Package org.orekit.models.earth

Class SaastamoinenModel

java.lang.Object

org.orekit.models.earth.SaastamoinenModel

All Implemented Interfaces:

Serializable, DiscreteTroposphericModel, MappingFunction, TroposphericModel

public class SaastamoinenModel
extends Object
implements TroposphericModel

The modified Saastamoinen model. Estimates the path delay imposed to electro-magnetic signals by the troposphere according to the formula:

 δ = 2.277e-3 / cos z * (P + (1255 / T + 0.05) * e - B * tan²
 z) + δR
 

with the following input data provided to the model:

• z: zenith angle
• P: atmospheric pressure
• T: temperature
• e: partial pressure of water vapour
• B, δR: correction terms

The model supports custom δR correction terms to be read from a configuration file (saastamoinen-correction.txt) via the DataProvidersManager.

Author:

Thomas Neidhart

See Also:

"Guochang Xu, GPS - Theory, Algorithms and Applications, Springer, 2007", Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static String	DELTA_R_FILE_NAME	Default file name for δR correction term table.

Constructor Summary

Constructors

Constructor	Description
SaastamoinenModel(double t0, double p0, double r0, String deltaRFileName)	Create a new Saastamoinen model for the troposphere using the given environmental conditions.

Method Summary

Modifier and Type	Method	Description
static SaastamoinenModel	getStandardModel()	Create a new Saastamoinen model using a standard atmosphere model.
double	pathDelay(double elevation, double height)	Calculates the tropospheric path delay for the signal path from a ground station to a satellite.

Methods inherited from interface org.orekit.models.earth.MappingFunction

getParameters, getParameters

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.TroposphericModel

computeZenithDelay, computeZenithDelay, getParametersDrivers, mappingFactors, mappingFactors, pathDelay, pathDelay, pathDelay

Field Detail

DELTA_R_FILE_NAME

public static final String DELTA_R_FILE_NAME

Default file name for δR correction term table.

See Also:

Constant Field Values

Constructor Detail

SaastamoinenModel

public SaastamoinenModel(double t0,
                         double p0,
                         double r0,
                         String deltaRFileName)

Create a new Saastamoinen model for the troposphere using the given environmental conditions.

Parameters:

t0 - the temperature at the station [K]

p0 - the atmospheric pressure at the station [mbar]

r0 - the humidity at the station [fraction] (50% -> 0.5)

deltaRFileName - regular expression for filename containing δR correction term table (typically DELTA_R_FILE_NAME), if null default values from the reference book are used

Since:

7.1

Method Detail

getStandardModel

public static SaastamoinenModel getStandardModel()

Create a new Saastamoinen model using a standard atmosphere model.

• temperature: 18 degree Celsius
• pressure: 1013.25 mbar
• humidity: 50%

Returns:

a Saastamoinen model with standard environmental values

pathDelay

public double pathDelay(double elevation,
                        double height)

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

The Saastamoinen model is not defined for altitudes below 0.0. for continuity reasons, we use the value for h = 0 when altitude is negative.

Specified by:

pathDelay in interface TroposphericModel

Parameters:

elevation - the elevation of the satellite, in radians

height - the height of the station in m above sea level

Returns:

the path delay due to the troposphere in m