GroundStation.TrackingInterference(Spacecraft, Variable, Variable, Array, Array) Method

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Description

Returns the number of elements that have been populated into the EventTime and EventType arrays. The arrays are populated with the time and type of interference events, where an event can be the start or end of an 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.

 

 

Timing Precision Mode

This page describes functionality in millisecond timing precision mode. Millisecond timing precision mode is deprecated and will be removed in a future release. We recommend that you migrate your Mission Plans to nanosecond timing precision mode.

Click here to see the documentation for this object in nanosecond timing precision mode.

 

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

Note: This method has a state. See the Methods and Properties with State page for more information.

 

Method Signature

GroundStation.TrackingInterference(

Spacecraft trackedSpacecraft,

Variable interferenceAngle,

Variable interferingCelestialObject,

Array EventTime,

Array EventType)

 

 

Arguments

trackedSpacecraft

Description:

The Spacecraft to be tracked by the GroundStation.

 

 

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

 

 

EventTime

Description:

The time that the event occurred.

 

The FF_Preferences.IntervalEventReportingBehavior property controls whether the start of propagation is reported as an event. 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.

 

 

EventType

Description:

The type of the event that occurred. Event Type == 1 is beginning of interference. Event Type == 2 is end of interference.

 

 

 

Return Value

Type:

number

 

 

Returns the number of elements populated into EventType and EventTime arrays

 

Syntax

myVariable1 = myGroundStation1.TrackingInterference(mySpacecraft1, myVariable2, myVariable3, myArray1, myArray2);

 

 

Example 1

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

 

Spacecraft Spacecraft1;

GroundStation GroundStation1;

 

Variable i;

Variable TrackingTimes;

Array EventTime;

Array EventType;

String scEventType;

String scEventTime;

DataTableWindow scReport({scEventType, scEventTime}, 0);

 

While(Spacecraft1.ElapsedDays < 1);

 

          TrackingTimes = GroundStation1.TrackingInterference(Spacecraft1, 50 /* Interference Angle */, 11 /* Body ID for the Sun */, EventTime, EventType);

 

          If(TrackingTimes > 0) then;

                      For i = 0 to TrackingTimes-1 step 1;

                                  Switch (EventType[i]);

                                              Case 1:

                                                          scEventType = "Start of Tracking Interference: ";

                                                          scEventTime = EventTime[i].EpochFormat();

                                                          Update scReport;

                                                          Break;

                                              Case 2:

                                                          scEventType = "End of Tracking Interference: ";

                                                          scEventTime = EventTime[i].EpochFormat();

                                                          Update scReport;

                                  End;

                      End;

          End;

 

          Step Spacecraft1;

 

End;

 

 

Output:

 

scEventType

scEventTime

Start of Tracking Interference:

End of Tracking Interference:

Jan 01 2020 18:57:14.691

Jan 01 2020 19:01:58.139

 

 

 

See also

GroundStation Object

GroundStation.TrackingInterference

Coverage and Contact Analysis Guide

GroundStations Guide