org.orekit.models.earth
Class SaastamoinenModel

java.lang.Object
  org.orekit.models.earth.SaastamoinenModel

public class SaastamoinenModel
extends Object

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"

Constructor Summary

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

Method Summary

double	calculatePathDelay(double elevation, double height) Calculates the tropospheric path delay for the signal path from a ground station to a satellite.
double	computeSignalDelay(double elevation, double height) Calculates the tropospheric signal delay for the signal path from a ground station to a satellite.
static SaastamoinenModel	getStandardModel() Create a new Saastamoinen model using a standard atmosphere model.

Methods inherited from class java.lang.Object

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

Constructor Detail

SaastamoinenModel

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

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 [Pa]

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

Method Detail

getStandardModel

public static SaastamoinenModel getStandardModel()

Create a new Saastamoinen model using a standard atmosphere model.

• temperature: 18 degree Celsius
• pressure: 101325 Pa
• humidity: 50%

Returns:

a Saastamoinen model with standard environmental values

calculatePathDelay

public double calculatePathDelay(double elevation,
                                 double height)

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

Parameters:

elevation - the elevation of the satellite in degrees

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

Returns:

the path delay due to the troposphere in m

computeSignalDelay

public double computeSignalDelay(double elevation,
                                 double height)

Calculates the tropospheric signal delay for the signal path from a ground station to a satellite. This method exists only for convenience reasons and returns the same as

   calculatePathDelay(double, double)/Constants.SPEED_OF_LIGHT
 

Parameters:

elevation - the elevation of the satellite in degrees

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

Returns:

the signal delay due to the troposphere in s