org.orekit.models.earth.ionosphere

Class GlobalIonosphereMapModel

java.lang.Object

org.orekit.models.earth.ionosphere.GlobalIonosphereMapModel

All Implemented Interfaces:

Serializable, IonosphericModel

public class GlobalIonosphereMapModel
extends Object
implements IonosphericModel

Global Ionosphere Map (GIM) model. The ionospheric delay is computed according to the formulas:

           40.3
    δ =  --------  *  STEC      with, STEC = VTEC * F(elevation)
            f²
 

With:

• f: The frequency of the signal in Hz.
• STEC: The Slant Total Electron Content in TECUnits.
• VTEC: The Vertical Total Electron Content in TECUnits.
• F(elevation): A mapping function which depends on satellite elevation.

The VTEC is read from a IONEX file. A stream contains, for a given day, the values of the TEC for each hour of the day. Values are given on a global 2.5° x 5.0° (latitude x longitude) grid.

A bilinear interpolation is performed the case of the user initialize the latitude and the longitude with values that are not contained in the stream.

A temporal interpolation is also performed to compute the VTEC at the desired date.

IONEX files are obtained from The Crustal Dynamics Data Information System.

The files have to be extracted to UTF-8 text files before being read by this loader.

Example of file:

      1.0            IONOSPHERE MAPS     GPS                 IONEX VERSION / TYPE
 BIMINX V5.3         AIUB                16-JAN-19 07:26     PGM / RUN BY / DATE
 BROADCAST IONOSPHERE MODEL FOR DAY 015, 2019                COMMENT
   2019     1    15     0     0     0                        EPOCH OF FIRST MAP
   2019     1    16     0     0     0                        EPOCH OF LAST MAP
   3600                                                      INTERVAL
     25                                                      # OF MAPS IN FILE
   NONE                                                      MAPPING FUNCTION
      0.0                                                    ELEVATION CUTOFF
                                                             OBSERVABLES USED
   6371.0                                                    BASE RADIUS
      2                                                      MAP DIMENSION
    350.0 350.0   0.0                                        HGT1 / HGT2 / DHGT
     87.5 -87.5  -2.5                                        LAT1 / LAT2 / DLAT
   -180.0 180.0   5.0                                        LON1 / LON2 / DLON
     -1                                                      EXPONENT
 TEC/RMS values in 0.1 TECU; 9999, if no value available     COMMENT
                                                             END OF HEADER
      1                                                      START OF TEC MAP
   2019     1    15     0     0     0                        EPOCH OF CURRENT MAP
     87.5-180.0 180.0   5.0 350.0                            LAT/LON1/LON2/DLON/H
    92   92   92   92   92   92   92   92   92   92   92   92   92   92   92   92
    92   92   92   92   92   92   92   92   92   92   92   92   92   92   92   92
    92   92   92   92   92   92   92   92   92   92   92   92   92   92   92   92
    92   92   92   92   92   92   92   92   92   92   92   92   92   92   92   92
    92   92   92   92   92   92   92   92   92
    ...
 

Author:

Bryan Cazabonne

See Also:

"Schaer, S., W. Gurtner, and J. Feltens, 1998, IONEX: The IONosphere Map EXchange Format Version 1, February 25, 1998, Proceedings of the IGS AC Workshop Darmstadt, Germany, February 9–11, 1998", Serialized Form

Constructor Summary

Constructors

Constructor and Description
GlobalIonosphereMapModel(String supportedNames) Constructor with supported names given by user.

Method Summary

Modifier and Type	Method and Description
List<ParameterDriver>	getParametersDrivers() Get the drivers for ionospheric model parameters.
double	getTEC(AbsoluteDate date, GeodeticPoint recPoint) Computes the Total Electron Content (TEC) at a given date by performing a temporal interpolation with the two closest date in the IONEX file.
<T extends RealFieldElement<T>> T	getTEC(FieldAbsoluteDate<T> date, GeodeticPoint recPoint) Computes the Total Electron Content (TEC) at a given date by performing a temporal interpolation with the two closest date in the IONEX file.
double	pathDelay(AbsoluteDate date, GeodeticPoint geo, double elevation, double frequency) Calculates the ionospheric path delay for the signal path from a ground station to a satellite.
<T extends RealFieldElement<T>> T	pathDelay(FieldAbsoluteDate<T> date, GeodeticPoint geo, T elevation, double frequency) Calculates the ionospheric path delay for the signal path from a ground station to a satellite.
<T extends RealFieldElement<T>> T	pathDelay(FieldSpacecraftState<T> state, TopocentricFrame baseFrame, double frequency, T[] parameters) Calculates the ionospheric path delay for the signal path from a ground station to a satellite.
double	pathDelay(SpacecraftState state, TopocentricFrame baseFrame, double frequency, double[] parameters) Calculates the ionospheric path delay for the signal path from a ground station to a satellite.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.models.earth.ionosphere.IonosphericModel

getParameters, getParameters

Constructor Detail

GlobalIonosphereMapModel

public GlobalIonosphereMapModel(String supportedNames)

Constructor with supported names given by user.

Parameters:

supportedNames - supported name

Method Detail

pathDelay

public double pathDelay(AbsoluteDate date,
                        GeodeticPoint geo,
                        double elevation,
                        double frequency)

Calculates the ionospheric path delay for the signal path from a ground station to a satellite.

The path delay can be computed for any elevation angle.

Parameters:

date - current date

geo - geodetic point of receiver/station

elevation - elevation of the satellite in radians

frequency - frequency of the signal in Hz

Returns:

the path delay due to the ionosphere in m

pathDelay

public double pathDelay(SpacecraftState state,
                        TopocentricFrame baseFrame,
                        double frequency,
                        double[] parameters)

Description copied from interface: IonosphericModel

Calculates the ionospheric path delay for the signal path from a ground station to a satellite.

This method is intended to be used for orbit determination issues. In that respect, if the elevation is below 0° the path delay will be equal to zero.

For individual use of the ionospheric model (i.e. not for orbit determination), another method signature can be implemented to compute the path delay for any elevation angle.

Specified by:

pathDelay in interface IonosphericModel

Parameters:

state - spacecraft state

baseFrame - base frame associated with the station

frequency - frequency of the signal in Hz

parameters - ionospheric model parameters

Returns:

the path delay due to the ionosphere in m

pathDelay

public <T extends RealFieldElement<T>> T pathDelay(FieldAbsoluteDate<T> date,
                                                   GeodeticPoint geo,
                                                   T elevation,
                                                   double frequency)

Calculates the ionospheric path delay for the signal path from a ground station to a satellite.

The path delay can be computed for any elevation angle.

Type Parameters:

T - type of the elements

Parameters:

date - current date

geo - geodetic point of receiver/station

elevation - elevation of the satellite in radians

frequency - frequency of the signal in Hz

Returns:

the path delay due to the ionosphere in m

pathDelay

public <T extends RealFieldElement<T>> T pathDelay(FieldSpacecraftState<T> state,
                                                   TopocentricFrame baseFrame,
                                                   double frequency,
                                                   T[] parameters)

Description copied from interface: IonosphericModel

Calculates the ionospheric path delay for the signal path from a ground station to a satellite.

This method is intended to be used for orbit determination issues. In that respect, if the elevation is below 0° the path delay will be equal to zero.

For individual use of the ionospheric model (i.e. not for orbit determination), another method signature can be implemented to compute the path delay for any elevation angle.

Specified by:

pathDelay in interface IonosphericModel

Type Parameters:

T - type of the elements

Parameters:

state - spacecraft state

baseFrame - base frame associated with the station

frequency - frequency of the signal in Hz

parameters - ionospheric model parameters

Returns:

the path delay due to the ionosphere in m

getTEC

public double getTEC(AbsoluteDate date,
                     GeodeticPoint recPoint)

Computes the Total Electron Content (TEC) at a given date by performing a temporal interpolation with the two closest date in the IONEX file.

Parameters:

date - current date

recPoint - geodetic point of receiver/station

Returns:

the TEC after a temporal interpolation, in TECUnits

getTEC

public <T extends RealFieldElement<T>> T getTEC(FieldAbsoluteDate<T> date,
                                                GeodeticPoint recPoint)

Computes the Total Electron Content (TEC) at a given date by performing a temporal interpolation with the two closest date in the IONEX file.

Type Parameters:

T - type of the elements

Parameters:

date - current date

recPoint - geodetic point of receiver/station

Returns:

the TEC after a temporal interpolation, in TECUnits

getParametersDrivers

public List<ParameterDriver> getParametersDrivers()

Description copied from interface: IonosphericModel

Get the drivers for ionospheric model parameters.

Specified by:

getParametersDrivers in interface IonosphericModel

Returns:

drivers for ionospheric model parameters