{ "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "# Chapter 3: The Amplitude Modulation" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.10: example_9.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "// page no 126\n", "// prob no 3.10\n", "f_car=8*10^6;f_mod1=2*10^3;f_mod2=3.5*10^3;\n", "//Signal is LSB hence o/p freq is obtained by subtracting f_mod from f_car\n", "f_out1=f_car-f_mod1; \n", "disp('MHz',f_out1/(10^6),'The o/p freq f_out1 is ');\n", "f_out2=f_car-f_mod2; \n", "disp('MHz',f_out2/(10^6),'The o/p freq f_out1 is ');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.11: example_10.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "// page no 127\n", "// prob no 3.11\n", "//Refering the fig. 3.17\n", "//From fig it is clear that thee waveform is made from two sine waves \n", "Vp=12.5;//Since Vp-p is 25V from fig hence individual Vp is half of Vp-p\n", "Rl=50;//Load resistance is 50 ohm\n", "//Determination of average power\n", "Vrms=Vp/sqrt(2);\n", "P=((Vrms)^2)/Rl;\n", "disp('W',P,'The value of average power of signal is ');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.1: example_1.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "// page no 105\n", "// prob no 3.1\n", "Erms_car=2; f_car=1.5*10^6;f_mod=500;Erms_mod=1;// given\n", "// Equation requires peak voltages & radian frequencies\n", "Ec=sqrt(2)*Erms_car; Em=sqrt(2)*Erms_mod;\n", "wc=2*%pi*f_car; wm=2*%pi*f_mod;t=1;\n", "// Therefore the equation is \n", "disp('v(t) = (2.83+1.41*sin(3.14*10^3*t))*sin(9.42*10^6*t) V');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.2: example_2.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "//page no 106\n", "//prob no 3.2\n", "// To avoid the round-off errors we should use the original voltage values\n", "Em=1;Ec=2;\n", "m=Em/Ec;\n", "disp(m,'m=');\n", "disp('v(t) = 2.83(1+0.5*sin(3.14*10^3*t))*sin(9.42*10^6*t) V','The equation can be obtained as');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.3: example_3.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "//page no 109\n", "//prob no 3.3\n", "E_car=10;E_m1=1;E_m2=2;E_m3=3;\n", "m1=E_m1/E_car;\n", "m2=E_m2/E_car;\n", "m3=E_m3/E_car;\n", "mT=sqrt(m1^2+m2^2+m3^2);\n", "disp(mT,'The modulation index is');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.4: example_4.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "//page no 110\n", "//prob no 3.4\n", "//refer fig 3.2\n", "E_max=150; E_min=70;// voltages are in mV\n", "m=(E_max-E_min)/(E_max+E_min);\n", "disp(m,'The modulation index is');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.6: example_5.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "//page no 114\n", "//prob no 3.6\n", "B=10*10^3;\n", "// maximum modulation freq is given as \n", "fm=B/2;\n", "disp('Hz',fm,'The maximum modulation freq is');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.7: example_6.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "//page no 116\n", "//prob no 3.7\n", "// AM broadcast transmitter\n", "Pc=50;m=0.8;//power is in kW\n", "Pt=Pc*(1+m^2 /2);\n", "disp('kW',Pt,'The total power is');" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.8: example_7.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "// page no 328\n", "// prob no 8.6\n", "//2 kHz tone is present on channel 5 of group 3 of supergroup\n", "//signal is lower sided so\n", "fc_channel_5=92*10^3;\n", "fg=fc_channel_5 - (2*10^3);// 2MHz baseband signal\n", "// we know group 3 in the supergroup is moved to the range 408-456 kHz with a suppressed carrier frequency of 516kHz\n", "f_s_carr=516*10^3;\n", "fsg=f_s_carr - fg;\n", "disp(fsg);" ] } , { "cell_type": "markdown", "metadata": {}, "source": [ "## Example 3.9: example_8.sce" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "collapsed": true }, "outputs": [], "source": [ "clc;\n", "//page no 122\n", "//prob no. 3.9\n", "// refer fig 3.14\n", "// from spectrum we can see that each of the two sidebands is 20dB below the ref level of 10dBm. Therefore each sideband has a power of -10dBm i.e. 100uW.\n", "power_of_each_sideband = 100;\n", "Total_power = 2* power_of_each_sideband;\n", "disp('uW',Total_power,'The total power is');\n", "div=4; freq_per_div=1;\n", "sideband_separation = div * freq_per_div;\n", "f_mod= sideband_separation/2;\n", "disp('kHz',f_mod,'The modulating freq is ');\n", "// Even if this siganl has no carrier, it still has a carrier freq which is midway between the two sidebands. Therefore\n", "carrier_freq = 10;\n", "disp('MHz',carrier_freq,'The carrier freq');" ] } ], "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 }