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+{
+"cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "# Chapter 3: Amplitude Modulation"
+ ]
+ },
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.1_A: AM_Sidebands.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"Fc=500;//carrier frequency in kHz\n",
+"Fm=1;// message signal frequency in kHz\n",
+"//a)\n",
+"\n",
+"USB=Fc+Fm;\n",
+"LSB=Fc-Fm;\n",
+"disp(USB,'USBI(in kHZ)=');\n",
+"disp(LSB,'LSB(in kHz)=');\n",
+"\n",
+"//b)\n",
+"\n",
+"Bandwidth=USB-LSB;\n",
+"disp(Bandwidth,'Bandwidth(in kHZ)=')\n",
+"//c)\n",
+"\n",
+"Fm=1.5;//message signal frequency in kHz\n",
+"\n",
+"USB1=Fc+Fm;\n",
+"LSB1=Fc-Fm;\n",
+"disp(USB1,'USB(in kHz)=');\n",
+"disp(LSB1,'LSB(in kHZ)=');\n",
+"\n",
+"\n",
+"//d)\n",
+"\n",
+"Amplitude=[0 0 0 0 0 0 0 0 0 5 10 5 0]; //sample values as denoted in textbook\n",
+"frequency=490:1:502;\n",
+"\n",
+" plot2d3(frequency,Amplitude); \n",
+"xlabel('Frequency(in kHZ)');\n",
+"ylabel('Amplitude(in V)');"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.1: amplitude_modulatio.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"Vm=3;// amplitude of message signal in V\n",
+"Vc=5;//amplitude of carrier signal in V\n",
+"m=Vm/Vc; //modulation index\n",
+"disp('modulation index');\n",
+"disp(m,'=');\n",
+"disp('Upper Sideband Frequency(in MHz)');\n",
+"Fm=4;//Frequency in KHz\n",
+"Fc=5;//Frequency in MHz\n",
+"disp(Fc+(Fm*10^(-3)),'=');\n",
+"disp('Lower Sideband Frequency(in MHz)');\n",
+"disp(Fc-(Fm*10^(-3)),'=');\n",
+"disp('AMplitude of each Sideband(in V)');\n",
+"disp(m*Vc/2,'=');"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.2_A: Amplitude_Modulatio.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clear;\n",
+"clc;\n",
+"\n",
+"\n",
+"Fm=3; //frequency of message signal\n",
+"Fc=8; //frequency of carrier signal\n",
+"Ea=5;\n",
+"Eb=10;\n",
+"m=Ea/Eb; //modulation index\n",
+"\n",
+"disp(m,'m=');\n",
+"USf=Fc+Fm*10^(-3);//Upper Sideband frequency\n",
+"LSf=Fc-Fm*10^(-3);//Lower sideband frequency\n",
+"disp(USf,'USf(Mhz)=');\n",
+"disp(LSf,'LSf(Mhz)=');\n",
+"Amp=m*Eb/2;// amplitude of each sideband\n",
+"disp(Amp,'amp(v)=');\n",
+"\n",
+"\n",
+"\n",
+"function[x,Vm,Vc]=ampmod(Ea,Eb,m,Fc,Fm)\n",
+" t=0:0.005:5;\n",
+" \n",
+" Vm = Ea*sin(2*%pi*Fm*t);\n",
+" Vc = Eb*sin(2*%pi*Fc*t);\n",
+" \n",
+" x = ((Eb+Ea*sin(2*%pi*Fm*t))).*(sin(2*%pi*Fc*t));\n",
+" \n",
+" subplot(3,1,2);\n",
+" plot2d(t,x);\n",
+" title('Amplitude Modulated Signal');\n",
+"endfunction\n",
+"\n",
+"ampmod(Ea,Eb,m,Fc,Fm)//amplitude modulation"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.2: Total_power_of_AM_wave.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"Pc=300;// Power of the carrier in W\n",
+"m=0.6// modulation index\n",
+"Pt=Pc*(1+(m^2)/2); //total power\n",
+"disp('Total power in the modulated wave(in W) is');\n",
+"disp(Pt);"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.3_A: Efficiency_of_DSBFC.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"disp('efficiency(n)=(useful power/total power)*100%');\n",
+"disp(' =total sideband power/(total sideband power+carrier power)*100%');\n",
+"\n",
+"syms m Pc\n",
+"N=[((m^2)*Pc/2)/(Pc*(1+(m^2)/2))];\n",
+"disp('*100% ',N);\n",
+"\n",
+"disp('----------------------------------------------------------------');\n",
+"m=0.7 //modulation index\n",
+"\n",
+"\n",
+"n=[m^2/(m^2+2)]*100; //efficiency\n",
+"disp(n,'the percentage of useful power is ');"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.3: Modulation_index.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"Pt=11.5;//Total power in kW\n",
+"Pc=10;// Carrier power in kW\n",
+"//a)\n",
+"\n",
+"m_square=2*((Pt/Pc)-1);\n",
+"m=sqrt(m_square);//modulation index\n",
+"\n",
+"//b)\n",
+"m2=0.5;\n",
+"mt=sqrt(m^2 +m2^2); \n",
+"Pt=Pc*(1+mt^2/2); //total power in kW\n",
+"\n",
+"disp(m,'modulation index is ');\n",
+"disp(Pt,'Total carrier power(in kW) ');"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.4_A: DSBFC.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"Vc=8;// carrier signal voltage in V\n",
+"m=1;//modulation index\n",
+"R=8;//resistance in ohms\n",
+"//a)\n",
+"\n",
+"Pc=Vc^2/(2*R); \n",
+"disp(Pc,'power of the carrier(in W) is');\n",
+"Ps=m^2*Pc/4;\n",
+"disp(Ps,'Power in each Side-Bands(in W)');\n",
+"\n",
+"//b)\n",
+"disp(2*Ps,'Total sideband Power(in W)');\n",
+"\n",
+"//c)\n",
+"disp(Pc+2*Ps,'Total Power of Modulated wave(in W)');\n",
+"\n",
+"//d)\n",
+"disp(2*Ps/(Pc+2*Ps)*100,'Efficiency Percentage');"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.4: Modulation_index_and_power.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"m1=0.3;\n",
+"m2=0.4;\n",
+"m3=0.5;\n",
+"m4=0.6; //modulation indices\n",
+"Pc=150;//power of carrier in Watts\n",
+"\n",
+"mt=sqrt(m1^2+m2^2+m3^2+m4^2); //total modulation index\n",
+"\n",
+"Pt=Pc*(1+mt^2/2);//Total transmitted power in Watts\n",
+"\n",
+"Ps=(mt^2)*Pc/4; //Sideband Power in Watts\n",
+"\n",
+"disp(mt,'Total Modulation index');\n",
+"\n",
+"disp(Pt,'Total Transmitted Power (in W)');\n",
+"\n",
+"//change in answer as compared to book ,due to approximation error..\n",
+"disp(Ps,'Sideband Power(in W)')\n",
+"\n",
+"\n",
+""
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.5_A: Amplitude_Modulatio.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"m1=0.3;\n",
+"m2=0.4;\n",
+"m3=0.5;\n",
+"m4=0.6; //modulation indices\n",
+"Pc=80;// Power in carrier signal \n",
+"\n",
+"mt=sqrt(m1^2+m2^2+m3^2+m4^2);\n",
+"\n",
+"//a)\n",
+"disp(mt,'Total Coefficient of Modulation ');\n",
+"\n",
+"//calculation error in book\n",
+"\n",
+"//b)\n",
+"Ps=(mt^2)*Pc/2;\n",
+"disp(Ps,'Sideband powers(in W) ');\n",
+"\n",
+"//c)\n",
+"disp(Pc+2*Ps,'Total Transmitted Power(in W)');\n",
+"\n",
+"//d)\n",
+"disp((Ps/(Pc+2*Ps))*100,'Efficiency Percentage');"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.5: Peak_Envelope_Power_and_average_power.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"fLSB1=395;\n",
+"fLSB22=397.5;// Two LSB frequencies in kHz\n",
+"E1=4;\n",
+"E2=3;//peak voltages of modulating signal in V\n",
+"R=60;//resistor in ohms\n",
+"\n",
+"Et=sqrt(E1^2+E2^2);\n",
+"\n",
+"Erms=Et*0.707;\n",
+"\n",
+"PEP=((Et*0.707)^2)/R; //Pak Envelope Power in W\n",
+"\n",
+"Avg_Power=PEP/2;\n",
+"\n",
+"disp(PEP,'Peak Envelope Power(in W)');\n",
+"disp(Avg_Power,'Average Power(in W)');"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.7_A: Diagonal_Clipping.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"Fc=10;//carrier Frequency in kHz\n",
+"R=15;//Resistance in Kohms\n",
+"C=660;//Capacitance in pF\n",
+"a=1/R;\n",
+"b=2*%pi*Fc*10^(3)*C*10^(-12);\n",
+"Y=a+%i*b;\n",
+"Z=1/abs(Y);\n",
+"//after rounding off\n",
+"Z=12.83//Impedence in Kohms\n",
+"m=Z/(R);//modulation index\n",
+"disp(m,'MAximum modulation index to avoid diagonal clipping is');"
+ ]
+ }
+,
+{
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3.8_A: Sideband_Frequencies.sce"
+ ]
+ },
+ {
+"cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+"source": [
+"clc;\n",
+"clear;\n",
+"\n",
+"\n",
+"syms Ec Fc Fm pi t\n",
+"\n",
+"Wave=Ec*cos(2*pi*Fm*t)*cos(2*pi*Fc*t)+Ec*sin(2*pi*Fm*t)*sin(2*pi*Fc*t);\n",
+" disp('when the wave is');\n",
+" disp(Wave);\n",
+"\n",
+"f_upper=Ec*cos(2*pi*(Fc+Fm)*t); \n",
+"disp('We get the upper sideband as');\n",
+"disp(f_upper);\n",
+"\n",
+"\n",
+"f_lower=Ec*cos(2*pi*(Fc-Fm)*t); \n",
+"disp('We get the lower sideband as');\n",
+"disp(f_lower);\n",
+"\n",
+"\n",
+"\n",
+"\n",
+""
+ ]
+ }
+],
+"metadata": {
+ "kernelspec": {
+ "display_name": "Scilab",
+ "language": "scilab",
+ "name": "scilab"
+ },
+ "language_info": {
+ "file_extension": ".sce",
+ "help_links": [
+ {
+ "text": "MetaKernel Magics",
+ "url": "https://github.com/calysto/metakernel/blob/master/metakernel/magics/README.md"
+ }
+ ],
+ "mimetype": "text/x-octave",
+ "name": "scilab",
+ "version": "0.7.1"
+ }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
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