Hey Mike
Ground stations have fixed locations on Earth. This makes the calculation of elevation angles relatively straightforward since the ground station's position doesn't change over time.
Unlike a ground station, an aircraft moves along a trajectory. This dynamic movement means the position relative to a satellite changes continuously, requiring real-time calculation of elevation angles throughout the simulation.
The elevation angle can be calculated based on the positions of aircraft and satellite as follows.
function elevationAngle = calculateElevationAngle(aircraftPos, satPos)
[lat1, lon1, alt1] = aircraftPos;
[lat2, lon2, alt2] = satPos;
lat1 = deg2rad(lat1);
lon1 = deg2rad(lon1);
lat2 = deg2rad(lat2);
lon2 = deg2rad(lon2);
dLat = lat2 - lat1;
dLon = lon2 - lon1;
a = sin(dLat/2)^2 + cos(lat1) * cos(lat2) * sin(dLon/2)^2;
% This is a simplified calculation for spherical Earth
c = 2 * atan2(sqrt(a), sqrt(1-a));
distance = 6371000 * c; % Earth radius
elevationAngle = atan2((alt2 - alt1), distance);
elevationAngle = rad2deg(elevationAngle);
end
Using the above script which computes the elevation angle, the restrictions can be imposed by using simple ‘if’ statement as follows.
minElevationAngle = 30;
maxElevationAngle = 90;
for t = 1:length(timeOfArrival)
elevationAngle = calculateElevationAngle(aircraftPos, satPos);
if elevationAngle < minElevationAngle || elevationAngle > maxElevationAngle
% aircraftPos, satPos are positions at time t.
fprintf('Invalid elevation angle at time %s: %f degrees\n', timeOfArrival(t), elevationAngle);
break;
end
end
I hope this helps.
