Package org.orekit.models.earth.ionosphere

Class KlobucharIonoModel

  • All Implemented Interfaces:
    IonosphericModel, ParameterDriversProvider
    public class KlobucharIonoModel
extends Object
implements IonosphericModel
    Klobuchar ionospheric delay model. Klobuchar ionospheric delay model is designed as a GNSS correction model. The parameters for the model are provided by the GPS satellites in their broadcast messsage. This model is based on the assumption the electron content is concentrated in 350 km layer. The delay refers to L1 (1575.42 MHz). If the delay is sought for L2 (1227.60 MHz), multiply the result by 1.65 (Klobuchar, 1996). More generally, since ionospheric delay is inversely proportional to the square of the signal frequency f, to adapt this model to other GNSS frequencies f, multiply by (L1 / f)^2. References: ICD-GPS-200, Rev. C, (1997), pp. 125-128 Klobuchar, J.A., Ionospheric time-delay algorithm for single-frequency GPS users, IEEE Transactions on Aerospace and Electronic Systems, Vol. 23, No. 3, May 1987 Klobuchar, J.A., "Ionospheric Effects on GPS", Global Positioning System: Theory and Applications, 1996, pp.513-514, Parkinson, Spilker.
    Since:
    7.1
    Author:
    Joris Olympio

    • Constructor Detail

      • KlobucharIonoModel

        @DefaultDataContext
public KlobucharIonoModel​(double[] alpha,
                          double[] beta)
        Create a new Klobuchar ionospheric delay model, when a single frequency system is used. This model accounts for at least 50 percent of RMS error due to ionospheric propagation effect (ICD-GPS-200)

        This constructor uses the default data context.

        Parameters:
        alpha - coefficients of a cubic equation representing the amplitude of the vertical delay.
        beta - coefficients of a cubic equation representing the period of the model.
        See Also:
        KlobucharIonoModel(double[], double[], TimeScale)

      • KlobucharIonoModel

        public KlobucharIonoModel​(double[] alpha,
                          double[] beta,
                          TimeScale gps)
        Create a new Klobuchar ionospheric delay model, when a single frequency system is used. This model accounts for at least 50 percent of RMS error due to ionospheric propagation effect (ICD-GPS-200)
        Parameters:
        alpha - coefficients of a cubic equation representing the amplitude of the vertical delay.
        beta - coefficients of a cubic equation representing the period of the model.
        gps - GPS time scale.
        Since:
        10.1

    • Method Detail

      • pathDelay

        public double pathDelay​(AbsoluteDate date,
                        GeodeticPoint geo,
                        double elevation,
                        double azimuth,
                        double frequency,
                        double[] parameters)
        Calculates the ionospheric path delay for the signal path from a ground station to a satellite.

        The path delay is computed for any elevation angle.

        Parameters:
        date - current date
        geo - geodetic point of receiver/station
        elevation - elevation of the satellite in radians
        azimuth - azimuth of the satellite in radians
        frequency - frequency of the signal in Hz
        parameters - ionospheric model parameters
        Returns:
        the path delay due to the ionosphere in m

      • pathDelay

        public 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.

        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 at state date
        Returns:
        the path delay due to the ionosphere in m

      • pathDelay

        public <T extends CalculusFieldElement<T>> T pathDelay​(FieldAbsoluteDate<T> date,
                                                       FieldGeodeticPoint<T> geo,
                                                       T elevation,
                                                       T azimuth,
                                                       double frequency,
                                                       T[] parameters)
        Calculates the ionospheric path delay for the signal path from a ground station to a satellite.

        The path delay is 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
        azimuth - azimuth of the satellite in radians
        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 CalculusFieldElement<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.

        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 at state date
        Returns:
        the path delay due to the ionosphere in m