org.orekit.models.earth

Class SaastamoinenModel

java.lang.Object

org.orekit.models.earth.SaastamoinenModel

All Implemented Interfaces:

Serializable, 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 and Description
static String	DELTA_R_FILE_NAME Default file name for δR correction term table.

Constructor Summary

Constructors

Constructor and 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 and 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 class java.lang.Object

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

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)
                  throws OrekitException

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

Throws:

OrekitException - if δR correction term table cannot be loaded

Since:

7.1

Method Detail

getStandardModel

public static SaastamoinenModel getStandardModel()
                                          throws OrekitException

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

Throws:

OrekitException - if δR correction term table cannot be loaded

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