LOS

MATLAB

Site = LOS(r1,r2)

Description

Determines if there is line of site between two satellites assuming a circular earth. This algorithm should only be used for altitudes above 100 km, For altitudes below 100km, use GeomStruct or SunRiseSet. Satellite positions should be in the ECF coordinate frame. LOS can determine if an asset is sunlit by passing in the satellite ECF position vector in as r1 and the Julian date as r2. In that case r2 must have the same dimensions as r1, except for the last dimension that contain the position vector.

Parameters

Parameters	Description
r1 [array]	Satellite 1's position vector in ECF coordinates (m)
r2 [array]	Satellite 2's position vector (m) or the Julian date for sunlit calculations

Return Values

Return Values	Description
Site [array]	0 - no line-of-site or in earth's shadow, or 1 - line-of-site or sunlit

References

D. A. Vallado, Fundamentals of astrodynamics and applications. New York: McGraw-Hill, 1997.

Examples

>> ECF = [-7321730.222, -41523595.498, 22014.656]; % GeoSync at -100 Long

>> JD = Gregorian2Julian('01-Jul-2005 12:00:00'); % Checking for sunlit

>> r1 = repmat(ECF,24,1);

>> r2 = JD + [0:23]'/24;

>> Site = LOS(r1,r2)