Access Analysis to Ground Points

Access analysis from a ground point to an orbit can be defined with the GroundPoint keyword:

Access GroundPointAccess AccessModel orbit_name ground_point_name

Two access models are supported. The Standard model uses a variable step size based on the rate of change in true anomaly to locate the next access window. Once the access window is located, a bisection method is used to refine the precise rise and set times. This method is robust and fast. A significantly slower Debug option is also available that uses a small fixed step size to search for access windows. By default, access is generated based on line if sight visibility from the ground point to the satellite. This occurs when the elevation of the satellite w.r.t. the ground point, relative to the plane tangent to the ellipsoid, is zero. Currently, only the minimum elevation is configurable through an additional line:

MinimumElevation d

The following illustrates creating a ground point location named gp01 where positive latitude implies north and positive longitude implies east. Access to this location by a satellite named leosat is to be performed with a minimum ground elevation constraint of -5 degrees.
AngleUnits  Degrees;
GroundPoint gp01 LLA  43.0  30.0  0.0;
Access  GroundPointAccess  Standard  leosat gp01
                           MinimumElevation  -5.0;
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