Satellite control. More...

#include <Satellite.h>

Public Member Functions
bool	AddTelescope (Telescope *aTelescope, const ULong64_t aTimePeriodicty)
	Adds a Telescope in the satellite. More...

double	GetAlphaFromFlightSequence (const double aTime)
	Returns the satellite \(\alpha\) angle at a given time following the flight sequence. More...

double	GetBetaFromFlightSequence (const double aTime)
	Returns the satellite \(\beta\) angle at a given time according the flight sequence. More...

double	GetGammaFromFlightSequence (const double aTime)
	Returns the satellite \(\gamma\) angle at a given time according the flight sequence. More...

string	GetName (void)
	Returns the satellite name. More...

UInt_t	GetTimeResolution (void)
	Returns the satellite time resolution [ms]. More...

void	RunSequence (const ULong64_t aTimeStart, const UInt_t aTimeDuration)
	Runs a simulation sequence. More...

bool	SetFileDuration (const UInt_t aFileDuration)
	Sets the satellite file duration [ms]. More...

void	SetFlightSequence (TGraph aAlpha, TGraph aBeta, TGraph *aGamma)
	Sets the satellite flight sequence. More...

void	SetName (const string aName)
	Sets the satellite name. More...

void	SetOutputDirectory (const string aOutputDirectory)
	Sets the satellite output directory. More...

void	SetTimeResolution (const UInt_t aTimeResolution)
	Sets the satellite time resolution [ms]. More...

Constructors and destructors
	Satellite (const UInt_t aTimeResolution)
	Satellite class constuctor. More...

virtual	~Satellite (void)
	Satellite class destructor. More...

Private Attributes
TGraph *	sat_alpha_seq
	Satellite flight sequence \(\alpha\). More...

TGraph *	sat_beta_seq
	Satellite flight sequence \(\beta\). More...

UInt_t	sat_dt
	Satelitte dt [ms]. More...

UInt_t	sat_filedt
	Satelitte file duration [ms]. More...

TGraph *	sat_gamma_seq
	Satellite flight sequence \(\gamma\). More...

string	sat_name
	Satellite name. More...

string	sat_outdir
	Satellite output directory. More...

vector< Telescope * >	sat_tel
	Vector of telescopes. More...

vector< ULong64_t >	sat_tel_T
	Vector of telescope periodicity. More...

Detailed Description

Satellite control.

This class is designed to generate a satellite observation sequence.

Configuring a satellite

Angular position

The Satellite object must be given a flight sequence with SetFlightSequence(). The flight sequence programs the angular position as a function of time. The three Euler angles, \((\alpha,\beta,\gamma)\), are used to define the satellite angular position in the Earth reference frame, using celestial coordinates \((x',y',z')\). The \(z'\) axis is the rotation axis of the Earth, the \(x'y'\) plane is the equatorial plane, and the \(x'\) axis points to the vernal equinox.

The satellite reference frame is given by a three-dimensional rotation with respect to Earth-based coordinates. Internally, the satellite orientation is controlled using the Euler angles \((\alpha, \beta, \gamma)\). The satellite reference frame is \((x,y,z)\). The x-axis is used as the main-axis for on-board instruments.

In the following figure, the geometrical definitions are represented. The Earth celestial coordinate system \((x',y',z')\) is represented in black. The satellite reference frame \((x,y,z)\) is represented in blue.

Satellite (blue) and Earth celestial (black) reference frame. The rotation to change the system of coordinates is given by the Euler angles and is represented in green.

Timing

The Satellite object must be given a time resolution with SetTimeResolution() which defines the internal clock. The choice of this parameter is crucial as it drives the satellite telescopes in the sequence. When adding a telescope to a satellite, a time periodicity to take pictures should be given. The satellite time resolution must be chosen such that it is the greatest comon divisor of all telescope time periodicities. For example, if you have two telescopes which are programmed to take pictures every 100 ms and 60 ms respectively, you should use a satellite time resolution of 20 ms. See AddTelescope().

In addition another time scale should be defined to tell when the sequence should be saved in files periodically. Again, the satellite time resolution should be a sub-multiple of this periodicity.

Telescopes

A satellite must be equipped with telescopes. Telescope objects must be created and configured first. They are then mounted on the satellite with AddTelescope(). The telescope and the satellite share the same system of corrdinates: the telescope \(x\)-axis is aligned with the satellite \(x\)-axis.

Output files

When running an observation sequence (see below), the data is saved in output ROOT files. The duration for these files must be set with SetFileDuration().

See also: The SatAndLight file structure for satellite objects.

Run an observation sequence

Once the satellite is configured, run an observation sequence with RunSequence(). This function manages the satellite angular position as a function of time and automatically controls on-board telescopes in a synchronized way.

The observation sequence is saved in a sequence of root files.

Author: Florent Robinet

Constructor & Destructor Documentation

◆ Satellite()

Satellite::Satellite ( const UInt_t aTimeResolution )

Satellite class constuctor.

The Satellite object is initialized:

It is given a default name "SAT" (see also SetName()).
The satellite time resolution is set by the user (see also SetTimeResolution()).
The satellite file duration is set to 100 times the satellite time resolution (see also SetFileDuration()).
The output directory is set to the current directory (see also SetOutputDirectory()).
The flight sequence is a single angular position such that the satellite axes \((x,y,z)\) are aligned with the Earth axes \((x',y',z')\) (see also SetFlightSequence()).

Warning: The satellite name must be unique if more than one satellite are used in the same time. If needed, use SetName() to update the name.

Parameters

[in] aTimeResolution Satellite time resolution [ms].

◆ ~Satellite()

Satellite::~Satellite ( void )

virtual

Satellite class destructor.

Member Function Documentation

◆ AddTelescope()

bool Satellite::AddTelescope	(	Telescope *	aTelescope,
		const ULong64_t	aTimePeriodicty
	)

Adds a Telescope in the satellite.

The input telescope should be entirely configured before calling this function. Do not change the telescope configuration after it is added to the satellite. A time periodicity should be specified. It tells the satellite when to take a picture. This periodicity should be a multiple of the satellite time resolution previously set with SetTimeResolution().

Parameters

[in]	aTelescope	Pointer to a Telescope object.
[in]	aTimePeriodicty	Time periodicity [ms].

Returns: true if the telescope is properly added to the satellite, false otherwise.

◆ GetAlphaFromFlightSequence()

double Satellite::GetAlphaFromFlightSequence ( const double aTime )

Returns the satellite \(\alpha\) angle at a given time following the flight sequence.

The Euler angle \(\alpha\) is evaluated following the flight sequence set with SetFlightSequence():

1 single point → unique and static value.
the angle value is linearly interpolated.
if the requested time is out-of-range, the last known value is used.
Parameters

[in] aTime Satellite time [ms].

◆ GetBetaFromFlightSequence()

double Satellite::GetBetaFromFlightSequence ( const double aTime )

Returns the satellite \(\beta\) angle at a given time according the flight sequence.

The Euler angle \(\beta\) is evaluated according the flight sequence set with SetFlightSequence():

1 single point → unique and static value.
the angle value is linearly interpolated.
if the requested time is out-of-range, the last known value is used.
Parameters

[in] aTime Satellite time [ms].

◆ GetGammaFromFlightSequence()

double Satellite::GetGammaFromFlightSequence ( const double aTime )

Returns the satellite \(\gamma\) angle at a given time according the flight sequence.

The Euler angle \(\gamma\) is evaluated according the flight sequence set with SetFlightSequence():

1 single point → unique and static value.
the angle value is linearly interpolated.
if the requested time is out-of-range, the last known value is used.
Parameters

[in] aTime Satellite time [ms].

◆ GetName()

string Satellite::GetName ( void )

inline

Returns the satellite name.

◆ GetTimeResolution()

UInt_t Satellite::GetTimeResolution ( void )

inline

Returns the satellite time resolution [ms].

◆ RunSequence()

void Satellite::RunSequence	(	const ULong64_t	aTimeStart,
		const UInt_t	aTimeDuration
	)

Runs a simulation sequence.

The satellite clock is ticking starting at aTimeStart and for a duration aTimeDuration. Each tick is separated by the satellite time resolution set with SetTimeResolution(). When the satellite time matches a telescope periodicity, a picture is taken with Telescope::TakePicture(). During the exposure time, the satellite position is assumed to be static and equal to the scheduled position in the middle of the exposure time.

Parameters

[in]	aTimeStart	Sequence starting time [ms].
[in]	aTimeDuration	Sequence duration [ms].

◆ SetFileDuration()

bool Satellite::SetFileDuration ( const UInt_t aFileDuration )

Sets the satellite file duration [ms].

The file duration parameter tells the satellite when to save the sequence in a file. This parameter should be a multiple of the satellite time resolution previously set with SetTimeResolution().

Parameters

[in] aFileDuration Satellite file duration [ms].

◆ SetFlightSequence()

void Satellite::SetFlightSequence	(	TGraph *	aAlpha,
		TGraph *	aBeta,
		TGraph *	aGamma
	)

Sets the satellite flight sequence.

The satellite Euler angles can be provided using TGraph objects. Each point of the graph gives the angle [rad] as a function of time [ms]. The number of points in the graph does not matter as linear interpolation is used to match the satellite time resolution. If the graph is a single point, it is interpreted as a time-independent value.

Parameters

[in]	aAlpha	Pointer to a TGraph describing \(\alpha\) as a function of time.
[in]	aBeta	Pointer to a TGraph describing \(\beta\) as a function of time.
[in]	aGamma	Pointer to a TGraph describing \(\gamma\) as a function of time.

Precondition: All TGraph pointers are valid pointers to TGraph objects.

Warning: The points in the TGraph MUST be sorted in time!

Note: The input TGraph objects can be deleted after calling this function.

◆ SetName()

void Satellite::SetName ( const string aName )

Sets the satellite name.

The satellite name must be unique if more than one satellite are used in the same time.

Parameters

[in] aName Satellite name.

◆ SetOutputDirectory()

void Satellite::SetOutputDirectory ( const string aOutputDirectory )

inline

Sets the satellite output directory.

Output files will be saved in that directory.

Parameters

[in] aOutputDirectory Path to output directory.

Precondition: The output directory must exist.

◆ SetTimeResolution()

void Satellite::SetTimeResolution ( const UInt_t aTimeResolution )

inline

Sets the satellite time resolution [ms].

Parameters

[in] aTimeResolution Satellite time resolution [ms].

Member Data Documentation

◆ sat_alpha_seq

TGraph* Satellite::sat_alpha_seq

private

Satellite flight sequence \(\alpha\).

◆ sat_beta_seq

TGraph* Satellite::sat_beta_seq

private

Satellite flight sequence \(\beta\).

◆ sat_dt

UInt_t Satellite::sat_dt

private

Satelitte dt [ms].

◆ sat_filedt

UInt_t Satellite::sat_filedt

private

Satelitte file duration [ms].

◆ sat_gamma_seq

TGraph* Satellite::sat_gamma_seq

private

Satellite flight sequence \(\gamma\).

◆ sat_name

string Satellite::sat_name

private

Satellite name.

◆ sat_outdir

string Satellite::sat_outdir

private

Satellite output directory.

◆ sat_tel

vector<Telescope*> Satellite::sat_tel

private

Vector of telescopes.

◆ sat_tel_T

vector<ULong64_t> Satellite::sat_tel_T

private

Vector of telescope periodicity.

The documentation for this class was generated from the following files:

src/Satellite/Satellite.h
src/Satellite/Satellite.cc

Public Member Functions

Private Attributes

Detailed Description

Configuring a satellite

Angular position

Timing

Telescopes

Output files

Run an observation sequence

Constructor & Destructor Documentation

◆ Satellite()

◆ ~Satellite()

Member Function Documentation

◆ AddTelescope()

◆ GetAlphaFromFlightSequence()

◆ GetBetaFromFlightSequence()

◆ GetGammaFromFlightSequence()

◆ GetName()

◆ GetTimeResolution()

◆ RunSequence()

◆ SetFileDuration()

◆ SetFlightSequence()

◆ SetName()

◆ SetOutputDirectory()

◆ SetTimeResolution()

Member Data Documentation

◆ sat_alpha_seq

◆ sat_beta_seq

◆ sat_dt

◆ sat_filedt

◆ sat_gamma_seq

◆ sat_name

◆ sat_outdir

◆ sat_tel

◆ sat_tel_T