n",
+      "The time required to scan one line is 6.35e-05 sec\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "N=525.0\n",
+    "P=30.0\n",
+    "#Determination of horizontal and vertical synchhronization freq .\n",
+    "fh=N*P\n",
+    "print 'The horizontal frequency is',fh,'Hz'\n",
+    "fv=2*P\n",
+    "print 'The vertical frequency is',fv,'Hz'\n",
+    "#Determination of time reqd to scan one line\n",
+    "Th=((fh)**-1)*10**5\n",
+    "Th=round(Th,2)*10**-5\n",
+    "print 'The time required to scan one line is',Th,'sec'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 18.3.3,Pg.no.695"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "the band width is 4272187.5 Hz\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "fh=15750\n",
+    "Nl=775\n",
+    "#Determination of video bandwidth\n",
+    "Bv=0.35*fh*Nl\n",
+    "Bv=round(Bv,1)\n",
+    "print 'the band width is',Bv,'Hz'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 18.7.1,Pg.no.706"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The viewing angle is 10.78 degrees\n",
+      "The min.viewing dist is -0.14 m\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "a=4/3                #aspect ratio\n",
+    "D=48.26*10**-2       #CRT tube diagonal\n",
+    "Nh=647.0\n",
+    "H=sqrt((a**2)*(D**2)/(1+a**2))\n",
+    "#Determination of viewing angle & minimum distance\n",
+    "w=H/Nh\n",
+    "theta=Nh*(1/60.0)     #As each pixel subtend 1 minute of arc\n",
+    "theta=round(theta,2)\n",
+    "print 'The viewing angle is',theta,'degrees' \n",
+    "X=H/(2*math.tan(theta/2))\n",
+    "X=round(X,2)\n",
+    "print 'The min.viewing dist is',X,'m'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 18.7.2,Pg.no.707"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The viewing angle is 30.67 degrees\n",
+      "The viewing dist is -1.27 m\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "a=16/9\n",
+    "D=1.40\n",
+    "Nh=1840.0         #Assuming square pixel\n",
+    "H=sqrt((a**2)*(D**2)/(1+a**2))\n",
+    "#Determination of viewing angle\n",
+    "theta=Nh*(1/60.0)\n",
+    "theta=round(theta,2)\n",
+    "print 'The viewing angle is',theta,'degrees'\n",
+    "#Determination of viewing dist\n",
+    "X=H/(2*math.tan(theta/2));\n",
+    "X=round(X,2)\n",
+    "print 'The viewing dist is',X,'m'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter19_Satellite_Communications.ipynb b/Electronic_Communication_by_D._Roddy/Chapter19_Satellite_Communications.ipynb
new file mode 100644
index 00000000..178a9c6c
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter19_Satellite_Communications.ipynb
@@ -0,0 +1,184 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter19 Satellite Communications"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 19.14.1,Pg.no.737"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The carrier to noise ratio in dB is 93.88\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "P_HPA=600.0\n",
+    "TFL_dB=1.5\n",
+    "G_dB_ES=50.0\n",
+    "RFL_dB=1\n",
+    "GTR_dB_SAT =-8\n",
+    "FSL_dB=200\n",
+    "AML_dB=0.5\n",
+    "PL_dB=0.5\n",
+    "AA_dB=1\n",
+    "#Determination of carrier to noise ratio\n",
+    "P_dB_HPA=10*math.log10(P_HPA/1)\n",
+    "EIRP_dB=P_dB_HPA -TFL_dB+G_dB_ES\n",
+    "TPL_dB=FSL_dB+AML_dB+PL_dB+AA_dB\n",
+    "CNoR_dB=EIRP_dB -TPL_dB -RFL_dB+GTR_dB_SAT+228.6\n",
+    "CNoR_dB=round(CNoR_dB,2)\n",
+    "print 'The carrier to noise ratio in dB is',CNoR_dB"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 19.14.2,Pg.no.739"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The carrier to noise ratio is 78.23\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "f=14*10**9\n",
+    "BO_dB=10\n",
+    "GTR_dB_SAT=3\n",
+    "RFL_dB=1\n",
+    "phi_dB=-98\n",
+    "c=3*10**8\n",
+    "#Determination of carrier to noise ratio\n",
+    "wav=c/f\n",
+    "x=0.00003654067   #x=((wav**2)/(4*pi))\n",
+    "Ao_dB=10*math.log10(x)\n",
+    "CNo_dB=phi_dB -BO_dB+GTR_dB_SAT -RFL_dB+Ao_dB+228.6\n",
+    "CNo_dB=round(CNo_dB,2)\n",
+    "print 'The carrier to noise ratio is',CNo_dB"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 19.16.1,Pg.no.741"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The overall carrier to noise ratio is 79.59\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "CNo_dB_U=88\n",
+    "CNo_dB_D=78\n",
+    "NoC_U=10**(-CNo_dB_U/10)\n",
+    "NoC_D=10**(-CNo_dB_D/10)\n",
+    "NoC=NoC_U+NoC_D\n",
+    "CNo_dB=10*math.log10(1/NoC)\n",
+    "CNo_dB=round(CNo_dB,2)\n",
+    "print 'The overall carrier to noise ratio is',CNo_dB"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 19.17.1,Pg.no.742"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The ratio C/No is 71.49\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "Eb_N0=9.6           #ratio expessed in dB\n",
+    "Rb=1.544*10**6      #bit rate expessed in bps\n",
+    "#The bit rate in dB relative to 1bps is\n",
+    "R_dB_b=10*math.log10(Rb)\n",
+    "#The required CN0 ratio is\n",
+    "CNo_db=Eb_N0+R_dB_b\n",
+    "CNo_db=round(CNo_db,2)\n",
+    "print 'The ratio C/No is',CNo_db "
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter1_Passive_Circuits.ipynb b/Electronic_Communication_by_D._Roddy/Chapter1_Passive_Circuits.ipynb
new file mode 100644
index 00000000..7e165345
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter1_Passive_Circuits.ipynb
@@ -0,0 +1,372 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter 1 Passive Circuits"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 1.2.2, Pg.no.5"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 50,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of resistance R is 16.61 ohm\n",
+      "The value of resistance R3 is 66.8 ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "Ro=50.0\n",
+    "ILdB=6.0                    #T−type attenuator provide 6−dB insertion loss \n",
+    "#calculation\n",
+    "IL=10**-(ILdB/20)           #Determination of R\n",
+    "R=Ro*(1-IL)/(1+IL)\n",
+    "R=round(R,2)\n",
+    "print 'The value of resistance R is',R,'ohm' \n",
+    "#Determination of R3\n",
+    "R3=(2*Ro*IL)/(1-(0.5)**2)\n",
+    "R3=round(R3,1)\n",
+    "print 'The value of resistance R3 is',R3,'ohm'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 1.2.3,Pg.no.6"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 51,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of resistance RA and RB is 150.5 ohm\n",
+      "The value of resistance RC is 37.4 ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "Ro=50.0\n",
+    "ILdB=6.0\n",
+    "IL=10**-(ILdB/20)         #Determination of RA and RB\n",
+    "RA=Ro*(1+IL)/(1-IL)\n",
+    "RA=round(RA,1)\n",
+    "print 'The value of resistance RA and RB is',RA,'ohm'\n",
+    "#Determination of RC\n",
+    "RC=Ro*(1-(IL)**2)/(2*IL)\n",
+    "RC=round(RC,1)\n",
+    "print 'The value of resistance RC is',RC,'ohm'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 1.2.4,Pg.no.8"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 52,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of resistance R1 is 43.3 ohm\n",
+      "The value of resistance R3 is 86.61 ohm\n",
+      "The value of insertion loss is 5.42 dB\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import log10,sqrt\n",
+    "#given\n",
+    "Rs=75.0          #resistance\n",
+    "Rl=50.0       \n",
+    "#Determination of R1\n",
+    "R1=sqrt(Rs*(Rs-Rl))\n",
+    "R1=round(R1,2)\n",
+    "print 'The value of resistance R1 is',R1,'ohm'\n",
+    "#Determination of R3\n",
+    "R3=((Rs**2)-(R1**2))/R1\n",
+    "R3=round(R3,2)\n",
+    "print 'The value of resistance R3 is',R3,'ohm'\n",
+    "#Determination of insertion loss\n",
+    "IL=(R3*(Rs+R1))/((Rs+R1+R3)*(R3+R1)-(R3)**2)\n",
+    "ILdB=-20*log10(IL) #convertion of power in decibels\n",
+    "ILdB=round(ILdB,2)\n",
+    "print 'The value of insertion loss is',ILdB,'dB'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 1.2.5,Pg.no.9"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 53,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of resistance R2 is 44.721 ohm\n",
+      "The value of resistance R3 is 11.18 ohm\n",
+      "The value of insertion loss is 9.99 dB\n"
+     ]
+    }
+   ],
+   "source": [
+    "from math import log10,sqrt\n",
+    "Rs=10.0\n",
+    "Rl=50.0        #Determination of R2\n",
+    "R2=sqrt(Rl*(Rl-Rs))\n",
+    "R2=round(R2,3)\n",
+    "print 'The value of resistance R2 is',R2,'ohm'\n",
+    "#Determination of R3\n",
+    "R3=((Rl**2)-(R2**2))/R2\n",
+    "R3=round(R3,2)\n",
+    "print 'The value of resistance R3 is',R3,'ohm'\n",
+    "#Determination of insertion loss\n",
+    "IL=(R3*(Rs+Rl))/((Rs+R3)*(R3+R2+Rl)-(R3)**2)\n",
+    "ILdB=-20*log10(IL)           #convertion of power in decibels\n",
+    "ILdB=round(ILdB,2)\n",
+    "print 'The value of insertion loss is',ILdB,'dB'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 1.5.1,Pg.no.19"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 54,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of self resonant freq is 60.2 MHz\n",
+      "The value of Q−factor is 31.4\n",
+      "The value of effective inductance is 1.0 uH\n",
+      "The value of effective Q−factor is 26.0\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "C=7*10**-12\n",
+    "R=5.0\n",
+    "L=10**-6\n",
+    "f=25*10**6       \n",
+    "#Determination of self resonant freq of coil denoted as Fsr\n",
+    "Fsr=1/(2*3.14*(L*C)**0.5)\n",
+    "Fsr=Fsr/(10**6)\n",
+    "Fsr=round(Fsr,1)\n",
+    "print 'The value of self resonant freq is',Fsr,'MHz'\n",
+    "#Determination of Q−factor of coil , excluding self − capacitive effects\n",
+    "Q=(2*3.14*f*L)/R\n",
+    "print 'The value of Q−factor is',Q\n",
+    "#Determination of effective inductance\n",
+    "Leff=(1-(25/60)**2)**-1\n",
+    "Leff=round(Leff,0)\n",
+    "print 'The value of effective inductance is',Leff,'uH'\n",
+    "#Determination of effective Q−factor\n",
+    "Qeff=(1-0.173)*Q\n",
+    "Qeff=round(Qeff,0)\n",
+    "print 'The value of effective Q−factor is',Qeff"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 1.8.1,Pg.no.23"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 55,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of common resonant freq is 3.77 Mrad/sec\n",
+      "Zm= 5.655j\n",
+      "The transfer impedance is (43.8+2250j) ohm\n"
+     ]
+    }
+   ],
+   "source": [
+    "import cmath\n",
+    "from math import sqrt\n",
+    "#given\n",
+    "Lp=150*10**-6           #inductance\n",
+    "Ls=150*10**-6\n",
+    "Cp=470*10**-12          #capacitance\n",
+    "Cs=470*10**-12          #Lp=Ls=150 uH,Cp=Cs=470 pF\n",
+    "Q=85.0                  #Q−factor for each ckt is 85\n",
+    "c=0.01                  #Coeff of coupling is 0.01\n",
+    "Rl=5000.0               #Load resistance Rl=5000 ohm\n",
+    "r=75000.0               #Constant current source with internal resistance r=75 kohm\n",
+    "#calculations\n",
+    "#Determination of common resonant frequency\n",
+    "wo=1/(sqrt(Lp*Cp))\n",
+    "wo=wo/(10**6)\n",
+    "wo=round(wo,2)\n",
+    "print 'The value of common resonant freq is',wo,'Mrad/sec'\n",
+    "p=3.77*10**6\n",
+    "Z2=complex(62.9004,558)               #Formula=Rl/(1+(p*j*Cs*Rl))\n",
+    "Z1=complex(4.3,565)                   #Formula=r/(1+(p*j*Cp*r)) ;At resonance Zs=Zp=Z\n",
+    "z=complex(0,1)\n",
+    "Z=wo*Ls*(1/Q +z)\n",
+    "Zm=complex(0,p*c*Lp)             #Determination of denominator\n",
+    "print 'Zm=',Zm\n",
+    "Dr=((Z+Z1)*(Z+Z2))-(Zm**2) \n",
+    "Dr=complex(791,80)\n",
+    "#Hence transfer impedance is given as\n",
+    "Zr=complex(43.8,2.25*10**3)        #formula=(Z1*Z2*Zm)/Dr\n",
+    "print 'The transfer impedance is',Zr,'ohm'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 1.10.1,Pg.no.31"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 56,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of common resonant freq is 169.56 Mrad/ sec\n",
+      "The value of Gl is 5.0 mSec\n",
+      "The value of alpha is 3.14\n",
+      "The value of effective load is 1.97 kohm\n",
+      "The value of tuning capacitance is 47.73 pF\n",
+      "The value of Rd is 18.534 kohm\n",
+      "The value of −3dB BW is 1.69 MHz\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "C1=70*10**-12\n",
+    "C2=150*10**-12\n",
+    "Rl=200.0\n",
+    "Q=150.0\n",
+    "f=27*10**6\n",
+    "r=40000.0\n",
+    "#Determination of common resonant freq\n",
+    "wo=2*3.14*f\n",
+    "wo=wo/(10**6)\n",
+    "print 'The value of common resonant freq is',wo,'Mrad/ sec'\n",
+    "#Determination of Gl\n",
+    "Gl=1/Rl\n",
+    "G1=Gl*(10**3) \n",
+    "print'The value of Gl is',G1,'mSec'\n",
+    "#Checking the approxiamtion in denominator\n",
+    "ap=((wo*(C1+C2))/(Gl))**2\n",
+    "alpha=(C1+C2)/C1\n",
+    "alpha=round(alpha,2)\n",
+    "print 'The value of alpha is',alpha\n",
+    "#Determination of effective load\n",
+    "Reff=((alpha)**2)*Rl\n",
+    "Reff=Reff/(10**3)\n",
+    "Reff=round(Reff,2)\n",
+    "print 'The value of effective load is',Reff,'kohm'   \n",
+    "#If effective load is much less than internal resistance hence tuning capacitance then\n",
+    "Cs=C1*C2/(C1+C2)\n",
+    "Cs=Cs*(10**12)\n",
+    "Cs=round(Cs,2)\n",
+    "print 'The value of tuning capacitance is',Cs,'pF'\n",
+    "#Determination of Rd\n",
+    "Rd=Q/(wo*Cs)*(10**3)\n",
+    "Rd=round(Rd,3)\n",
+    "print 'The value of Rd is',Rd,'kohm'\n",
+    "#If Rd is much greater than Reff then −3dB bandwidth is given by\n",
+    "B=1/(2*3.14*C2*alpha*Rl)\n",
+    "B=B/(10**6)\n",
+    "B=round(B,2)\n",
+    "print 'The value of −3dB BW is',B,'MHz'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter20_Fibre_Optic_Communication.ipynb b/Electronic_Communication_by_D._Roddy/Chapter20_Fibre_Optic_Communication.ipynb
new file mode 100644
index 00000000..254e70df
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter20_Fibre_Optic_Communication.ipynb
@@ -0,0 +1,587 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter20 Fibre Optic Communication"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.2.1,Pg.no.753"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The numerical aperture is 0.35\n",
+      "The acceptance angle is 0.36\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "n1=1.55  #RI of glass\n",
+    "n2=1.51  #RI of clad\n",
+    "#NA of the fibe is given as\n",
+    "NA=n1*sqrt(2*(n1-n2)/n1)\n",
+    "NA=round(NA,2)\n",
+    "print 'The numerical aperture is',NA\n",
+    "#Acceptance angle is given as\n",
+    "acc_angle=math.asin(NA)\n",
+    "acc_angle=round(acc_angle,2)\n",
+    "print 'The acceptance angle is',acc_angle"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.2.2,Pg.no.761"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The V number is 69.12\n",
+      "the approximate no . of modes are 2388.8\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "d=50*10**-6\n",
+    "wav=0.8*10**-6\n",
+    "NA=0.352 \n",
+    "#Determination of V number\n",
+    "V=(pi)*d*NA/wav\n",
+    "V=round(V,2)\n",
+    "print 'The V number is',V\n",
+    "#Determination of approximate number of modes\n",
+    "N=(V**2)/2\n",
+    "N=round(N,1)\n",
+    "print 'the approximate no . of modes are',N"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.2.3,Pg.no.762"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The v number is 4.2291\n",
+      "From the table it is seen that 6 modes have cut off v less than 4.23\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "d=5*10**-6\n",
+    "wave=1.3*10**-6\n",
+    "NA=0.35\n",
+    "#Determination of V number\n",
+    "V=(pi)*d*NA/wave\n",
+    "V=round(V,4)\n",
+    "print 'The v number is',V\n",
+    "print 'From the table it is seen that 6 modes have cut off v less than 4.23'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.2.4,Pg.no.763"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 32,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "No . of modes supported by graded index fiber= 1195\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "a=2     #gradding profile index\n",
+    "V=69.1  #normalized cutoff frequency\n",
+    "N=2390  #number of modes supported as a step index fiber\n",
+    "#Determination of no . of modes supported by graded index fiber\n",
+    "N_a=(N*a)/(a+2)\n",
+    "print 'No . of modes supported by graded index fiber=',N_a"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.2.5,Pg.no.763"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 30,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a) the normilized index difference is 0.002\n",
+      "b) cladding index required is 1.55\n",
+      "The max acceptance angle is 0.1\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "d=10*10**-6\n",
+    "wav=1.3*10**-6\n",
+    "n1=1.55\n",
+    "V_max=2.405\n",
+    "NA=(V_max*wav)/(pi*d)\n",
+    "#a) Determination of maximum normailized index difference\n",
+    "del1=(0.5)*((NA/n1)**2)\n",
+    "del1=round(del1,3)\n",
+    "print 'a) the normilized index difference is',del1\n",
+    "#b) Determination of r effective index of claddin glass\n",
+    "n2=n1*(1-del1)\n",
+    "n2=round(n2,2)\n",
+    "print 'b) cladding index required is',n2\n",
+    "#Determination of the fiber acceptance angle\n",
+    "theta_max=math.asin(NA)\n",
+    "theta_max=round(theta_max,3)\n",
+    "print'The max acceptance angle is',theta_max"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.3.1,Pg.no.766"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 29,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a)The repeater dist for 0.9um wavelength is 12 km\n",
+      "b)The repeater dist for 1.5um wavelength is 83.33 km\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "A_max=25\n",
+    "A1=2\n",
+    "A2=0.3\n",
+    "#a) Determination of repeater dist at 0.9um wavelength\n",
+    "z1=A_max/A1\n",
+    "print 'a)The repeater dist for 0.9um wavelength is',z1,'km'\n",
+    "#b) Determination of repeater dist at 1.5um wavelength\n",
+    "z2=A_max/A2\n",
+    "z2=round(z2,2)\n",
+    "print 'b)The repeater dist for 1.5um wavelength is',z2,'km'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.4.1,Pg.no.772"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 28,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The intermodal dispersion is 1.37e-07 s/km\n",
+      "The intermodal dispertion for l=12.5 is 1.71e-09 s\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "n1=1.55\n",
+    "del1=0.0258\n",
+    "l=12.5\n",
+    "z=1000\n",
+    "c=3*10**8    #velocity of light\n",
+    "#a) Determination of intermodal dispersion\n",
+    "del_per_km=(n1*z*del1)/((1-del1)*c)*10**7\n",
+    "del_per_km=round(del_per_km,2)*10**-7\n",
+    "print 'The intermodal dispersion is',del_per_km ,'s/km'\n",
+    "#b) Determination of intermodal dispersion for l =12.5\n",
+    "del_l=del_per_km*l/1000*10**9\n",
+    "del_l=round(del_l,2)*10**-9\n",
+    "print 'The intermodal dispertion for l=12.5 is',del_l,'s'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.4.2,Pg.no.773"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 19,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The intermodal dispersion is 5.37e-05 sec\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "n1=1.55\n",
+    "del1=(258.0)*(10**-2)\n",
+    "z=1000\n",
+    "c=3*10**8\n",
+    "z_disp=12.5\n",
+    "del_graded=(n1*z*del1**2)/(8*c)\n",
+    "#Determination of intermodal dispersion\n",
+    "del_total=del_graded*z_disp*10**5\n",
+    "del_total=round(del_total,2)*10**-5\n",
+    "print 'The intermodal dispersion is',del_total,'sec'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.4.3,Pg.no.774"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 20,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The total material dispersion is -2.8125 ns\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "wav_0=0.8*10**-6\n",
+    "Dm=-0.15\n",
+    "wav_3=1.5\n",
+    "z=12.5\n",
+    "del_t=Dm*wav_3\n",
+    "#Determination of total material dispersion\n",
+    "del_md=del_t*z\n",
+    "print 'The total material dispersion is',del_md,'ns' "
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.4.4,Pg.no.775"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 21,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Expected waveguide dispersion is 495.0 ps\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "Dm=6.6\n",
+    "z=12.5\n",
+    "del_3=6\n",
+    "del_wg=Dm*z*del_3\n",
+    "print'Expected waveguide dispersion is',del_wg,'ps'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.4.5,Pg.no.776"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 27,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The total dispersion is 1.0 ns\n",
+      "The max allowed bit rate is 500.0 Mbps\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "del_imd=0\n",
+    "del_md=2.81\n",
+    "del_wgd=0.495\n",
+    "t_w=2.5\n",
+    "del_tot=((del_imd**2)+(del_md**2)+(del_wgd**2))**(1/2)\n",
+    "print 'The total dispersion is',del_tot,'ns'\n",
+    "t_r=((t_w**2)+(del_tot**2))**(1/2) \n",
+    "#Determination of max allowed bit rate\n",
+    "B=(1000/(2*t_r))\n",
+    "print 'The max allowed bit rate is',B,'Mbps'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.4.6,Pg.no.778"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 23,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a)The BW distance product for fiber is 0.125 Mbps−km\n",
+      "b)The disp limited length for a fiber is 12.5 km\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "del_t=4.0\n",
+    "B=10.0\n",
+    "#a) Determination of BW distance product\n",
+    "BDP=1/(2*del_t)\n",
+    "print'a)The BW distance product for fiber is',BDP,'Mbps−km'\n",
+    "#b) Determiation of dispersion limited length\n",
+    "z_max_disp=BDP/(B*10**-3)\n",
+    "print'b)The disp limited length for a fiber is',z_max_disp,'km'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.5.1,Pg.no.780"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 24,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a) i) the wavelength is 0.7 um\n",
+      "a) ii) the freq is 459307010.5 MHz\n",
+      "b) i) the wavelength is 0.85 um\n",
+      "b) ii) the freq is 352941176.471 MHz\n",
+      "c)i) the wavelength is 1.3 um\n",
+      "c)ii) the freq is 230620467.4 MHz\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "E1=1.9\n",
+    "E2=1.46\n",
+    "E3=0.954\n",
+    "eV=1.9       #All in eV\n",
+    "c=3*10**8    #speed of light\n",
+    "#a) Determination of wavelength and freq for E1=1.9\n",
+    "wav1=1.241/E1\n",
+    "f1=c/(wav1)\n",
+    "wav1=round(wav1,1)\n",
+    "f1=round(f1,1)\n",
+    "print 'a) i) the wavelength is',wav1,'um'\n",
+    "print 'a) ii) the freq is',f1,'MHz'\n",
+    "#b) Determination of wavelength and freq for E2=1.46\n",
+    "wav2=1.241/E2\n",
+    "f2=c/(wav2)\n",
+    "print 'b) i) the wavelength is',wav2,'um'\n",
+    "print 'b) ii) the freq is',f2,'MHz'\n",
+    "#c ) Determination of wavelength and freq for E3=0.945\n",
+    "wav3=1.241/E3\n",
+    "f3=c/(wav3)\n",
+    "wav3=round(wav3,1)\n",
+    "f3=round(f3,1)\n",
+    "print'c)i) the wavelength is',wav3,'um'\n",
+    "print'c)ii) the freq is',f3,'MHz'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 20.8.1,Pg.no.799"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 25,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a) the loss−limited fiber is 17.75 km\n",
+      "b) the max BW for loss−limited length is 0.022 Gbps\n",
+      "the dispertion limited length is 11.32 km\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "#given\n",
+    "pt=0\n",
+    "pr=-57\n",
+    "Nc=2\n",
+    "BER=10**-9\n",
+    "N=5\n",
+    "Lpt=6\n",
+    "Lpr=6\n",
+    "Lc=1\n",
+    "Ls =0.5\n",
+    "Lf=2\n",
+    "M=5\n",
+    "del_t=0.505\n",
+    "B=35\n",
+    "Ns=5\n",
+    "#a) Determination of loss−limited fiber length\n",
+    "z=(pt-pr-M-(Nc*Lc)-(Ns*Ls)-Lpt-Lpr)/Lf\n",
+    "print 'a) the loss−limited fiber is',z,'km'\n",
+    "#b) Determination of max BW for loss−limited fiber length\n",
+    "B_max=1/(5*del_t*z)\n",
+    "B_max=round(B_max,3)\n",
+    "print 'b) the max BW for loss−limited length is',B_max,'Gbps'\n",
+    "#c ) Determination of dispersion−limited length\n",
+    "z_disp=1000/(5*del_t*B)\n",
+    "z_disp=round(z_disp,2)\n",
+    "print 'the dispertion limited length is',z_disp,'km'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter2_Waveform_Spectra.ipynb b/Electronic_Communication_by_D._Roddy/Chapter2_Waveform_Spectra.ipynb
new file mode 100644
index 00000000..3ceb177d
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter2_Waveform_Spectra.ipynb
@@ -0,0 +1,64 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter2 Waveform spectra"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 2.13.1,Pg no.66"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The average energy is 0.0018 J\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "V=3\n",
+    "t=2*10**-3\n",
+    "R=10.0              #Determination of average energy\n",
+    "P=(V**2)/R          #Instantaneous power\n",
+    "U=P*t\n",
+    "print 'The average energy is',U,'J'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter4_Noise.ipynb b/Electronic_Communication_by_D._Roddy/Chapter4_Noise.ipynb
new file mode 100644
index 00000000..748bcbf7
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter4_Noise.ipynb
@@ -0,0 +1,549 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter 4 Noise"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.2.1,Pg.no 120"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of thermal noise power is 4.002e-15 W\n",
+      "The value of RMS noise voltage is 0.89 uV\n"
+     ]
+    }
+   ],
+   "source": [
+    "from math import sqrt\n",
+    "T=290.0\n",
+    "BW=1*10**6          #Noise bandwidth in hertz\n",
+    "k=1.38*10**-23      #Boltzman constant in J/K\n",
+    "R=50.0              #Determination of thermal noise power Pn\n",
+    "Pn=k*T*BW\n",
+    "#Pn=round(Pn,1)\n",
+    "print 'The value of thermal noise power is',Pn,'W'\n",
+    "#Determination of RMS noise voltage\n",
+    "En=sqrt(4*R*k*T*BW)\n",
+    "En=En*(10**6)\n",
+    "En=round(En,2)\n",
+    "print 'The value of RMS noise voltage is',En,'uV'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.2.2,Pg.no.122"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "a) i )The value of RMS noise voltage is 5.66 uV\n",
+      "   ii)The value of RMS noise voltage is 8949245.77828 uV\n",
+      "b)The value of RMS noise voltage is 10588890.4 uV\n",
+      "c)The value of RMS noise voltage is 4783573.08 uV\n"
+     ]
+    }
+   ],
+   "source": [
+    "from math import sqrt\n",
+    "R1=20000.0\n",
+    "R2=50000.0\n",
+    "k=1.38*10**-23              #Boltzman constant in J/K\n",
+    "T=290.0\n",
+    "BW=100*10**3       #Determination of thermal noise voltage for 20Kohm resistor\n",
+    "En1=sqrt(4*R1*k*T*BW)\n",
+    "En1=En1*(10**6)\n",
+    "En1=round(En1,2)\n",
+    "print 'a) i )The value of RMS noise voltage is',En1,'uV'\n",
+    "#Determination of thermal noise voltage for 50 kohm resistor\n",
+    "En2=En1*sqrt(R2/R1)\n",
+    "En2=En2*10**6\n",
+    "print '   ii)The value of RMS noise voltage is',En2,'uV'\n",
+    "#Determination of thermal noise voltage for 20K & 50k resistor in series\n",
+    "Rser=R1+R2           #Series combination of R1 & R2\n",
+    "En3=En1*sqrt(Rser/R1)\n",
+    "En3=En3*10**6\n",
+    "En3=round(En3,2)\n",
+    "print 'b)The value of RMS noise voltage is',En3,'uV'\n",
+    "#Determination of thermal noise voltage for 20K & 50k resistor in parellel\n",
+    "Rpar=(R1*R2)/(R1+R2)         #parallel combination of R1 & R2\n",
+    "En4=En1*sqrt(Rpar/R1)\n",
+    "En4=En4*10**6\n",
+    "En4=round(En4,2)\n",
+    "print 'c)The value of RMS noise voltage is',En4,'uV'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.2.3,Pg.no.128"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of Rd is 1.59 kohm\n",
+      "The value of effective noise voltage is 0.02 uV\n"
+     ]
+    }
+   ],
+   "source": [
+    "from math import sqrt,pi\n",
+    "f=120*10**6\n",
+    "c=25*10**-12         #capacitance of 12 pF\n",
+    "Q=30.0               #Q−factor of the ckt is 30\n",
+    "BW=10*10**3          #channel BW of the receiver is 10 KHz\n",
+    "k=1.38*10**-23       #Boltzman constant in J/K\n",
+    "T=290.0              #Room temp\n",
+    "#Determination of effective noise voltage Rd appearing at i /p at room temp\n",
+    "Rd=Q/(2*pi*f*c)\n",
+    "Rd=Rd/1000\n",
+    "Rd=round(Rd,2)\n",
+    "print 'The value of Rd is',Rd,'kohm'\n",
+    "Vn=sqrt(4*Rd*k*T*BW)\n",
+    "Vn=Vn*10**6\n",
+    "Vn=round(Vn,2)\n",
+    "print 'The value of effective noise voltage is',Vn,'uV'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.3.1,Pg.no.131"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of noise current In is 17.89 nA\n"
+     ]
+    }
+   ],
+   "source": [
+    "from math import sqrt\n",
+    "Idc=10**-3\n",
+    "Bn=10**6           #Effective noise BW=1 MHz\n",
+    "q=1.6*10**-19      #Charge on electron in coulombs\n",
+    "#Determination of noise component current In in DC current of Idc=1 mA\n",
+    "In=sqrt(2*Idc*q*Bn)\n",
+    "In=In*10**9\n",
+    "In=round(In,2)\n",
+    "print 'The value of noise current In is',In,'nA'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.11.1,Pg.no.135"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of shot noise current Ina is 4.0 nA\n",
+      "The value of noise voltage across Rs is 600000000.0 uV\n",
+      "The value of noise voltage across Rn is 6.93 uV\n",
+      "The value of thermal noise voltage at Rs is 4.9 uV\n",
+      "The value of total noise voltage Vn is 1000000.0 uV\n",
+      "The value of signal to noise ratio is -220.0 dB\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi,sqrt\n",
+    "#An amplifier is given\n",
+    "Rn=300.0        #Equivalent noise resistance\n",
+    "Ieq=5*10**-6    #Equivalent noise current is 5 uA\n",
+    "Rs=150.0        #Amplifier fed from 150 ohm,10 uV rms sinusoidal source\n",
+    "Vs=10*10**-6\n",
+    "Bn=10*10**6     #Noise BW is 10 MHz\n",
+    "#Assume the following\n",
+    "kT=4*10**-21    #k is Boltzman constant in J/K & T is room temp\n",
+    "q=1.6*10**-19   #Charge on electron in coloumbs\n",
+    "#Determination of shot noise current\n",
+    "Ina=sqrt(2*q*Ieq*Bn)\n",
+    "Ina=Ina*(10**9)\n",
+    "print 'The value of shot noise current Ina is',Ina,'nA'\n",
+    "#Noise voltage developed by this across source resistance is\n",
+    "V=Ina*Rs\n",
+    "V=V*(10**6)\n",
+    "V=round(V,2)\n",
+    "print 'The value of noise voltage across Rs is',V,'uV'\n",
+    "#Noise voltage developed across Rn resistance is\n",
+    "Vna=sqrt(4*Rn*kT*Bn)*10**6\n",
+    "Vna=round(Vna,2)\n",
+    "print 'The value of noise voltage across Rn is',Vna,'uV'\n",
+    "#Determination of thermal noise voltage from source\n",
+    "Vns=sqrt(4*Rs*kT*Bn)*10**6\n",
+    "Vns=round(Vns,2)\n",
+    "print 'The value of thermal noise voltage at Rs is',Vns,'uV'\n",
+    "#Determination of total noise voltage at input\n",
+    "Vn=(((V)**2)+((Vna)**2)+((Vns)**2))**(1/2)\n",
+    "Vn=Vn*(10**6)\n",
+    "print 'The value of total noise voltage Vn is',Vn,'uV'\n",
+    "#Determination of signal to noise ratio in dB\n",
+    "SNR=20*(math.log10(Vs/Vn))\n",
+    "print 'The value of signal to noise ratio is',SNR,'dB'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.12.1,Pg.no.136"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of output signal to noise ratio is 55.23 dB\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "SNR1=60.0\n",
+    "l=3.0           #Determination of output signal to noise ratio\n",
+    "SNR=(SNR1) -10*math.log10(l)\n",
+    "SNR=round(SNR,2)\n",
+    "print 'The value of output signal to noise ratio is',SNR,'dB'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.12.2,Pg.no.137"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of output signal to noise ratio is 40.0 dB\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "SNRdB1=60.0      #SNR is 60 dB for Ist link\n",
+    "SNRdB2=60.0      #SNR is 60 dB for IInd link\n",
+    "SNRdB3=40.0      #SNR is 40 dB for IIIrd link\n",
+    "#Determination of power in watt\n",
+    "snr1=10**(-SNRdB1/10)\n",
+    "snr2=10**(-SNRdB2/10)\n",
+    "snr3=10**(-SNRdB3/10)\n",
+    "#Determination of overall SNR\n",
+    "SNR=snr3\n",
+    "#Determination of total SNR in dB\n",
+    "SNRdB=10*(-math.log10(SNR))\n",
+    "print 'The value of output signal to noise ratio is',SNRdB,'dB'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.13.1,Pg.no.139"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of output signal to noise ratio is 28.0 dB\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "SNRin=35.0 #SNR at i /p of amplifier\n",
+    "F=7.0      #Noise figure of an amplifier\n",
+    "#Determination of output SNR\n",
+    "SNRout=SNRin-F\n",
+    "print 'The value of output signal to noise ratio is',SNRout,'dB'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.14.1,Pg.no.140"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 16,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of input noise is 0.08 pW\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "f=13.0  #Noise figure of an amplifier\n",
+    "Bn=1*10**6\n",
+    "kT=4*10**-21   #k is Boltzman constant in J/K & T is room temp\n",
+    "F=10**(f/10)\n",
+    "#Determination of equivalent amplifier input noise\n",
+    "Pna=(F-1)*kT*Bn*10**12\n",
+    "Pna=round(Pna,2)\n",
+    "print 'The value of input noise is',Pna,'pW'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.15.1,Pg.no.141"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 17,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The overall noise fig is 10.44 dB\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "f1=9.0     #Noise fig for amplifier\n",
+    "f2=20.0    #Noise fig for mixer\n",
+    "g=15.0     #power gain\n",
+    "#Converting dB in power ratio\n",
+    "F1=10**(f1/10)\n",
+    "F2=10**(f2/10)\n",
+    "G=10**(g/10)\n",
+    "#Determination of overall noise fig . reffered at i / p\n",
+    "F=F1+(F2-1)/G  #converting in dB\n",
+    "FdB=10*math.log10(F)\n",
+    "FdB=round(FdB,2)\n",
+    "print 'The overall noise fig is',FdB,'dB'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.17.1,Pg.no.143"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 18,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of noise factor is 1\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "F=6.0      #Noise fig .=6 dB\n",
+    "#Determination of noise factor\n",
+    "Fn=10**(6/10)\n",
+    "print 'The value of noise factor is',Fn"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.18.1,Pg.no.144"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 19,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of equivalent noise at room temp is 4306.19 k\n",
+      "The value of equivalent noise at noise temp=90 is 90.04 K\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "f=12.0 \n",
+    "Tm=290.0    #Room temp value\n",
+    "T=90.0\n",
+    "g=50.0      #calculating power ratio\n",
+    "F=10**(f/10)\n",
+    "G=10**(g/10)\n",
+    "#Determination of equivalent noise at room temp\n",
+    "Tem=(F-1)*Tm\n",
+    "Tem=round(Tem,2)\n",
+    "print 'The value of equivalent noise at room temp is',Tem,'k'\n",
+    "#Determination of equivalent noise at 90 k temp\n",
+    "Te=T+(Tem/G)\n",
+    "Te=round(Te,2)\n",
+    "print 'The value of equivalent noise at noise temp=90 is',Te,'K'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 4.19.1,Pg.no.146"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 20,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of hot temp Th is 7574.47 k\n",
+      "The value of equivalent noise temp Te is 759.14 K\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "enr=14.0\n",
+    "To=290.0          #Room temp in K\n",
+    "y=9.0             #Y−factor is 9 dB\n",
+    "#converting dB in power ratio\n",
+    "ENR=10**(enr/10)\n",
+    "Y=10**(y/10)      #From def of ENR the hot temp is\n",
+    "Th=To*(ENR+1)\n",
+    "Th=round(Th,2)\n",
+    "print 'The value of hot temp Th is',Th,'k'\n",
+    "#Determination of equivalent noise temp\n",
+    "Te=(Th-(Y*To))/(Y-1)\n",
+    "Te=round(Te,2)\n",
+    "print 'The value of equivalent noise temp Te is',Te,'K'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter5_Tuned_Small_Signal_Amplifiers,_Mixers_and_Active_Filters.ipynb b/Electronic_Communication_by_D._Roddy/Chapter5_Tuned_Small_Signal_Amplifiers,_Mixers_and_Active_Filters.ipynb
new file mode 100644
index 00000000..a9c1b03b
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter5_Tuned_Small_Signal_Amplifiers,_Mixers_and_Active_Filters.ipynb
@@ -0,0 +1,134 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter5 Tuned Small Signal Amplifiers, Mixers and Active Filters"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 5.4.1,Pg.no.162"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The voltage gain is -918.2\n",
+      "The Millar capacitance is 551.52 pF\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi\n",
+    "f=5*10**6\n",
+    "c=100*10**-12          #tuning capacitance in F\n",
+    "Q=150.0                #Q−factor of the ckt\n",
+    "Rl=5*10**3             #load resistance in ohm\n",
+    "Rc=40*10**3            #o/p reistance of transistor\n",
+    "Ic=500*10**-6          #transister collector current in A \n",
+    "C=0.6*10**-12          #collector to base capacitance in F\n",
+    "Vt=26*10**-3           #thermal voltage in V\n",
+    "#transe conductance is given as\n",
+    "gm=Ic/Vt\n",
+    "RD2=Q/(2*pi*f*c)\n",
+    "#At resonance the output admittance is purely conductive and is given as\n",
+    "Yo=(1/Rc)+(1/RD2)+(1/Rl)\n",
+    "#The voltage gain is given as\n",
+    "Av=-(gm/Yo)\n",
+    "Av=round(Av,2)\n",
+    "print 'The voltage gain is',Av\n",
+    "#The Millar capacitance is given as\n",
+    "Cm=(1-Av)*C*10**12\n",
+    "Cm=round(Cm,2)\n",
+    "print 'The Millar capacitance is',Cm,'pF'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 5.4.2,Pg.no.163"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The effective Q−factor is 12.68\n",
+      "The voltage gain is 62.14\n"
+     ]
+    }
+   ],
+   "source": [
+    "from math import pi\n",
+    "f=5*10**6               #in Hz\n",
+    "w0=2*pi*f\n",
+    "Q=100.0                 #Q−factor of the ckt\n",
+    "L=2*10**-6              #inductance expressed in H\n",
+    "Rs=1000.0               #source resistance in ohm\n",
+    "Ic=500*10**-6           #transister collector current in A \n",
+    "Vt=26*10**-3            #thermal voltage in V\n",
+    "hfe=200.0\n",
+    "C_be=10*10**-12         #in pF\n",
+    "#refer to problem 5.4.1\n",
+    "Av=78.0\n",
+    "Cm=47.0\n",
+    "gm=Ic/Vt\n",
+    "r_be=hfe/gm\n",
+    "#The dynamic resistance of the tuned ckt is\n",
+    "RD1=Q*w0*L             #The effective dynamic conductance is\n",
+    "RD1eff_1=(1/Rs)+(1/RD1)+(1/r_be)\n",
+    "RD1_eff=1/RD1eff_1            \n",
+    "#Tha effective Q−factor is\n",
+    "Qeff=RD1_eff/(w0*L)\n",
+    "Qeff=round(Qeff,2)\n",
+    "print 'The effective Q−factor is',Qeff\n",
+    "#The voltage gain refered to source is\n",
+    "Avs=RD1_eff*Av/Rs\n",
+    "Avs=round(Avs,2)\n",
+    "print 'The voltage gain is',Avs"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter6_Oscillators.ipynb b/Electronic_Communication_by_D._Roddy/Chapter6_Oscillators.ipynb
new file mode 100644
index 00000000..d8fc16c8
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter6_Oscillators.ipynb
@@ -0,0 +1,312 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter6 Oscillators"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 6.3.1,Pg.no.199"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "1.The minimum value of beta is 44.54\n",
+      "2.The value of resistor R= 21.6 Kohm\n",
+      "3.The value of capacitor is 4494.19 pF\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi,sqrt\n",
+    "f=400.0\n",
+    "rc= 10.0\n",
+    "Rc= 40.0      \n",
+    "#Minimum value of beta is given by Bomin= 23+(4*Ro /R)+(29*R/Ro)            \n",
+    "#For minimum beta Ro/R=2.7, we represent Ro/R=b\n",
+    "b=2.7\n",
+    "Bomin=23+(4*b)+(29*1/b)\n",
+    "Bomin=round(Bomin,2)\n",
+    "print '1.The minimum value of beta is',Bomin\n",
+    "#Determination of R and C components\n",
+    "#R0 is given by ( rc*Rc) /( rc+Rc)\n",
+    "R0=(rc*Rc)/(rc+Rc)\n",
+    "R=2.7* R0\n",
+    "print '2.The value of resistor R=',R,'Kohm'\n",
+    "c=1/(2*pi*f*R*sqrt(6+(4*b)))*10**9\n",
+    "c=round(c,2)\n",
+    "print '3.The value of capacitor is',c,'pF'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 6.3.2,Pg.no.200"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of capacitor is 767.44 pF\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi,sqrt\n",
+    "#given\n",
+    "f=800.0\n",
+    "R0=18.0\n",
+    "#calculations\n",
+    "R=100.0\n",
+    "c=1/(2*pi*f*R*sqrt(6+(4*R0/R)))*10**9      #Capacitance in pF\n",
+    "c=round(c,2)\n",
+    "print 'The value of capacitor is',c,'pF'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 6.3.3,Pg.no.201"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of capacitor is 614.0 pF\n",
+      "1.The required open−circuit voltage gain is 30.16\n",
+      "2.The value of gm is 6.03 mS\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "f=1000.0\n",
+    "Ro=5.0\n",
+    "R=100.0\n",
+    "c=1/(2*pi*f*R*sqrt(6+(4*R0/R)))*10**9\n",
+    "c=round(c,1)\n",
+    "print 'The value of capacitor is',c,'pF'\n",
+    "#The required open−circuit voltage gain is\n",
+    "Ao= 29+23*(Ro/R)+4*(Ro/R)**2\n",
+    "Ao=round(Ao,2)\n",
+    "print'1.The required open−circuit voltage gain is',Ao\n",
+    "gm=Ao/Ro\n",
+    "gm=round(gm,2)\n",
+    "print '2.The value of gm is',gm,'mS'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 6.4.1,Pg.no.205"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "1.The value of capacitor is 75.0 pF\n",
+      "2.The frequency of oscillation is 918881.49 Hz\n",
+      "3.The dynamic impedence of the tuned circuit 461880.22 ohm\n",
+      "4.The coil series resistance is 11.55 ohm\n",
+      "5.The value of gm is 1.15470052676e-05\n",
+      "6.The input resistance is 8660254.12 ohm\n",
+      "7.The frequency of oscillation is 918881.49 Hz\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi,sqrt\n",
+    "L=400*10**-6       #inductsnce in H\n",
+    "c1= 100.0          #capaitance in pF\n",
+    "c2= 300.0          #in pF\n",
+    "Q=200.0\n",
+    "Ro= 5*10**3\n",
+    "Bo=100.0           #beta value\n",
+    "#The tuning capacitance is\n",
+    "Cs=(c1*c2/(c1+c2))\n",
+    "Cs=round(Cs,2)\n",
+    "print '1.The value of capacitor is',Cs,'pF'\n",
+    "#the frequency of oscillation is obtained as\n",
+    "f=1/(2*pi*sqrt(L*Cs*10**-12))\n",
+    "f=round(f,2)\n",
+    "print '2.The frequency of oscillation is',f,'Hz'\n",
+    "#The dynamic impedence of the tuned circuit\n",
+    "wo= 2*pi*f\n",
+    "Rd=Q/(wo*Cs*10**-12)\n",
+    "Rd=round(Rd,2)\n",
+    "print '3.The dynamic impedence of the tuned circuit',Rd,'ohm'\n",
+    "#The coil series resistance is\n",
+    "r=wo*L/Q\n",
+    "r=round(r,2)\n",
+    "print '4.The coil series resistance is',r,'ohm'\n",
+    "#The capacitor raio c= c1/c2=1/3, and therefore 1− c2/B0∗c1 = 1\n",
+    "#The starting value of gm is therefore given by\n",
+    "c= c1/c2\n",
+    "gm=(1/Ro)*c +(c+3+2)*(1/Rd)\n",
+    "print '5.The value of gm is',gm\n",
+    "#Assuming the input resistance is that of the transistor alone\n",
+    "R1=Bo/gm\n",
+    "R1=round(R1,2)\n",
+    "print '6.The input resistance is',R1,'ohm'\n",
+    "wo2=1/((L*Cs*10**-12)+(1/R1*Ro*c1*c2*10**-12*10**-12))\n",
+    "wo=sqrt(wo2)\n",
+    "f=wo/(2*pi)\n",
+    "f=round(f,2)\n",
+    "print '7.The frequency of oscillation is',f,'Hz'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 6.6.1,Pg.no.211"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The value of capacitor is 5.16 pF\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "Co=20.0  #in pF\n",
+    "Vd=-7    #reverse bias voltage in volt\n",
+    "#constant pottential of junction is 0.5\n",
+    "a=0.5    #for abrupt junction\n",
+    "Cd=Co/(1-(Vd/0.5))**a\n",
+    "Cd=round(Cd,2)\n",
+    "print 'The value of capacitor is',Cd,'pF'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 6.6.2,Pg.no.212"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "1.The total tuning capacitor is 9.38 pF\n",
+      "2.The frequency of oscillation is 5196593.1 Hz\n",
+      "3.The total tuning capacitor is 3.99 pF\n",
+      "4.The frequency of oscillation is 7967713.03 Hz\n"
+     ]
+    }
+   ],
+   "source": [
+    "from math import pi,sqrt\n",
+    "#given\n",
+    "C1=300.0\n",
+    "C2=300.0\n",
+    "Cc=20.0\n",
+    "L=100.0\n",
+    "#calculations\n",
+    "# A) With zero applied bias , the total tuning capacitor is \n",
+    "Vd1=0\n",
+    "a=0.5\n",
+    "Co=20.0\n",
+    "Cd1=Co/(1-(Vd1/0.5))**a\n",
+    "Cs1=1/((1/C1)+(1/C2)+(1/Cc)+(1/Cd1))\n",
+    "Cs1=round(Cs1,2)\n",
+    "print '1.The total tuning capacitor is',Cs1,'pF'\n",
+    "#The frequency of oscillation is\n",
+    "f=1/(2*pi*sqrt(L*10**-6*Cs1*10**-12))\n",
+    "f=round(f,2)\n",
+    "print '2.The frequency of oscillation is',f,'Hz'\n",
+    "Vd2=-7\n",
+    "Cd2=Co/(1-(Vd2/0.5))**a\n",
+    "Cs2=1/((1/C1)+(1/C2)+(1/Cc)+(1/Cd2))\n",
+    "Cs2=round(Cs2,2)\n",
+    "print '3.The total tuning capacitor is',Cs2,'pF'\n",
+    "f=1/(2*pi*sqrt(L*10**-6*Cs2*10**-12))\n",
+    "f=round(f,2)\n",
+    "print '4.The frequency of oscillation is',f,'Hz'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter7_Receivers.ipynb b/Electronic_Communication_by_D._Roddy/Chapter7_Receivers.ipynb
new file mode 100644
index 00000000..1cf5b9ae
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter7_Receivers.ipynb
@@ -0,0 +1,157 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter7 Receivers"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 7.3.1,Pg.no.227"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The freq tuning range is 1005000 Hz to 2055000 Hz\n",
+      "The tuning range ratio of oscillator is 2 ohm\n",
+      "The capacitor tuning range ratio of oscillator is 4\n",
+      "The tuning range ratio of RF−ckt is 2\n",
+      "The capacitor tuning range ratio of RF−ckt is 4\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "fs_min=550*10**3\n",
+    "fs_max=1600*10**3\n",
+    "IF=455*10**3 \n",
+    "#Determination of freq tuning ranges\n",
+    "fo_min=fs_min+IF\n",
+    "fo_max=fs_max+IF\n",
+    "print 'The freq tuning range is',fo_min,'Hz to',fo_max,'Hz'\n",
+    "Rf=(fo_max)/(fo_min)   #calculation of freq tuning range ratio\n",
+    "print 'The tuning range ratio of oscillator is',Rf,'ohm'\n",
+    "Rc=Rf**2               #calculation of capacitance tuning range ratio\n",
+    "print 'The capacitor tuning range ratio of oscillator is',Rc\n",
+    "#For RF section\n",
+    "Rf1=fs_max/fs_min;\n",
+    "print 'The tuning range ratio of RF−ckt is',Rf1\n",
+    "Rc1=Rf1**2\n",
+    "print 'The capacitor tuning range ratio of RF−ckt is',Rc1"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 7.4.1,Pg.no.230"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The Cs min is 84.0 *10^-12 F\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "Rco=8.463\n",
+    "Rfo=2.909\n",
+    "Rcs=4.182\n",
+    "Rfo=2.045\n",
+    "fo_max =2055.0*10**3\n",
+    "fo_min=1005.0*10**3\n",
+    "Cs_max=350.0\n",
+    "#For the RF section\n",
+    "Cs_min=Cs_max/Rcs\n",
+    "Cs_min=round(Cs_min,0)\n",
+    "print 'The Cs min is',Cs_min,'*10^-12','F'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 7.6.1,Pg.no.234"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Image freq is 1930.0 Hz\n",
+      "Image rejection is -36.98\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "IF=465.0  #IF in KHz\n",
+    "fs=1000   #Tuning freq in KHz\n",
+    "Q=50.0    #Quality factor\n",
+    "#Oscillator freq fo is given as\n",
+    "fo=fs+IF;\n",
+    "#a) Image freq is given as\n",
+    "fi=fo+IF\n",
+    "print 'Image freq is',fi,'Hz'\n",
+    "y=fi/fs-fs/fi\n",
+    "#b) image rejection is given as\n",
+    "Ar=1/sqrt(1+(y*Q)**2)\n",
+    "Ar_dB=20*math.log10(Ar)\n",
+    "Ar_dB=round(Ar_dB,2)\n",
+    "print 'Image rejection is',Ar_dB"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter8_Amplitude_Modulation.ipynb b/Electronic_Communication_by_D._Roddy/Chapter8_Amplitude_Modulation.ipynb
new file mode 100644
index 00000000..b9d22f20
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter8_Amplitude_Modulation.ipynb
@@ -0,0 +1,182 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter8 Amplitude Modulation"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 8.3.1,Pg.no.257"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The modulation index is 0.55\n",
+      "The ratio of side lengths L1/L2 is 3.44\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import pi,sqrt\n",
+    "vpp=11.0    #peak to peak voltage of modulating signal\n",
+    "vcp=10.0    #carrier peak voltage\n",
+    "#Determination of modulation index\n",
+    "E_max=vcp+(vpp/2)\n",
+    "E_min=vcp-(vpp/2)\n",
+    "m=(E_max -E_min)/(E_max+E_min)\n",
+    "print 'The modulation index is',m\n",
+    "#determination of k ratio of side lengths\n",
+    "L1_L2=E_max/E_min\n",
+    "L1_L2=round(L1_L2,2)\n",
+    "print 'The ratio of side lengths L1/L2 is',L1_L2"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {
+    "collapsed": true
+   },
+   "source": [
+    "## Example 8.5.1,Pg.no.260"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The modulation index is 0.6\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "fc=10*10**6      #Carrier freq\n",
+    "fm=5*10**3       #Modullating freq\n",
+    "vp=10.0\n",
+    "vm=6.0          #Determination of modulation index\n",
+    "m=vm/vp\n",
+    "m=round(m,1)\n",
+    "print 'The modulation index is',m"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 8.7.1,Pg.no.263"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The modulation index is 0.9\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt\n",
+    "I=12.0\n",
+    "Ic=10.0     \n",
+    "#Determination of modulation index\n",
+    "m=sqrt(2*(((I/Ic)**2) -1))\n",
+    "m=round(m,1)\n",
+    "print 'The modulation index is',m"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 8.11.1,Pg.no.274"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Yp= 6.28e-05 j\n",
+      "Zp= 15915.5\n",
+      "The max modulation index is 1.59\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "from math import sqrt,pi\n",
+    "fm=10*10**3           #modulation freq\n",
+    "c=1000*10**-12\n",
+    "R=10*10**3\n",
+    "Yp=complex((1/R),(2*(pi)*fm*c))   #admittance of RC load\n",
+    "Ypi=Yp.imag*10**5\n",
+    "Ypi=round(Ypi,2)*10**-5\n",
+    "print 'Yp=',Ypi,'j'\n",
+    "Zp=1/sqrt(((Yp.real)**2)+((Yp.imag)**2))\n",
+    "Zp=round(Zp,1)\n",
+    "print 'Zp=',Zp\n",
+    "#Determination of max modulation index\n",
+    "m=Zp/R\n",
+    "m=round(m,2)\n",
+    "print 'The max modulation index is',m"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/Chapter9_Single_Sideband_Modulation.ipynb b/Electronic_Communication_by_D._Roddy/Chapter9_Single_Sideband_Modulation.ipynb
new file mode 100644
index 00000000..a033a332
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/Chapter9_Single_Sideband_Modulation.ipynb
@@ -0,0 +1,100 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Chapter9 Single SideBand Modulation"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 9.2,Pg.no.349"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The efficiency is 70.0 %\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "Nd=7.0\n",
+    "N_start=1\n",
+    "N_stop=1\n",
+    "N_parity=1\n",
+    "Nt= Nd + N_start+ N_stop + N_parity\n",
+    "eff=Nd/Nt*100\n",
+    "print 'The efficiency is',eff,'%'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example 9.6,Pg.no.358"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "hammming bits required= 5\n"
+     ]
+    }
+   ],
+   "source": [
+    "import math\n",
+    "m=21.0\n",
+    "for n in range (1,10):   #we choose range of 1 to 10\n",
+    "        a=m+n+1 \n",
+    "        b=2**n\n",
+    "        if b>=a:\n",
+    "           print 'hammming bits required=',n\n",
+    "           break\n",
+    "           end\n",
+    "           end"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.10"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Electronic_Communication_by_D._Roddy/screenshots/1.png b/Electronic_Communication_by_D._Roddy/screenshots/1.png
new file mode 100644
index 00000000..3d66b2fd
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/screenshots/1.png
diff --git a/Electronic_Communication_by_D._Roddy/screenshots/12.png b/Electronic_Communication_by_D._Roddy/screenshots/12.png
new file mode 100644
index 00000000..7618eea0
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/screenshots/12.png
diff --git a/Electronic_Communication_by_D._Roddy/screenshots/9.png b/Electronic_Communication_by_D._Roddy/screenshots/9.png
new file mode 100644
index 00000000..52938734
--- /dev/null
+++ b/Electronic_Communication_by_D._Roddy/screenshots/9.png