Earth Orientation Parameters
Calculate Earth orientation parameters (EOP)
Libraries:
Aerospace Blockset /
Environment /
Celestial Phenomena
Description
The Earth Orientation Parameters block calculates these parameters:
Difference between the UTC and Universal Time (UT1)
Movement of the rotation axis with respect to the crust of the Earth
Adjustment to the location of the Celestial Intermediate Pole (CIP)
By default, this block uses a prepopulated list of International Earth Rotation and Reference Systems Service (IERS) data. This list contains measured and calculated (predicted) data supplied by the IERS. The IERS measures and calculates this data for a set of predetermined dates. For dates after those listed in the prepopulated list, Earth Orientation Parameters calculates the ΔUT1 using this equation, limiting the values to +/- 0.9 s:
UT1-UTC=0.5309-0.00123(MJD-57808)-(UT2-UT1)
Use this block when your application uses Earth Centered Inertial to Earth Centered Earth Fixed transformations, such as for high altitude applications.
Ports
Input
UTCMJD — UT1 for UTC
scalar
UT1 for UTC, specified as a scalar modified Julian date. Use the Julian Date Conversion block to convert the UTC date to a modified Julian date.
Data Types: double
Output
ΔUT1 — Difference between UT1 and UTC
scalar
Difference between UT1 and UTC, specified as a scalar, in seconds.
Data Types: double
[xp,yp] — Polar displacement of Earth
vector
Polar displacement of the Earth, [xp,yp], specified as a vector, in radians, from the motion of the Earth crust, along the x- and y-axes.
Data Types: double
[dX,dY] — Adjustment to location of Celestial Intermediate Pole (CIP)
vector
Adjustment to the location of the Celestial Intermediate Pole (CIP), specified as a vector, in radians. This location ([dX,dY]) is along the x- and y-axes.
Data Types: double
ΔUT1err — Return errors for the measured and predicted values in the IERS data
vector
Return errors for the measured and predicted values in the IERS data for the difference between UT1 and UTC, specified as a vector, in seconds.
Dependencies
This port is enabled when the Output parameter error is selected.
[xp,yp]err — Return errors for the measured and predicted values in the IERS data
vector
Return errors for the measured and predicted values in the IERS data for the polar displacement of Earth, specified as a vector, in radians.
Dependencies
This port is enabled when the Output parameter error is selected.
[dX,dY]err — Return errors for the measured and predicted values in the IERS data
vector
Return errors for the measured and predicted values in the IERS data for the adjustment to location of Celestial Intermediate Pole (CIP), specified as a vector, in radians.
Dependencies
This port is enabled when the Output parameter error is selected.
Parameters
IERS data file — Earth orientation data
aeroiersdata.mat
(default) | MAT-file
Custom list of Earth orientation data, specified in a MAT-file.
Programmatic Use
Block Parameter:
FileName |
Type: character vector |
Values: scalar |
Default:
'aeroiersdata.mat' |
Output parameter error — Enable output ports to return errors
off
(default) | on
Select this parameter to enable output ports to return errors for the measured and predicted values in the IERS data file:
Difference between UT1 and UTC
Polar displacement of Earth
Adjustment to location of Celestial Intermediate Pole (CIP)
Dependencies
Selecting this check box enables these ports:
ΔUT1err
[xp,yp]err
[dX,dY]err
Programmatic Use
Block Parameter:
OutputError |
Type: character vector |
Values: scalar |
Default:
'off' |
Action for out-of-range input — Out-of-range block behavior
None
(default) | Warning
| Error
Out-of-range block behavior, specified as:
Action | Description |
---|---|
| No action. |
| Warning in the Diagnostic Viewer, model simulation continues. |
| Error in the Diagnostic Viewer, model simulation stops. |
Programmatic Use
Block Parameter: action |
Type: character vector |
Values: 'None' | 'Warning' | 'Error' |
Default: 'Warning' |
IERS data URL — Web site or Earth orientation data file
http://maia.usno.navy.mil/ser7/finals2000A.data
(default) | web site address | file name
Web site or Earth orientation data file containing the Earth orientation data according to the IAU 2000A, specified as a web site address or file name.
Note
If you receive an error message while accessing the default site, use one of these alternate sites:
https://datacenter.iers.org/data/latestVersion/10_FINALS.DATA_IAU2000_V2013_0110.txt
ftp://cddis.gsfc.nasa.gov/pub/products/iers/finals2000A.data
Programmatic Use
Block Parameter:
FileName |
Type: character vector |
Values: scalar |
Default:
'aeroiersdata.mat' |
Destination folder — Folder for IERS data file
current Folder (default)
Folder for IERS data file, specified as a character array or string. Before running this function, create foldername with write permission.
To create the IERS data file in the destination folder, click the Create button.
Programmatic Use
Block Parameter:
FileName |
Type: character vector |
Values: scalar |
Default:
'aeroiersdata.mat' |
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Version History
Introduced in R2018bR2020b: Updated aeroiersdata.mat
file
The contents of the aeroiersdata.mat
file have been updated.
Correspondingly, the output of this block will have different results when using the
default value ('aeroiersdata.mat'
) as the value of the
IERS data file parameter. The results reflect more accurate
external data from the International Earth Rotation and Reference Systems Service
(IERS).
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