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+{
+ "cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "# Chapter 13 : Multiplexing and Multiple Access Techniques"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 1 : pg 437"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 1,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "a)The number of signals are 250.0\n",
+ "b)The number of signals are 125.0\n",
+ "c)The number of signals are 6.0\n",
+ "d)The number of signals are 71.0\n"
+ ]
+ }
+ ],
+ "source": [
+ " \n",
+ "# page no 437\n",
+ "# prob no 13_1\n",
+ "#calculate the no. of signals in all cases\n",
+ "from math import log\n",
+ "#given\n",
+ "freq_band=1.*10**6;\n",
+ "# A)For SSBSC AM, the bandwidth is the same as the maximunm modulating freq.\n",
+ "fmax=4.*10**3;\n",
+ "#calculations and results\n",
+ "B=fmax;\n",
+ "no_of_signal=freq_band/B;\n",
+ "print 'a)The number of signals are ',no_of_signal\n",
+ "# B)For DSB AM, the bandwidth is twice the maximunm modulating freq.\n",
+ "B=2*fmax;\n",
+ "no_of_signal=freq_band/B;\n",
+ "print 'b)The number of signals are ',no_of_signal\n",
+ "# C)Using Carson's Rule to approximate the bandwidth\n",
+ "f_max=15.*10**3; deviation=75.*10**3;\n",
+ "B=2*(deviation + f_max);\n",
+ "no_of_signal=freq_band/B;\n",
+ "print 'c)The number of signals are ',round(no_of_signal)\n",
+ "# D)Use Shannon-Hartley theorem to find the bandwidth\n",
+ "C=56.*10**3;M=4.;#for QPSK\n",
+ "B=C/(2*log(M) /log(2));\n",
+ "no_of_signal=freq_band/B;\n",
+ "print 'd)The number of signals are ',round(no_of_signal)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 2 : pg 444"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 2,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "The noise power at BW=30 kHz is -129.059 dBm\n",
+ "The noise power at BW=10 MHz is -103.83 dBm\n",
+ "The value of SNR for BW=30 kHz is 19.059 dB\n",
+ "The value of SNR for BW=10 MHz is -6.17 dB\n"
+ ]
+ }
+ ],
+ "source": [
+ " \n",
+ "# page no 444\n",
+ "# prob no 13_2\n",
+ "#calculate the value of SNR and noise power in both cases\n",
+ "#Voice transmisssion occupies 30 kHz.Spread spectrum is used to increase BW to 10MHz\n",
+ "from math import log10\n",
+ "#given\n",
+ "B1=30.*10**3;#BW is 30 kHz\n",
+ "B2=10.*10**6;#BW is 10 MHz\n",
+ "T=300.;#noise temp at i/p\n",
+ "PN=-110.;#signal has total signal power of -110 dBm at receiver\n",
+ "k=1.38*10**-23;#Boltzmann's const in J/K\n",
+ "#calculations and results\n",
+ "#Determination of noise power at B1=30kHz\n",
+ "PN1=10*(log10(k*B1*T/10**-3));\n",
+ "print 'The noise power at BW=30 kHz is',round(PN1,3),'dBm'\n",
+ "#Determination of noise power at B2=10MHz\n",
+ "PN2=10*(log10(k*B2*T/10**-3));\n",
+ "print 'The noise power at BW=10 MHz is',round(PN2,3),'dBm'\n",
+ "#Determination of SNR for 30kHz BW\n",
+ "SNR1=PN-PN1;\n",
+ "print 'The value of SNR for BW=30 kHz is',round(SNR1,3),'dB'\n",
+ "#Determination of SNR for 10MHz BW\n",
+ "SNR2=PN-PN2;\n",
+ "print 'The value of SNR for BW=10 MHz is',round(SNR2,3),'dB'"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 3 : pg 445"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 3,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Time required for each freq 0.1 sec/hop\n"
+ ]
+ }
+ ],
+ "source": [
+ " \n",
+ "# page no 445\n",
+ "# prob no 13_3\n",
+ "#calculate the time required\n",
+ "#given\n",
+ "no_of_freq_hops =100.; total_time_req=10.;\n",
+ "#calculations\n",
+ "time_for_each_freq = total_time_req / no_of_freq_hops;\n",
+ "#results\n",
+ "print 'Time required for each freq',time_for_each_freq,'sec/hop'"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 4 : pg 446"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 4,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "The no of signal changes i.e. symbol rate is 80000.0 baud\n"
+ ]
+ }
+ ],
+ "source": [
+ " \n",
+ "# page no 446\n",
+ "# prob no 13_4\n",
+ "#calculate the no. of signal changes\n",
+ "from math import log\n",
+ "#given\n",
+ "bit_rate=16.*10**3;#in bps\n",
+ "#chip_rate =10:1;\n",
+ "no_of_chip=10.;\n",
+ "#calculations\n",
+ "total_bit_rate=no_of_chip*bit_rate;\n",
+ "m=4;n=log(m)/log(2);\n",
+ "symbol_rate = total_bit_rate/n;\n",
+ "#results\n",
+ "print 'The no of signal changes i.e. symbol rate is ',symbol_rate,'baud'"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Example 5 : pg 447"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 5,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "The value of BW after spreading 10.0 MHz\n",
+ "The value of processing gain 16.99 dB\n",
+ "The value of SNR after spreading in dB 3.01 dB\n"
+ ]
+ }
+ ],
+ "source": [
+ " \n",
+ "# page no 447\n",
+ "# prob no 13_5\n",
+ "#calculate the value of BW, SNR\n",
+ "#signal with bandwidth Bbb=200 kHz & SNR=20 dB spred at chip rate 50:1\n",
+ "from math import log10\n",
+ "#given\n",
+ "Bbb=200.*10**3;#Bandwidth\n",
+ "Gp=50.;#chip rate\n",
+ "SNR_in=20.;#SNR is 20 dB without spreading\n",
+ "#calculations and results\n",
+ "#Determination of BW after spreading\n",
+ "Brf=Gp*Bbb;\n",
+ "print 'The value of BW after spreading',Brf/10**6,'MHz'\n",
+ "#Converting into dB \n",
+ "Gp_dB=10*log10(Gp);\n",
+ "print 'The value of processing gain',round(Gp_dB,3),'dB'\n",
+ "#Determination of SNR after spreadng\n",
+ "SNR_out=SNR_in-Gp_dB;\n",
+ "print 'The value of SNR after spreading in dB',round(SNR_out,3),'dB'"
+ ]
+ }
+ ],
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+ "display_name": "Python 2",
+ "language": "python",
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+ "language_info": {
+ "codemirror_mode": {
+ "name": "ipython",
+ "version": 2
+ },
+ "file_extension": ".py",
+ "mimetype": "text/x-python",
+ "name": "python",
+ "nbconvert_exporter": "python",
+ "pygments_lexer": "ipython2",
+ "version": "2.7.11"
+ }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
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