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Exercise.m
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Exercise.m
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clear all;
close all;
clc;
format long;
% opening the rinex files
fileObs = fopen([pwd '/INPUT/test.11o']); % observation file
fileNav = fopen([pwd '/INPUT/test.11n']); % navigation message file
% structure of SV
SV(1:37) = struct(...
'navData', ...
struct(...
'year',0,... % [year]
'month',0,... % [month]
'day',0,... % [day]
'hour',0,... % [h]
'minute',0,... % [min]
'second',0,... % [sec]
'af0',0,... % [sec]
'af1',0,... % [sec/sec]
'af2',0,... % [sec/sec^2]
'IODE',0,... % [-]
'Crs',0,... % [m]
'DeltaN',0,... % [rad/sec]
'M0',0,... % [rad]
'Cuc',0,... % [rad]
'e',0,... % [eccentricity]
'Cus',0,... % [rad]
'sqrtA',0,... % [rad]
'TOE',0,... % [sec of GPS week], time of ephemeris
'Cic',0,... % [rad]
'OMEGA0',0,... % [rad]
'Cis',0,... % [rad]
'i0',0,... % [rad]
'Crc',0,... % [m]
'omega',0,... % [rad]
'OMEGA_DOT',0,... % [rad/sec]
'IDOT',0,... % [rad]
'CodesOnL2Channel',0,... % [m]
'GPSWeek',0,... % [-]
'GPSWeek2',0,... % [-]
'SVaccuracy',0,... %
'SVhealth',0,... %
'TGD',0,... % [sec], time group delay
'IODCIssueOfData',0,... %
'TransmissionTimeOfMessage',0,... % [sec]
'Spare1',0,... %
'Spare2',0,... %
'Spare3',0,...
'Ek',0, ...
'Ek_dot',0),...
'obs',zeros(3600, 10),... % [year, month, day, hour, minute, second, C1[m], L1[cycle], D1[Hz], SN1[dBHz]]
'POSITION',zeros(3600,3)); % [X[m], Y[m], Z[m]], ECEF coordinates
numEpochs = 0;
% reading the observation file:
[SV, numEpochs] = readObs(SV, fileObs, numEpochs);
% reading the navigation message file
[SV] = readNav(SV, fileNav);
%% Task 2
%************** Part1 *************************
GPSWeekSecond = 511200; % [Sec]
OMEGA_dot_e = 7.2921151467e-5; % [rad/sec] WGS 84 value of the earth's rotation rate
[x_17_ref y_17_ref z_17_ref] = Satellite_Position(SV,17,GPSWeekSecond,1);
%************** Part2 *************************
% to cover the total orbital period, we need sidereal day
Sidereal_day = 23*3600+56*60; % [Sec] one Sidereal day
t_sid = (0:100:Sidereal_day);
[x_17 y_17 z_17] = Satellite_Position(SV,17,t_sid,1);
figure
plot3(x_17,y_17,z_17); % The Satellite trajectory
hold on; grid on
% The Earth
r_e=1e7;
% b = a*sqrt(1-e^2); % minor axis for ellipse
% x_e = sqrt(a^2-b^2); y_e = sqrt(abs(b^2-a^2)); % coordinates of the Earth
% [x,y,z]=ellipsoid(x_e,y_e,0,r,r,r,20); % Earth placed in the focal length of the Satellite
[x_e,y_e,z_e]=ellipsoid(0,0,0,r_e,r_e,r_e,20); % Earth at the center 0,0,0
surf(x_e, y_e, z_e,'FaceColor','y', 'FaceAlpha', 0.2);
axis equal;
% box on;
xlabel('x-axis (m)'); ylabel('y-axis (m)'); zlabel('z-axis (m)');
% The Satellite
[x_s,y_s,z_s] = sphere(20);
r_s = 3e6;
surf( r_s*(x_s)+x_17_ref, r_s*(y_s)+y_17_ref, r_s*(z_s)+z_17_ref ) % satellite with radius r centred at GPSWeekSeconds time ref.
colormap([1 0 0; 1 0 0])
str1 = '\leftarrow Satellite at ref. Time = 511200';
text(x_17_ref,y_17_ref,z_17_ref,str1);
title 'The trajectory of the Satellite with respect to the EC-inertial coordinates system';
legend ('Trajectory','Earth', 'Satellite');
% plot in 2D
longitude = linspace(0,180,length(x_17));
latitude = linspace(-90,90,length(y_17));
figure
plot(longitude,x_17)
hold on; grid on
xlabel('Longitude [Deg]'); ylabel('X Coord. [m]');
title 'The Longitude against the X coordinates';
legend ('Longitude [Deg]','X Coord. [m]');
figure
plot(y_17,latitude)
hold on; grid on
xlabel('Y Coord. [m]'); ylabel('Latitude [Deg]');
title 'The Latitude against the Y coordinates';
legend ('Y Coordinates','Latitude');
%% Task 3
rot = 0;
t_sid_half = (0:100:Sidereal_day/2);
[x_17_rot_0 y_17_rot_0 z_17_rot_0] = Satellite_Position(SV,17,t_sid_half,0);
figure
plot3(x_17_rot_0,y_17_rot_0,z_17_rot_0); % The Satellite trajectory
hold on; grid on
% The Earth
surf(x_e, y_e, z_e,'FaceColor','y', 'FaceAlpha', 0.2);
axis equal;
% box on;
xlabel('x-axis (m)'); ylabel('y-axis (m)'); zlabel('z-axis (m)');
% The Satellite
surf( r_s*(x_s)+x_17_rot_0(1), r_s*(y_s)+y_17_rot_0(1), r_s*(z_s)+z_17_rot_0(1) ) % satellite with radius r centred at GPSWeekSeconds time ref.
colormap([1 0 0; 1 0 0])
str1 = '\leftarrow Satellite num.17';
text(x_17_ref,y_17_ref,z_17_ref,str1);
title 'The trajectory of the Satellite with respect to the EC-inertial coordinates system';
legend ('Trajectory','Earth', 'Satellite');
%% Task 4
figure
for i=1:37
[x y z] = Satellite_Position(SV,i,t_sid_half,0);
plot3(x,y,z); % The Satellite trajectory
hold on; grid on
% The Earth
surf(x_e, y_e, z_e,'FaceColor','y', 'FaceAlpha', 0.2);
axis equal;
% box on;
xlabel('x-axis (m)'); ylabel('y-axis (m)'); zlabel('z-axis (m)');
% % The Satellite
% surf( r_s*(x_s)+x_17_rot_0(1), r_s*(y_s)+y_17_rot_0(1), r_s*(z_s)+z_17_rot_0(1) ) % satellite with radius r centred at GPSWeekSeconds time ref.
% colormap([1 0 0; 1 0 0])
% str1 = '\leftarrow Satellite num.17';
% text(x_17_ref,y_17_ref,z_17_ref,str1);
title 'The Orbits of the Satellite with respect to the EC-inertial coordinates system and the rotational is zero';
legend ('Earth','Orbit');
end