java.lang.Object
- org.orekit.estimation.measurements.GroundStation

```
public class GroundStation
extends Object
```
Class modeling a ground station that can perform some measurements.
This class adds a position offset parameter to a base topocentric frame.

Since 9.0, this class also adds parameters for an additional polar motion and an additional prime meridian orientation. Since these parameters will have the same name for all ground stations, they will be managed consistently and allow to estimate Earth orientation precisely (this is needed for precise orbit determination). The polar motion and prime meridian orientation will be applied after regular Earth orientation parameters, so the value of the estimated parameters will be correction to EOP, they will not be the complete EOP values by themselves. Basically, this means that for Earth, the following transforms are applied in order, between inertial frame and ground station frame (for non-Earth based ground stations, different precession nutation models and associated planet oritentation parameters would be applied, if available):

Since 9.3, this class also adds a station clock offset parameter, which manages the value that must be subtracted from the observed measurement date to get the real physical date at which the measurement was performed (i.e. the offset is negative if the ground station clock is slow and positive if it is fast).
1. precession/nutation, as theoretical model plus celestial pole EOP parameters
2. body rotation, as theoretical model plus prime meridian EOP parameters
3. polar motion, which is only from EOP parameters (no theoretical models)
4. additional body rotation, controlled by getPrimeMeridianOffsetDriver() and getPrimeMeridianDriftDriver()
5. additional polar motion, controlled by getPolarOffsetXDriver(), getPolarDriftXDriver(), getPolarOffsetYDriver() and getPolarDriftYDriver()
6. station clock offset, controlled by getClockOffsetDriver()
7. station position offset, controlled by getEastOffsetDriver(), getNorthOffsetDriver() and getZenithOffsetDriver()
Since:

8.0

Author:

Luc Maisonobe

Field Summary

Fields
Modifier and Type	Field	Description
`static String`	`ACCELERATION_SUFFIX`	Suffix for ground clock drift parameters name.
`static String`	`DRIFT_SUFFIX`	Suffix for ground clock drift parameters name.
`static String`	`INTERMEDIATE_SUFFIX`	Suffix for ground station intermediate frame name.
`static String`	`OFFSET_SUFFIX`	Suffix for ground station position and clock offset parameters names.

Constructor Summary

Constructors
Constructor	Description
`GroundStation(TopocentricFrame baseFrame)`	Build a ground station ignoring `station displacements`.
`GroundStation(TopocentricFrame baseFrame, EOPHistory eopHistory, StationDisplacement... displacements)`	Deprecated. as of 12.1, replaced by `GroundStation(TopocentricFrame, PressureTemperatureHumidityProvider, EOPHistory, StationDisplacement...)`
`GroundStation(TopocentricFrame baseFrame, PressureTemperatureHumidityProvider pthProvider)`	Build a ground station ignoring `station displacements`.
`GroundStation(TopocentricFrame baseFrame, PressureTemperatureHumidityProvider pthProvider, EOPHistory eopHistory, StationDisplacement... displacements)`	Simple constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`TopocentricFrame`	`getBaseFrame()`	Get the base frame associated with the station.
`ParameterDriver`	`getClockAccelerationDriver()`	Get a driver allowing to change station clock acceleration (which is related to measurement date).
`ParameterDriver`	`getClockDriftDriver()`	Get a driver allowing to change station clock drift (which is related to measurement date).
`ParameterDriver`	`getClockOffsetDriver()`	Get a driver allowing to change station clock (which is related to measurement date).
`StationDisplacement[]`	`getDisplacements()`	Get the displacement models.
`ParameterDriver`	`getEastOffsetDriver()`	Get a driver allowing to change station position along East axis.
`Frame`	`getEstimatedEarthFrame()`	Get the estimated Earth frame, including the estimated linear models for pole and prime meridian.
`UT1Scale`	`getEstimatedUT1()`	Get the estimated UT1 scale, including the estimated linear models for prime meridian.
`ParameterDriver`	`getNorthOffsetDriver()`	Get a driver allowing to change station position along North axis.
`GeodeticPoint`	`getOffsetGeodeticPoint(AbsoluteDate date)`	Get the geodetic point at the center of the offset frame.
`<T extends CalculusFieldElement<T>> FieldGeodeticPoint<T>`	`getOffsetGeodeticPoint(FieldAbsoluteDate<T> date)`	Get the geodetic point at the center of the offset frame.
`Transform`	`getOffsetToInertial(Frame inertial, AbsoluteDate date, boolean clockOffsetAlreadyApplied)`	Get the transform between offset frame and inertial frame.
`FieldTransform<Gradient>`	`getOffsetToInertial(Frame inertial, AbsoluteDate clockDate, int freeParameters, Map<String,Integer> indices)`	Get the transform between offset frame and inertial frame with derivatives.
`FieldTransform<Gradient>`	`getOffsetToInertial(Frame inertial, FieldAbsoluteDate<Gradient> offsetCompensatedDate, int freeParameters, Map<String,Integer> indices)`	Get the transform between offset frame and inertial frame with derivatives.
`ParameterDriver`	`getPolarDriftXDriver()`	Get a driver allowing to add a polar drift along X.
`ParameterDriver`	`getPolarDriftYDriver()`	Get a driver allowing to add a polar drift along Y.
`ParameterDriver`	`getPolarOffsetXDriver()`	Get a driver allowing to add a polar offset along X.
`ParameterDriver`	`getPolarOffsetYDriver()`	Get a driver allowing to add a polar offset along Y.
`PressureTemperatureHumidity`	`getPressureTemperatureHumidity(AbsoluteDate date)`	Get the weather parameters.
`<T extends CalculusFieldElement<T>> FieldPressureTemperatureHumidity<T>`	`getPressureTemperatureHumidity(FieldAbsoluteDate<T> date)`	Get the weather parameters.
`ParameterDriver`	`getPrimeMeridianDriftDriver()`	Get a driver allowing to add a prime meridian rotation rate.
`ParameterDriver`	`getPrimeMeridianOffsetDriver()`	Get a driver allowing to add a prime meridian rotation.
`ParameterDriver`	`getZenithOffsetDriver()`	Get a driver allowing to change station position along Zenith axis.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - OFFSET_SUFFIX
```
public static final String OFFSET_SUFFIX
```
    Suffix for ground station position and clock offset parameters names.
    
    See Also:
    
    Constant Field Values
  - DRIFT_SUFFIX
```
public static final String DRIFT_SUFFIX
```
    Suffix for ground clock drift parameters name.
    
    See Also:
    
    Constant Field Values
  - ACCELERATION_SUFFIX
```
public static final String ACCELERATION_SUFFIX
```
    Suffix for ground clock drift parameters name.
    
    Since:
    
    12.1
    
    See Also:
    
    Constant Field Values
  - INTERMEDIATE_SUFFIX
```
public static final String INTERMEDIATE_SUFFIX
```
    Suffix for ground station intermediate frame name.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - GroundStation
```
public GroundStation(TopocentricFrame baseFrame)
```
    Build a ground station ignoring station displacements.
    Calls GroundStation(TopocentricFrame, PressureTemperatureHumidityProvider) with TroposphericModelUtils.STANDARD_ATMOSPHERE_PROVIDER as the provider.
    
    The initial values for the pole and prime meridian parametric linear models (getPrimeMeridianOffsetDriver(), getPrimeMeridianDriftDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver()) are set to 0. The initial values for the station offset model (getClockOffsetDriver(), getEastOffsetDriver(), getNorthOffsetDriver(), getZenithOffsetDriver()) are set to 0. This implies that as long as these values are not changed, the offset frame is the same as the base frame. As soon as some of these models are changed, the offset frame moves away from the base frame.
    
    Parameters:
    
    baseFrame - base frame associated with the station, without *any* parametric model (no station offset, no polar motion, no meridian shift)
    
    See Also:
    
    GroundStation(TopocentricFrame, EOPHistory, StationDisplacement...)
  - GroundStation
```
public GroundStation(TopocentricFrame baseFrame,
                     PressureTemperatureHumidityProvider pthProvider)
```
    Build a ground station ignoring station displacements.
    The initial values for the pole and prime meridian parametric linear models (getPrimeMeridianOffsetDriver(), getPrimeMeridianDriftDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver()) are set to 0. The initial values for the station offset model (getClockOffsetDriver(), getEastOffsetDriver(), getNorthOffsetDriver(), getZenithOffsetDriver()) are set to 0. This implies that as long as these values are not changed, the offset frame is the same as the base frame. As soon as some of these models are changed, the offset frame moves away from the base frame.
    
    Parameters:
    
    baseFrame - base frame associated with the station, without *any* parametric model (no station offset, no polar motion, no meridian shift)
    
    pthProvider - provider for weather parameters
    
    Since:
    
    12.1
    
    See Also:
    
    GroundStation(TopocentricFrame, EOPHistory, StationDisplacement...)
  - GroundStation
```
@Deprecated
public GroundStation(TopocentricFrame baseFrame,
                     EOPHistory eopHistory,
                     StationDisplacement... displacements)
```
    Deprecated.
    as of 12.1, replaced by GroundStation(TopocentricFrame, PressureTemperatureHumidityProvider, EOPHistory, StationDisplacement...)
    
    Simple constructor.
    The initial values for the pole and prime meridian parametric linear models (getPrimeMeridianOffsetDriver(), getPrimeMeridianDriftDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver()) are set to 0. The initial values for the station offset model (getClockOffsetDriver(), getEastOffsetDriver(), getNorthOffsetDriver(), getZenithOffsetDriver(), getClockOffsetDriver()) are set to 0. This implies that as long as these values are not changed, the offset frame is the same as the base frame. As soon as some of these models are changed, the offset frame moves away from the base frame.
    
    Parameters:
    
    baseFrame - base frame associated with the station, without *any* parametric model (no station offset, no polar motion, no meridian shift)
    
    eopHistory - EOP history associated with Earth frames
    
    displacements - ground station displacement model (tides, ocean loading, atmospheric loading, thermal effects...)
    
    Since:
    
    9.1
  - GroundStation
```
public GroundStation(TopocentricFrame baseFrame,
                     PressureTemperatureHumidityProvider pthProvider,
                     EOPHistory eopHistory,
                     StationDisplacement... displacements)
```
    Simple constructor.
    The initial values for the pole and prime meridian parametric linear models (getPrimeMeridianOffsetDriver(), getPrimeMeridianDriftDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver()) are set to 0. The initial values for the station offset model (getClockOffsetDriver(), getEastOffsetDriver(), getNorthOffsetDriver(), getZenithOffsetDriver(), getClockOffsetDriver()) are set to 0. This implies that as long as these values are not changed, the offset frame is the same as the base frame. As soon as some of these models are changed, the offset frame moves away from the base frame.
    
    Parameters:
    
    baseFrame - base frame associated with the station, without *any* parametric model (no station offset, no polar motion, no meridian shift)
    
    pthProvider - provider for weather parameters
    
    eopHistory - EOP history associated with Earth frames
    
    displacements - ground station displacement model (tides, ocean loading, atmospheric loading, thermal effects...)
    
    Since:
    
    12.1
- Method Detail
  - getPressureTemperatureHumidity
```
public PressureTemperatureHumidity getPressureTemperatureHumidity(AbsoluteDate date)
```
    Get the weather parameters.
    
    Parameters:
    
    date - date at which weather parameters are requested
    
    Returns:
    
    weather parameters
    
    Since:
    
    12.1
  - getPressureTemperatureHumidity
```
public <T extends CalculusFieldElement<T>> FieldPressureTemperatureHumidity<T> getPressureTemperatureHumidity(FieldAbsoluteDate<T> date)
```
    Get the weather parameters.
    
    Type Parameters:
    
    T - type of the field elements
    
    Parameters:
    
    date - date at which weather parameters are requested
    
    Returns:
    
    weather parameters
    
    Since:
    
    12.1
  - getDisplacements
```
public StationDisplacement[] getDisplacements()
```
    Get the displacement models.
    
    Returns:
    
    displacement models (empty if no model has been set up)
    
    Since:
    
    9.1
  - getClockOffsetDriver
```
public ParameterDriver getClockOffsetDriver()
```
    Get a driver allowing to change station clock (which is related to measurement date).
    
    Returns:
    
    driver for station clock offset
    
    Since:
    
    9.3
  - getClockDriftDriver
```
public ParameterDriver getClockDriftDriver()
```
    Get a driver allowing to change station clock drift (which is related to measurement date).
    
    Returns:
    
    driver for station clock drift
    
    Since:
    
    10.3
  - getClockAccelerationDriver
```
public ParameterDriver getClockAccelerationDriver()
```
    Get a driver allowing to change station clock acceleration (which is related to measurement date).
    
    Returns:
    
    driver for station clock acceleration
    
    Since:
    
    12.1
  - getEastOffsetDriver
```
public ParameterDriver getEastOffsetDriver()
```
    Get a driver allowing to change station position along East axis.
    
    Returns:
    
    driver for station position offset along East axis
  - getNorthOffsetDriver
```
public ParameterDriver getNorthOffsetDriver()
```
    Get a driver allowing to change station position along North axis.
    
    Returns:
    
    driver for station position offset along North axis
  - getZenithOffsetDriver
```
public ParameterDriver getZenithOffsetDriver()
```
    Get a driver allowing to change station position along Zenith axis.
    
    Returns:
    
    driver for station position offset along Zenith axis
  - getPrimeMeridianOffsetDriver
```
public ParameterDriver getPrimeMeridianOffsetDriver()
```
    Get a driver allowing to add a prime meridian rotation.
    The parameter is an angle in radians. In order to convert this value to a DUT1 in seconds, the value must be divided by ave = 7.292115146706979e-5 (which is the nominal Angular Velocity of Earth from the TIRF model).
    
    Returns:
    
    driver for prime meridian rotation
  - getPrimeMeridianDriftDriver
```
public ParameterDriver getPrimeMeridianDriftDriver()
```
    Get a driver allowing to add a prime meridian rotation rate.
    The parameter is an angle rate in radians per second. In order to convert this value to a LOD in seconds, the value must be multiplied by -86400 and divided by ave = 7.292115146706979e-5 (which is the nominal Angular Velocity of Earth from the TIRF model).
    
    Returns:
    
    driver for prime meridian rotation rate
  - getPolarOffsetXDriver
```
public ParameterDriver getPolarOffsetXDriver()
```
    Get a driver allowing to add a polar offset along X.
    The parameter is an angle in radians
    
    Returns:
    
    driver for polar offset along X
  - getPolarDriftXDriver
```
public ParameterDriver getPolarDriftXDriver()
```
    Get a driver allowing to add a polar drift along X.
    The parameter is an angle rate in radians per second
    
    Returns:
    
    driver for polar drift along X
  - getPolarOffsetYDriver
```
public ParameterDriver getPolarOffsetYDriver()
```
    Get a driver allowing to add a polar offset along Y.
    The parameter is an angle in radians
    
    Returns:
    
    driver for polar offset along Y
  - getPolarDriftYDriver
```
public ParameterDriver getPolarDriftYDriver()
```
    Get a driver allowing to add a polar drift along Y.
    The parameter is an angle rate in radians per second
    
    Returns:
    
    driver for polar drift along Y
  - getBaseFrame
```
public TopocentricFrame getBaseFrame()
```
    Get the base frame associated with the station.
    The base frame corresponds to a null position offset, null polar motion, null meridian shift
    
    Returns:
    
    base frame associated with the station
  - getEstimatedEarthFrame
```
public Frame getEstimatedEarthFrame()
```
    Get the estimated Earth frame, including the estimated linear models for pole and prime meridian.
    This frame is bound to the driver for prime meridian offset, driver prime meridian drift, driver for polar offset along X, driver for polar drift along X, driver for polar offset along Y, driver for polar drift along Y, so its orientation changes when the setValue methods of the drivers are called.
    
    Returns:
    
    estimated Earth frame
    
    Since:
    
    9.1
  - getEstimatedUT1
```
public UT1Scale getEstimatedUT1()
```
    Get the estimated UT1 scale, including the estimated linear models for prime meridian.
    This time scale is bound to the driver for prime meridian offset, and driver prime meridian drift, so its offset from UTC changes when the setValue methods of the drivers are called.
    
    Returns:
    
    estimated Earth frame
    
    Since:
    
    9.1
  - getOffsetGeodeticPoint
```
public GeodeticPoint getOffsetGeodeticPoint(AbsoluteDate date)
```
    Get the geodetic point at the center of the offset frame.
    
    Parameters:
    
    date - current date (may be null if displacements are ignored)
    
    Returns:
    
    geodetic point at the center of the offset frame
    
    Since:
    
    9.1
  - getOffsetGeodeticPoint
```
public <T extends CalculusFieldElement<T>> FieldGeodeticPoint<T> getOffsetGeodeticPoint(FieldAbsoluteDate<T> date)
```
    Get the geodetic point at the center of the offset frame.
    
    Type Parameters:
    
    T - type of the field elements
    
    Parameters:
    
    date - current date(must be non-null, which is a more stringent condition * than in getOffsetGeodeticPoint(AbsoluteDate)
    
    Returns:
    
    geodetic point at the center of the offset frame
    
    Since:
    
    12.1
  - getOffsetToInertial
```
public Transform getOffsetToInertial(Frame inertial,
                                     AbsoluteDate date,
                                     boolean clockOffsetAlreadyApplied)
```
    Get the transform between offset frame and inertial frame.
    The offset frame takes the current position offset, polar motion and the meridian shift into account. The frame returned is disconnected from later changes in the parameters. When the parameters managing these offsets are changed, the method must be called again to retrieve a new offset frame.
    
    Parameters:
    
    inertial - inertial frame to transform to
    
    date - date of the transform
    
    clockOffsetAlreadyApplied - if true, the specified date is as read by the ground station clock (i.e. clock offset not compensated), if false, the specified date was already compensated and is a physical absolute date
    
    Returns:
    
    transform between offset frame and inertial frame, at real measurement date (i.e. with clock, Earth and station offsets applied)
  - getOffsetToInertial
```
public FieldTransform<Gradient> getOffsetToInertial(Frame inertial,
                                                    AbsoluteDate clockDate,
                                                    int freeParameters,
                                                    Map<String,Integer> indices)
```
    Get the transform between offset frame and inertial frame with derivatives.
    As the East and North vectors are not well defined at pole, the derivatives of these two vectors diverge to infinity as we get closer to the pole. So this method should not be used for stations less than 0.0001 degree from either poles.
    
    Parameters:
    
    inertial - inertial frame to transform to
    
    clockDate - date of the transform as read by the ground station clock (i.e. clock offset not compensated)
    
    freeParameters - total number of free parameters in the gradient
    
    indices - indices of the estimated parameters in derivatives computations, must be driver span name in map, not driver name or will not give right results (see ParameterDriver.getValue(int, Map))
    
    Returns:
    
    transform between offset frame and inertial frame, at real measurement date (i.e. with clock, Earth and station offsets applied)
    
    Since:
    
    10.2
    
    See Also:
    
    getOffsetToInertial(Frame, FieldAbsoluteDate, int, Map)
  - getOffsetToInertial
```
public FieldTransform<Gradient> getOffsetToInertial(Frame inertial,
                                                    FieldAbsoluteDate<Gradient> offsetCompensatedDate,
                                                    int freeParameters,
                                                    Map<String,Integer> indices)
```
    Get the transform between offset frame and inertial frame with derivatives.
    As the East and North vectors are not well defined at pole, the derivatives of these two vectors diverge to infinity as we get closer to the pole. So this method should not be used for stations less than 0.0001 degree from either poles.
    
    Parameters:
    
    inertial - inertial frame to transform to
    
    offsetCompensatedDate - date of the transform, clock offset and its derivatives already compensated
    
    freeParameters - total number of free parameters in the gradient
    
    indices - indices of the estimated parameters in derivatives computations, must be driver span name in map, not driver name or will not give right results (see ParameterDriver.getValue(int, Map))
    
    Returns:
    
    transform between offset frame and inertial frame, at specified date
    
    Since:
    
    10.2

Class GroundStation

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

OFFSET_SUFFIX

DRIFT_SUFFIX

ACCELERATION_SUFFIX

INTERMEDIATE_SUFFIX

Constructor Detail

GroundStation

GroundStation

GroundStation

GroundStation

Method Detail

getPressureTemperatureHumidity

getPressureTemperatureHumidity

getDisplacements

getClockOffsetDriver

getClockDriftDriver

getClockAccelerationDriver

getEastOffsetDriver

getNorthOffsetDriver

getZenithOffsetDriver

getPrimeMeridianOffsetDriver

getPrimeMeridianDriftDriver

getPolarOffsetXDriver

getPolarDriftXDriver

getPolarOffsetYDriver

getPolarDriftYDriver

getBaseFrame

getEstimatedEarthFrame

getEstimatedUT1

getOffsetGeodeticPoint

getOffsetGeodeticPoint

getOffsetToInertial

getOffsetToInertial

getOffsetToInertial