fr.cnes.sirius.patrius.signalpropagation.troposphere

Class AstronomicalRefractionModel

java.lang.Object

fr.cnes.sirius.patrius.signalpropagation.troposphere.AstronomicalRefractionModel

All Implemented Interfaces:

IParameterizable, AngularCorrection, FiniteDistanceAngularCorrection, Serializable

public class AstronomicalRefractionModel
extends Object
implements FiniteDistanceAngularCorrection

This class represent a tropospheric refraction model. It is directly extracted from [1].

This class uses interpolation tables. Be aware that it accepts extrapolation of these table to some extent. When the extrapolation is likely to go too far compared to the table resolution, a verification is done. This is the case for the maximum zenithal distance and the wavelength of the signal. For the other values, no check is performed.

Source: [1] "Introduction aux ephemerides astronomiques" Bureau des longitudes, edition 1997"

All private methods will use the units of the source (which are often not SI) to keep as close as possible to the book formulas. All public methods will use international units.

Since:

4.13

Author:

veuillh, amouroum

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAX_ITER Default max iteration number for the iterative algorithm used to compute the elevation correction from geometric elevation.
static double	DEFAULT_THRESHOLD Default threshold value for the iterative algorithm used to compute the elevation correction from geometric elevation [rad].

Constructor Summary

Constructors

Constructor and Description
AstronomicalRefractionModel(BodyPoint point, MeteorologicalConditionsProvider meteoConditionsProvider, double wavelengthNanometer) Simple constructor.
AstronomicalRefractionModel(BodyPoint point, MeteorologicalConditionsProvider meteoConditionsProvider, double wavelengthNanometer, double threshold, int maxIter) Main constructor.

Method Summary

Modifier and Type	Method and Description
double	computeElevationCorrectionFromApparentElevation(AbsoluteDate date, double apparentElevation, double distance) Compute the tropospheric correction from the apparent elevation and distance.
static double	computeElevationCorrectionFromApparentElevation(double apparentElevation, double pressure, double temperature, double relativeHumidity, double wavelengthNanometer, double latitude, double altitude, double distance) Compute the tropospheric correction from the apparent elevation and the provided conditions.
double	computeElevationCorrectionFromGeometricElevation(AbsoluteDate date, double geometricElevation, double distance) Compute the tropospheric correction from the geometric elevation and distance.
static double	computeElevationCorrectionFromGeometricElevation(double geometricElevation, double pressure, double temperature, double relativeHumidity, double wavelengthNanometer, double latitude, double altitude, double distance, double threshold, int maxIter) Compute the tropospheric correction from the geometric elevation and the provided conditions.
static double	computeGroundRefractivity(double apparentElevation, double pressure, double temperature) Compute the ground refractivity by taking into account elevation, pressure and temperature.
static double	computeOOPrime(double groundRefractivity, double elevationCorrection, double apparentElevation) Compute the OO' distance.
static double	computeParallaxCorrection(double geometricElevation, double oOPrime, double distance) Compute the parallax correction due to a finite distance object.
double	derivativeValueFromApparentElevation(Parameter p, double elevation) Compute the elevation correction derivative value with respect to the input parameter.
double	derivativeValueFromGeometricElevation(Parameter p, double geometricElevation) Compute the elevation correction derivative value with respect to the input parameter.
static double	elevationToZenithalDistance(double elevation) Convert elevation to zenithal distance [rad].
int	getMaxIter() Getter for the maximum iteration number used in the convergence algorithm to compute the correction from the geometric elevation.
MeteorologicalConditionsProvider	getMeteoConditionsProvider() Getter for the meteo conditions provider.
double	getMinimalToleratedApparentElevation() Getter for the minimal tolerated apparent elevation for this model (some models cannot compute correction for too low elevations).
ArrayList<Parameter>	getParameters() Get the supported parameters.
BodyPoint	getPoint() Getter for the position where the model should be applied.
double	getThreshold() Getter for the threshold used in the convergence algorithm to compute the correction from the geometric elevation.
double	getWavelengthNanometer() Getter for the wavelength [nanometer].
boolean	isDifferentiableBy(Parameter p) Tell if the function is differentiable by the given parameter.
boolean	supportsParameter(Parameter param) Check if a parameter is supported.
static double	zenithalDistanceToElevation(double zenithalDistance) Convert zenithal distance to elevation [rad].

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface fr.cnes.sirius.patrius.signalpropagation.FiniteDistanceAngularCorrection

computeElevationCorrectionFromApparentElevation, computeElevationCorrectionFromGeometricElevation

Field Detail

DEFAULT_THRESHOLD

public static final double DEFAULT_THRESHOLD

Default threshold value for the iterative algorithm used to compute the elevation correction from geometric elevation [rad].
Justification: This tropospheric model is essentially used for Astrometric TAROT measurements. The precision of these measurements is currently around 1e-6 rad. It is safe to take 2 orders of magnitude lower than this precision.

See Also:

Constant Field Values

DEFAULT_MAX_ITER

public static final int DEFAULT_MAX_ITER

Default max iteration number for the iterative algorithm used to compute the elevation correction from geometric elevation.

See Also:

Constant Field Values

Constructor Detail

AstronomicalRefractionModel

public AstronomicalRefractionModel(BodyPoint point,
                                   MeteorologicalConditionsProvider meteoConditionsProvider,
                                   double wavelengthNanometer)

Simple constructor.
The tropospheric correction is applied to the geometric elevation, and the use of values outside the tables throws an exception.

Parameters:

point - The geodetic point of the ground station

meteoConditionsProvider - The meteorological condition provider at the ground station

wavelengthNanometer - The wavelength of the signal [nanometer]

Throws:

IllegalArgumentException - if the provided wavelength is outside the tolerated wavelength bound for tables linear extrapolations

AstronomicalRefractionModel

public AstronomicalRefractionModel(BodyPoint point,
                                   MeteorologicalConditionsProvider meteoConditionsProvider,
                                   double wavelengthNanometer,
                                   double threshold,
                                   int maxIter)

Main constructor.
The use of values outside the tables throws an exception.

Parameters:

point - The geodetic point of the ground station

meteoConditionsProvider - The meteorological condition provider at the ground station

wavelengthNanometer - The wavelength of the signal [nanometer]

threshold - Threshold for the iterative algorithm used to compute the elevation correction from geometric elevation [rad]

maxIter - Max iteration number for the iterative algorithm used to compute the elevation correction from geometric elevation

Throws:

IllegalArgumentException - if the provided wavelength is outside the tolerated wavelength bound for tables linear extrapolations

Method Detail

isDifferentiableBy

public boolean isDifferentiableBy(Parameter p)

Tell if the function is differentiable by the given parameter.

Specified by:

isDifferentiableBy in interface AngularCorrection

Parameters:

p - Parameter

Returns:

true if the function is differentiable by the given parameter

supportsParameter

public boolean supportsParameter(Parameter param)

Check if a parameter is supported.

Specified by:

supportsParameter in interface IParameterizable

Parameters:

param - parameter to check

Returns:

true if the parameter is supported

getParameters

public ArrayList<Parameter> getParameters()

Get the supported parameters.

Specified by:

getParameters in interface IParameterizable

Returns:

list of supported parameters

derivativeValueFromGeometricElevation

public double derivativeValueFromGeometricElevation(Parameter p,
                                                    double geometricElevation)

Compute the elevation correction derivative value with respect to the input parameter.

Specified by:

derivativeValueFromGeometricElevation in interface AngularCorrection

Parameters:

p - Parameter

geometricElevation - The geometric elevation (without atmosphere) of the satellite [rad]

Returns:

the elevation derivative value

derivativeValueFromApparentElevation

public double derivativeValueFromApparentElevation(Parameter p,
                                                   double elevation)

Compute the elevation correction derivative value with respect to the input parameter.

Specified by:

derivativeValueFromApparentElevation in interface AngularCorrection

Parameters:

p - Parameter

elevation - The apparent elevation (with atmosphere) of the satellite [rad]

Returns:

the elevation derivative value

computeElevationCorrectionFromApparentElevation

public double computeElevationCorrectionFromApparentElevation(AbsoluteDate date,
                                                              double apparentElevation,
                                                              double distance)

Compute the tropospheric correction from the apparent elevation and distance.

This method takes into account the finite distance of the observed object to add a parallax correction.

Specified by:

computeElevationCorrectionFromApparentElevation in interface FiniteDistanceAngularCorrection

Parameters:

date - The date at which we want to compute the tropospheric correction

apparentElevation - The apparent elevation (with atmosphere) [rad]

distance - The distance to the object [m]. Can be Double.POSITIVE_INFINITY (equivalent to not take into account the parallax correction)

Returns:

the elevation correction [rad] so that : apparent_elevation = geometric_elevation + elevation_correction

computeElevationCorrectionFromGeometricElevation

public double computeElevationCorrectionFromGeometricElevation(AbsoluteDate date,
                                                               double geometricElevation,
                                                               double distance)

Compute the tropospheric correction from the geometric elevation and distance.

Note that this method uses an iterative algorithm to convert the geometric elevation into an apparent elevation. Note that if the convergence is not reached within the getMaxIter(), no exception is thrown.

This method takes into account the finite distance of the observed object to add a parallax correction.

Specified by:

computeElevationCorrectionFromGeometricElevation in interface FiniteDistanceAngularCorrection

Parameters:

date - The date at which we want to compute the tropospheric correction

geometricElevation - The geometric elevation (without atmosphere) [rad]

distance - The distance to the object [m]. Can be Double.POSITIVE_INFINITY (equivalent to not take into account the parallax correction).

Returns:

the elevation correction [rad] so that : apparent_elevation = geometric_elevation + elevation_correction

getMinimalToleratedApparentElevation

public double getMinimalToleratedApparentElevation()

Getter for the minimal tolerated apparent elevation for this model (some models cannot compute correction for too low elevations).

Specified by:

getMinimalToleratedApparentElevation in interface AngularCorrection

Returns:

the minimal tolerated apparent elevation [rad]

getMeteoConditionsProvider

public MeteorologicalConditionsProvider getMeteoConditionsProvider()

Getter for the meteo conditions provider.

Returns:

the meteo conditions provider

getWavelengthNanometer

public double getWavelengthNanometer()

Getter for the wavelength [nanometer].

Returns:

the wavelength

getPoint

public BodyPoint getPoint()

Getter for the position where the model should be applied.

Returns:

the point where the model should be applied

getThreshold

public double getThreshold()

Getter for the threshold used in the convergence algorithm to compute the correction from the geometric elevation.

Returns:

the threshold [rad]

getMaxIter

public int getMaxIter()

Getter for the maximum iteration number used in the convergence algorithm to compute the correction from the geometric elevation.

Note that if the convergence is not reached within this max iteration number, no exception is thrown.

Returns:

the maximum iteration number

computeGroundRefractivity

public static double computeGroundRefractivity(double apparentElevation,
                                               double pressure,
                                               double temperature)

Compute the ground refractivity by taking into account elevation, pressure and temperature.

See [1] p. 194 Equation (7.3.9)

Parameters:

apparentElevation - The apparent elevation (with atmosphere) [rad]

pressure - The pressure [Pa]

temperature - The temperature [K°]

Returns:

the ground refraction [dimensionless]

computeOOPrime

public static double computeOOPrime(double groundRefractivity,
                                    double elevationCorrection,
                                    double apparentElevation)

Compute the OO' distance.

This distance aims at computing a parallax effect for the elevation correction at finite distance.

See [1] p.203 Equation (7.3.19)

Parameters:

groundRefractivity - The ground refractivity [dimensionless]

elevationCorrection - The apparent elevation correction for an object at an infinite distance [rad]

apparentElevation - Apparent elevation (with atmosphere) (for an object at infinite distance) [rad]

Returns:

the distance OO' [m]

computeParallaxCorrection

public static double computeParallaxCorrection(double geometricElevation,
                                               double oOPrime,
                                               double distance)

Compute the parallax correction due to a finite distance object.

Parameters:

geometricElevation - The geometric elevation (without atmosphere) (for an object at infinite distance) [rad]

oOPrime - The fictive distance to compute the parallax [m]

distance - The distance to the object [m]

Returns:

the parallax correction so that : elevationFiniteDistance = elevationInfiniteDistance + parallax

elevationToZenithalDistance

public static double elevationToZenithalDistance(double elevation)

Convert elevation to zenithal distance [rad].

Parameters:

elevation - The elevation [rad]

Returns:

the zenithal distance

zenithalDistanceToElevation

public static double zenithalDistanceToElevation(double zenithalDistance)

Convert zenithal distance to elevation [rad].

Parameters:

zenithalDistance - The zenithal distance [rad]

Returns:

the elevation

computeElevationCorrectionFromApparentElevation

public static double computeElevationCorrectionFromApparentElevation(double apparentElevation,
                                                                     double pressure,
                                                                     double temperature,
                                                                     double relativeHumidity,
                                                                     double wavelengthNanometer,
                                                                     double latitude,
                                                                     double altitude,
                                                                     double distance)

Compute the tropospheric correction from the apparent elevation and the provided conditions.

This method takes into account the finite distance of the observed object to add a parallax correction.

Parameters:

apparentElevation - The apparent elevation [rad]

pressure - The pressure [Pa]

temperature - The temperature [K°]

relativeHumidity - The relative humidity (from 0 to 100) [%]

wavelengthNanometer - The wavelength [nanometer]

latitude - The latitude [rad]

altitude - The altitude [m]

distance - The distance of the observed object [m]. Can be Double.POSITIVE_INFINITY (equivalent to not take into account the parallax correction).

Returns:

the elevation correction [rad] so that : apparentElevation = geometricElevation + elevationCorrection

Throws:

IllegalArgumentException - if the apparent zenithal distance is greater than the maximum apparent zenithal distance allowed for tables linear extrapolations
if the provided wavelength is outside the tolerated wavelength bound for tables linear extrapolations

computeElevationCorrectionFromGeometricElevation

public static double computeElevationCorrectionFromGeometricElevation(double geometricElevation,
                                                                      double pressure,
                                                                      double temperature,
                                                                      double relativeHumidity,
                                                                      double wavelengthNanometer,
                                                                      double latitude,
                                                                      double altitude,
                                                                      double distance,
                                                                      double threshold,
                                                                      int maxIter)

Compute the tropospheric correction from the geometric elevation and the provided conditions.

The input is the geometric elevation while the model takes the apparent elevation as an input. An iterative algorithm (fix point) is used to call the model with the apparent elevation, hence the threshold and maxIter arguments. Note that if the convergence is not reached within the maxIter, no exception is thrown.

This method takes into account the finite distance of the observed object to add a parallax correction.

Parameters:

geometricElevation - The geometric elevation [rad]

pressure - The pressure [Pa]

temperature - The temperature [K°]

relativeHumidity - The relative humidity (from 0 to 100) [%]

wavelengthNanometer - The wavelength [nanometer]

latitude - The latitude [rad]

altitude - The altitude [m]

distance - The distance of the observed object [m]. Can be Double.POSITIVE_INFINITY (equivalent to not take into account the parallax correction).

threshold - Threshold for the iterative algorithm [rad]

maxIter - Max iteration number

Returns:

the geometric elevation [rad]