GroundStation.TrackingInterference(Spacecraft, Variable, Variable) Method

Returns a formatted string which can be reported to an output file using the Report command. For each interference period, the report will include the start time, end time, and duration of the interference between the GroundStation and the trackedSpacecraft due to interferingCelestialObject.

FreeFlyer calculates interference based on the times when the center of the interfering object is within the cone. If you want to model a non-zero angular width for an interfering object, you can add half the angular width of that object (as seen from the GroundStation) to the desired interference half-angle to get the total cone half-angle.

Note: When more than one interfering object is specified, ALL of these objects (as opposed to ANY) must lie within the interference cone for the tracking to be considered interfered.

The TrackingInterference method will account for refraction if refraction modeling is turned on using the GroundStation.RefractionModelType property.

Note: This is an interval method. See the Interval Methods page for more information.

Method Signature

Arguments

interferenceAngle
Description:	The cone half angle about the GroundStation-to-Spacecraft vector used to determine interference.
Units:	deg
Valid Range:	-360 ≤ interferenceAngle ≤ 360

interferingCelestialObject

Description:

The ID(s) for the interfering CelestialObject(s). Body ID's 1-11 are assigned to the default Solar System objects, as shown below. Custom CelestialObjects will have body ID's starting at 12 and assigned in the order they are created.

Valid Values:

Celestial Object	Value
Mercury	Mercury.BodyID or 1
Venus	Venus.BodyID or 2
Earth	Earth.BodyID or 3
Mars	Mars.BodyID or 4
Jupiter	Jupiter.BodyID or 5
Saturn	Saturn.BodyID or 6
Uranus	Uranus.BodyID or 7
Neptune	Neptune.BodyID or 8
Pluto	Pluto.BodyID or 9
Moon	Moon.BodyID or 10
Sun	Sun.BodyID or 11
<Custom CelestialBody>	<Custom CelestialBody>.BodyID, starting at 12 and assigned in the order the custom CelestialObjects are created.

Repeatable:

1 to 30 times

Return Value

Returns a formatted string which includes the start time, end time, and duration when a GroundStation tracking a Spacecraft is interfered with by a Star, Celestial Object, or another Spacecraft.

The FF_Preferences.IntervalEventReportingBehavior property controls whether the start and end of propagation are reported as events. By default, if the interference starts before the beginning of the propagation span, FreeFlyer will label the start of the propagation as the start of the interference. If the interference extends past the end of the propagation span, FreeFlyer labels the end of propagation as the end of the interference.

Syntax

This example demonstrates how to generate a report of a GroundStation's tracking interference with a Celestial Object.

Spacecraft Spacecraft1;

GroundStation GroundStation1;

// *** For Millisecond Mode Only ***

While (Spacecraft1.ElapsedDays < 1);

Report GroundStation1.TrackingInterference(Spacecraft1, 50 /* Interference Angle */, 10 /*Body ID for the Moon*/) to "GS_TrackingInterf_CO.txt";

Step Spacecraft1;

End;

// *** For Nanosecond Mode Only ***

While (Spacecraft1.ElapsedTime < TIMESPAN(1 days));

Report GroundStation1.TrackingInterference(Spacecraft1, 50 /* Interference Angle */, 10 /*Body ID for the Moon*/) to "GS_TrackingInterf_CO.txt";

Step Spacecraft1;

End;

Output:

Note: Output generated using nanosecond timing precision mode.

TrackingInterference Event Entry Epoch Exit Epoch Duration(min)

GroundStation1 --> Spacecraft1 Jan 01 2020 17:21:38.144531250 Jan 01 2020 17:25:26.367187500 3.803710938