{
"cells": [
 {
		   "cell_type": "markdown",
	   "metadata": {},
	   "source": [
       "# Chapter 8: Optical Receiver Operation"
	   ]
	},
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 7.q: Determine_maximum_response_time.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"// Question 7  page 8.55\n",
"\n",
"clc;\n",
"clear;\n",
"\n",
"w=25d-6;    //width\n",
"v=3d4;      //velocity\n",
"\n",
"t=w/v;      //computing drift time\n",
"BW=(2*%pi*t)^-1;        //computing bandwidth\n",
"rt=1/BW;    //response time\n",
"rt=rt*10^9;\n",
"\n",
"printf('\nMaximum response time is %.2f ns.',rt);\n",
"\n",
"//Answer in the book is given as 5.24ns deviation of 0.01ns"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 8.10_1: Find_signal_to_noise_ratio.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"// Example 8.10.1  page 8.25\n",
"\n",
"clc;\n",
"clear;\n",
"\n",
"//erfc 4.24 is given to be 2d-9\n",
"\n",
"SN=(2*sqrt(2)*4.24)^2;  //computing optical SNR\n",
"SN=round(SN);\n",
"SN1=sqrt(SN);       //computing electrical SNR\n",
"printf('\nOptical SNR is %d.\nElectrical SNR is %d.',SN,SN1);"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 8.11_1: Find_photon_energy.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"// Example 8.11.1  page 8.26\n",
"\n",
"clc;\n",
"clear;\n",
"\n",
"P=1d-9;     //probability of error\n",
"eta=1;\n",
"N= -log(P);\n",
"N1=round(N);\n",
"printf('Thus %.1f or %d photons are required for maintaining 10^-9 BER.\nAssuming eta=1;\nE=%.1f*hv.',N,N1,N);"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 8.17_1: Calculate_shot_noise_and_thermal_noise.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"// Example 8.17.1  page 8.46\n",
"\n",
"clc;\n",
"clear;\n",
"\n",
"lamda=0.85d-6;\n",
"h=6.626d-34;    //plank's constant\n",
"c=3d8;      //speed of light\n",
"q=1.6d-19;  //charge of electron\n",
"eta=65/100; //quantum efficiency\n",
"P0=300d-9;  //optical power\n",
"Id=3.5;    //dark current\n",
"B=6.5d6;     //bandwidth\n",
"K=1.39d-23; //Boltzman constant\n",
"T=293;      //temperature\n",
"R=5d3;     //load resister\n",
"Ip= 10^9*eta*P0*q*lamda/(h*c);\n",
"Its=10^9*(2*q*B*(Ip+Id));\n",
"Its=sqrt(Its);\n",
"printf('\nrms shot noise current is %.2f nA.',Its);\n",
"\n",
"It= 4*K*T*B/R;\n",
"It=sqrt(It);\n",
"It=It*10^9;\n",
"printf('\nThermal noise is %.2f nA.',It);\n",
"\n",
"//answer given in book for Thermal noise it is 4.58nA, deviation is 0.02nA."
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 8.17_2: Find_signal_to_noise_ratio.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"// Example 8.17.2  page 8.47\n",
"\n",
"clc;\n",
"clear;\n",
"\n",
"lamda=0.85d-6;\n",
"h=6.626d-34;    //plank's constant\n",
"c=3d8;      //speed of light\n",
"q=1.6d-19;  //charge of electron\n",
"eta=65/100; //quantum efficiency\n",
"P0=300d-9;  //optical power\n",
"Id=3.5;    //dark current\n",
"B=6.5d6;     //bandwidth\n",
"K=1.39d-23; //Boltzman constant\n",
"T=293;      //temperature\n",
"R=5d3;     //load resister\n",
"F_dB=3;     //noise figure\n",
"F=10^(F_dB/10);\n",
"Ip=10^9*eta*P0*q*lamda/(h*c);\n",
"Its=10^9*(2*q*B*(Ip+Id));\n",
"It1= 4*K*T*B*F/R;\n",
"\n",
"SN= Ip^2/(Its+It1);\n",
"SN_dB=10*log10(SN);\n",
"SN=SN/10^4;\n",
"\n",
"printf('\nSNR is %.2f*10^4 or %.2f dB.',SN,SN_dB);\n",
"\n",
"//answer given in the book is 6.16*10^4 (deviation of 0.9) and 47.8dB (deviation of 0.16dB)\n",
""
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 8.18_1: Calculate_maximum_load_resistance.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"// Example 8.18.1  page 8.48\n",
"\n",
"clc;\n",
"clear;\n",
"\n",
"Cd=7d-12;\n",
"B=9d6;\n",
"Ca=7d-12;\n",
"\n",
"R=(2*3.14*Cd*B)^-1;\n",
"B1=(2*3.14*R*(Cd+Ca))^-1;\n",
"R=R/1000;\n",
"B1=B1/10^6;\n",
"printf('\nThus for 9MHz bandwidth maximum load resistance is %.2f Kohm\nNow if we consider input capacitance of following amplifier Ca then Bandwidth is %.2fMHz\nMaximum post detection bandwidth is half.',R,B1);\n",
"\n",
"//answer for resistance in the book is 4.51Kohm, deviation of 0.01Kohm, while for bandwidth it is 4.51 MHz, deviation of 0.01MHz"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 8.3_1: Find_quantum_efficiency_and_minimum_incident_power.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"// Example 8.3.1  page 8.9\n",
"\n",
"clc;\n",
"clear;\n",
"\n",
"P=10^-9;    //probability of error\n",
"eta=1;      //ideal detector\n",
"h=6.626d-34 //plank's constant\n",
"c=3d8;     //speed of light\n",
"lamda=1d-6; //wavelength\n",
"B=10^7;     //bit rate\n",
"\n",
"Mn= - log(P);\n",
"printf('\n The quantum imit at the receiver to maintain bit error rate 10^-9 is (%.1f*h*f)/eta.',Mn);\n",
"f=c/lamda\n",
"Popt= 0.5*Mn*h*f*B/eta;     //computing optical power\n",
"Popt_dB = 10 * log10(Popt) + 30;    //optical power in dbm\n",
"Popt=Popt*10^12;\n",
"\n",
"printf('\nMinimum incident optical power is %.1f W or %.1f dBm.',Popt,Popt_dB);"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 8.3_2: Calculate_incident_optical_power.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"// Example 8.3.2  page 8.11\n",
"\n",
"clc;\n",
"clear;\n",
"\n",
"SN_dB=60;    //signal to noise ratio\n",
"h=6.626d-34 //plank's constant\n",
"c=3d8;     //speed of light\n",
"lamda=1.3d-6; //wavelength\n",
"eta=1;\n",
"B=6.5d6;     //Bandwidth\n",
"\n",
"SN=10^(SN_dB/10);\n",
"f=c/lamda\n",
"Popt= 2*SN*h*f*B/eta;     //computing optical power\n",
"Popt_dB = 10 * log10(Popt) + 30;    //optical power in dbm\n",
"Popt=Popt*10^6;\n",
"printf('\nIncident power required to get an SNR of 60 dB at the receiver is %.4f microWatt or %.3f dBm',Popt,Popt_dB);\n",
"printf('\nNOTE - Calculation error in the book.\nThey have take SN as 10^5 while calculating, which has lead to an error in final answer');\n",
"\n",
"//Calculation error in the book.They have take SN as 10^5 while calculating, which has lead to an error in final answer\n",
"//answer in the book 198.1nW and -37.71 dBm"
   ]
   }
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