Spacecraft.FOVTimes(Variable, Sensor) Method

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Description

Returns the entry and exit times when celestialBodyToView enters and leaves the Spacecraft's field of view as well as the azimuth and elevation of the argument in sensorToUse's coordinate frame.

 

Timing Precision Mode

This page describes functionality in nanosecond timing precision mode.

Click here to see the documentation for this object in millisecond 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

Spacecraft.FOVTimes(

Variable celestialBodyToView,

Sensor sensorToUse)

 

 

Arguments

celestialBodyToView

Description:

The numerical indentifier of the celestial body to use in the field of view calculation. 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.

 

 

 

sensorToUse

Description:

Sensor to use for the field of view calculation.

 

 

 

Return Value

Type:

string

 

 

Returns the entry and exit times when the argument Spacecraft, GroundStation, Star, or celestial body enters and leaves the Spacecraft's field of view as well as the azimuth and elevation of the argument in the Spacecraft Sensor's coordinate frame. If the Spacecraft has no active Sensors, the azimuth and elevation are reported in the Spacecraft's body coordinate frame.

 

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

 

Syntax

myString1 = mySpacecraft1.FOVTimes(myVariable1, mySensor1);

 

 

Example 1

This topic demonstrates how to generate a report of a Spacecraft's contact with a Celestial Object using a specific Sensor on the Spacecraft.

 

Spacecraft Spacecraft1;

 

// Configure Spacecraft orbit and add a Sensor to be used by the Spacecraft.FOVTime() method

Spacecraft1.I = 0;

Spacecraft1.AddSensor("Sensor1");

Spacecraft1.AddSensor("Sensor2");

Spacecraft1.Sensors[1].BoresightUnitVector = {0, 0, -1};

 

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

While(Spacecraft1.ElapsedDays < 1);

 

          Report Spacecraft1.FOVTimes(10 /*Body ID for the Moon*/, Spacecraft1.Sensors[1]) to "SC_FOVTimes_Var.txt";

          Step Spacecraft1;

 

End;

 

Or

 

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

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

 

          Report Spacecraft1.FOVTimes(10 /*Body ID for the Moon*/, Spacecraft1.Sensors[1]) to "SC_FOVTimes_Var.txt";

          Step Spacecraft1;

 

End;

 

 

Output:

 

Note: Output generated using nanosecond timing precision mode.

 

FOV Event               Type     Epoch                               Azimuth (deg)     Elevation (deg)

Moon --> Sensor2        Entry     Jan 01 2020 00:50:38.012695312     159.495404428      60.000227309

Moon --> Sensor2        Exit      Jan 01 2020 01:05:57.055664062      20.409416031      60.003045072

Moon --> Sensor2        Entry     Jan 01 2020 02:29:32.900390625     160.122246340      60.002861285

Moon --> Sensor2        Exit      Jan 01 2020 02:44:55.019531250      19.780697525      60.003750252

Moon --> Sensor2        Entry     Jan 01 2020 04:08:27.714843750     160.753375144      60.000168300

Moon --> Sensor2        Exit      Jan 01 2020 04:23:52.983398437      19.148732363      60.000556882

Moon --> Sensor2        Entry     Jan 01 2020 05:47:22.602539062     161.383367481      60.000912535

Moon --> Sensor2        Exit      Jan 01 2020 06:02:50.800781250      18.518552109      60.001787311

Moon --> Sensor2        Entry     Jan 01 2020 07:26:17.490234375     162.014689943      60.001065712

Moon --> Sensor2        Exit      Jan 01 2020 07:41:48.544921875      17.887255495      60.002962323

Moon --> Sensor2        Entry     Jan 01 2020 09:05:12.377929687     162.647266554      60.000756774

Moon --> Sensor2        Exit      Jan 01 2020 09:20:46.215820312      17.254675244      60.003833916

Moon --> Sensor2        Entry     Jan 01 2020 10:44:07.338867187     163.279117527      60.004247136

Moon --> Sensor2        Exit      Jan 01 2020 10:59:43.813476562      16.620576307      60.004167824

Moon --> Sensor2        Entry     Jan 01 2020 12:23:02.226562500     163.915361909      60.002627752

Moon --> Sensor2        Exit      Jan 01 2020 12:38:41.337890625      15.984603689      60.003835003

Moon --> Sensor2        Entry     Jan 01 2020 14:01:57.187500000     164.551915228      60.004233919

Moon --> Sensor2        Exit      Jan 01 2020 14:17:38.789062500      15.346513707      60.002910660

Moon --> Sensor2        Entry     Jan 01 2020 15:40:52.075195312     165.192955647      60.000002585

Moon --> Sensor2        Exit      Jan 01 2020 15:56:36.166992187      14.706454715      60.001641015

Moon --> Sensor2        Entry     Jan 01 2020 17:19:47.109375000     165.832141298      60.002655084

Moon --> Sensor2        Exit      Jan 01 2020 17:35:33.471679687      14.064936110      60.000296083

Moon --> Sensor2        Entry     Jan 01 2020 18:58:42.143554687     166.473428299      60.003065626

Moon --> Sensor2        Exit      Jan 01 2020 19:14:30.629882812      13.424323311      60.003495202

Moon --> Sensor2        Entry     Jan 01 2020 20:37:37.177734375     167.116783892      60.000900087

Moon --> Sensor2        Exit      Jan 01 2020 20:53:27.788085937      12.781141164      60.002728401

Moon --> Sensor2        Entry     Jan 01 2020 22:16:32.285156250     167.760467700      60.000372724

Moon --> Sensor2        Exit      Jan 01 2020 22:32:24.873046875      12.137369911      60.002706515

Moon --> Sensor2        Entry     Jan 01 2020 23:55:27.465820312     168.404402191      60.001443367

Moon --> Sensor2        Stop      Jan 02 2020 00:00:00.000000000     155.245432008      76.123125095

 

 

 

See also

Spacecraft Object

Spacecraft.FOVTimes

Spacecraft Propagation Guide

Coverage and Contact Analysis Guide