Geoid Height

Calculate undulations/height

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  • Library:

  • Aerospace Blockset / Environment / Gravity

  • Geoid Height block

Description

The Geoid Height block calculates the geoid height using the Geopotential model parameter. The block interpolates the geoid heights from a grid of point values in the tide-free system. It uses the specified geopotential model to degree and order of the model. The geoid undulations are relative to the WGS84 ellipsoid.

The interpolation scheme wraps over the poles to allow for geoid height calculations at and near these locations.

Limitations

This block has the limitations of the selected geopotential model.

Ports

Input

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Geodetic latitude, specified as a scalar, in degrees, where north latitude is positive and south latitude is negative. Input latitude must be of type single or double. If latitude is not in the range from –90 to 90, the block wraps it to be within the range.

Data Types: double | single

Longitude, specified as a scalar, in degrees, where east longitude is positive in the range from 0 to 360. Input longitude must be of type single or double. If longitude is not in the range from 0 to 360, the block wraps it to be within the range when Action for out-of-range input is set to None or Warning. It does not wrap when Action for out-of-range input is set to Error.

Data Types: double | single

Output

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Geoid height, returned as a scalar, in selected length units. The data type is the same as the latitude in the first input.

Data Types: double | single

Parameters

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Parameter and output units, specified as:

Units

Height

Metric (MKS)

Meters

English

Feet

Programmatic Use

Block Parameter: units
Type: character vector
Values: 'Metric (MKS)' | 'English'
Default: 'Metric (MKS)'

Geopotential model, specified as:

Geopotential ModelDescription
EGM96 (Earth)

Default. EGM96 Geopotential Model to degree and order 360. This model uses a 15-minute grid of point values in the tide-free system. This block calculates geoid heights to an accuracy of 0.01 m for this model.

EGM2008 (Earth)

EGM2008 Geopotential Model to degree and order 2159. This model uses a 2.5-minute grid of point values in the tide-free system. This block calculates geoid heights to an accuracy of 0.001 m for this model.

Note

This block requires that you download geoid data for the EGM2008 Geopotential Model with the Add-On Explorer. Click the Get data button to start the Add-On Explorer. For more information, see aeroDataPackage. If the data is installed, the Get data button does not appear.

Custom

Custom geopotential model that you define in Geopotential mat-file. This block calculates geoid heights to an accuracy of 0.01 m for custom models. Selecting Custom enables the Geopotential mat-file parameter.

Programmatic Use

Block Parameter: gtype
Type: character vector
Values: 'EGM96' | 'EGM2008' | 'Custom'
Default: 'Earth'

Geopotential MAT-file that defines your custom geopotential model.

Dependencies

To enable this, set Geopotential model to Custom.

Programmatic Use

Block Parameter: datafile
Type: character vector
Values: 'geoidegm96grid' | MAT-file
Default: 'geoidegm96grid'

Data type of the input and output signals, specified as double or single.

Programmatic Use

Block Parameter: dtype
Type: character vector
Values: 'double' | 'single'
Default: 'double'

Out-of-range input behavior (latitude outside –90 to 90 degrees, longitude outside 0 to 360 degrees), specified as follows.

ActionDescription

None

No action.

Warning

Warning in the Diagnostic Viewer.

Error (default)

MATLAB® returns an exception, model simulation stops.

Programmatic Use

Block Parameter: action
Type: character vector
Values: 'None' | 'Warning' | 'Error'
Default: 'Warning'

References

[1] Vallado, David. Fundamentals of Astrodynamics and Applications. New York: McGraw-Hill, 1997.

[2] "Department of Defense World Geodetic System 1984, Its Definition, and Relationship with Local Geodetic Systems." NIMA TR8350.2.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

See Also

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External Websites

Introduced in R2010b

Aerospace Blockset Documentation

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