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 {
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	   "source": [
       "# Chapter 3: The Geostationary orbit"
	   ]
	},
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 3.1: Calculate_the_azimuth_angle_for_an_earth_station_antenna.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
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"source": [
"//Variable Declaration\n",
"Pss=-90   //Location of geostationary satellite(degrees)\n",
"PE=-100   //Longitude of the earth station antenna(degrees)\n",
"LE=35     //Latitude of the earth station antenna(degrees)\n",
"//Calculation\n",
"B=PE-Pss   //Angle between planes containing a and c(degrees)\n",
"b=acos(cos(B)*cos(LE)) //Angle of plane containing b(radians)\n",
"A=asin(sin(abs(B*3.142/180))/sin(b)) //Angle between planes containing b and c (radians)\n",
"A=A*180/3.142  //Converting A into degrees\n",
"//LE>0 and B<0 by observation\n",
"Az= 180-A     //Azimuth angle(degrees)\n",
"//Result\n",
"printf('The azimuth angle for the given earth station antenna is %.2f degrees',Az)"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 3.2: Find_the_range_and_antenna_elevation_angle.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
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	   "outputs": [],
"source": [
"//Variable Declaration\n",
"R=6371  //Radius of earth (km)\n",
"aGSO= 42164  //Circumference of earth(km)\n",
"b=0.632 //values of b from Example 3.1 (radians)\n",
"//Calculation\n",
"d=sqrt(R**2+aGSO**2-2*R*aGSO*cos(b)) //Range of earth station antenna (km)\n",
"El=acos(aGSO*sin(b)/d)*180/%pi  //Elevation angle(degrees)\n",
"//Results\n",
"printf('The range of earth station antenna is %.0f km',d)\n",
"printf('Elevation angle is %.0f degrees',El)"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 3.3: Determine_the_angle.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"//Variable Declaration\n",
"LE=49  //Latitude of earth station(degrees)\n",
"aGSO=42164  //Circumference of earth(km)\n",
"R=6371  //Radius of earth(km)\n",
"//Calculation\n",
"d=(R**2+aGSO**2-2*R*aGSO*cos(LE*3.142/180))**0.5  //Range of earth station antenna\n",
"El0=acos(aGSO*sin(LE*3.142/180)/d)  //Elevation angle(radians)\n",
"El0=El0*180/3.142  //Converting El0 to degrees\n",
"delta=round(90-El0-LE)  //Angle of tilt required for polar mount\n",
"//Results\n",
"printf('The Angle of tilt required for polar mount is %d degrees',delta)"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 3.4: Determine_the_limits_of_visibility.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"//Variable Declaration\n",
"LE=48.42  //Latitude of earth station(degrees)\n",
"PE=-89.26 //Longitute of earth station(degrees)\n",
"Elmin=5  //Minimum angle of elevation(degrees)\n",
"aGSO=42164  //Circumference of earth(km)\n",
"R=6371  //Radius of earth(km)\n",
"//Calculation\n",
"Smin=90+Elmin\n",
"S=asin(R*sin(Smin*3.142/180)/aGSO)*180/%pi  //Angle subtended at the satellite(degrees)\n",
"b=180-Smin-S   //Angle of plane containing b(degrees)\n",
"B=acos(cos(b*3.142/180)/cos(LE*3.142/180))*180/%pi//Angle between the planes containing a and c(degrees)\n",
"//Results\n",
"printf('The satellite limit east of the earth station is at %d Degrees approximately',round(PE+B))\n",
"printf('The satellite limit west of the earth station is at %d Degrees approximately',round(PE-B))"
   ]
   }
,
{
		   "cell_type": "markdown",
		   "metadata": {},
		   "source": [
			"## Example 3.5: calculate_the_longitude.sce"
		   ]
		  },
  {
"cell_type": "code",
	   "execution_count": null,
	   "metadata": {
	    "collapsed": true
	   },
	   "outputs": [],
"source": [
"//Variable Declaration\n",
"y=2000       //year\n",
"d=223.153    //day\n",
"n=1.002716   //mean motion(1/day)\n",
"w=272.5299   //rate of regression of nodes(degrees)\n",
"e=0.000352   //Eccentricity\n",
"W=247.9161   //Rate of regression of line of apsides(degrees)\n",
"M=158.0516   //Mean Anomaly at given time\n",
"JD00=2451543.5  //Julian days for Jan 0.0 2000\n",
"//Calculation\n",
"JD=JD00+d  //Julian days for given day\n",
"JDref=2415020   //Reference Julian days\n",
"JC=36525\n",
"T=(JD-JDref)/JC  //Time in julian Centuries\n",
"UT=d-223  //Universal Time, fraction of the day\n",
"GST=(99.6910+36000.7689*T+0.004*T**2)*3.142/180  //GST(radians)\n",
"UT=2*%pi*UT //Universal time converted to fraction of earth rotation (radians)\n",
"GST=(GST+UT)*180/3.1421\n",
"GST=(modulo(GST,360))//using fmod multiplr revolutions are removed (degrees)\n",
"v=M+2*e*M  //True Anomaly(degrees)\n",
"Pssmean=W+w+M-GST //longitude for INTELSAT(degrees)\n",
"Pssmean=modulo(Pssmean,360) //fmod removes multiple revolutions\n",
"Pss=w+W+v-GST//longitude for INTELSAT(degrees)\n",
"Pss=modulo(Pss,360)//fmod removes multiple revolutions\n",
"//Results\n",
"printf('The longitude of INTELSAT 805 is %.3f Degrees',Pss)\n",
"printf('The average longitude of INTELSAT 805 is %.3f Degrees',Pssmean)\n",
"// Note : Answers may be different because of rounding error. Please check by calculating all variables."
   ]
   }
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