org.orekit.files.ccsds

Class StreamingAemWriter

java.lang.Object

org.orekit.files.ccsds.StreamingAemWriter

public class StreamingAemWriter
extends Object

A writer for AEM files.

Each instance corresponds to a single AEM file.

Metadata

The AEM metadata used by this writer is described in the following table. Many metadata items are optional or have default values so they do not need to be specified. At a minimum the user must supply those values that are required and for which no default exits: Keyword.OBJECT_NAME, and Keyword.OBJECT_ID. The usage column in the table indicates where the metadata item is used, either in the AEM header or in the metadata section at the start of an AEM attitude segment.

The AEM metadata for the whole AEM file is set in the constructor.

Keyword	Usage	Obligatory	Default	Reference
Keyword.CCSDS_AEM_VERS	Header	Yes	CCSDS_AEM_VERS	Table 4-2
Keyword.COMMENT	Header	No		Table 4-2
Keyword.CREATION_DATE	Header	Yes	Now	Table 4-2
Keyword.ORIGINATOR	Header	Yes	DEFAULT_ORIGINATOR	Table 4-2
Keyword.OBJECT_NAME	Segment	Yes		Table 4-3
Keyword.OBJECT_ID	Segment	Yes		Table 4-3
Keyword.CENTER_NAME	Segment	No		Table 4-3
Keyword.REF_FRAME_A	Segment	Yes		Table 4-3
Keyword.REF_FRAME_B	Segment	Yes		Table 4-3
Keyword.ATTITUDE_DIR	Segment	Yes		Table 4-3
Keyword.TIME_SYSTEM	Segment	Yes		Table 4-3, Annex A
Keyword.START_TIME	Segment	Yes		Table 4-3
Keyword.USEABLE_START_TIME	Segment	No		Table 4-3
Keyword.STOP_TIME	Segment	Yes		Table 4-3
Keyword.USEABLE_STOP_TIME	Segment	No		Table 4-3
Keyword.ATTITUDE_TYPE	Segment	Yes		Table 4-3, 4-4
Keyword.QUATERNION_TYPE	Segment	No		Table 4-3, 4-4
Keyword.EULER_ROT_SEQ	Segment	No		Table 4-3
Keyword.RATE_FRAME	Segment	No		Table 4-3
Keyword.INTERPOLATION_METHOD	Segment	No		Table 4-3
Keyword.INTERPOLATION_DEGREE	Segment	No		Table 4-3

The Keyword.TIME_SYSTEM must be constant for the whole file and is used to interpret all dates except Keyword.CREATION_DATE. The guessing algorithm is not guaranteed to work so it is recommended to provide values for Keyword.CENTER_NAME and Keyword.TIME_SYSTEM to avoid any bugs associated with incorrect guesses.

Standardized values for Keyword.TIME_SYSTEM are GMST, GPS, MET, MRT, SCLK, TAI, TCB, TDB, TT, UT1, and UTC. Standardized values for reference frames are EME2000, GTOD, ICRF, ITRF2000, ITRF-93, ITRF-97, LVLH, RTN, QSW, TOD, TNW, NTW and RSW. Additionally ITRF followed by a four digit year may be used.

Since:

10.2

Author:

Bryan Cazabonne

See Also:

CCSDS 504.0-B-1 Attitude Data Messages, AEMWriter

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	StreamingAemWriter.AEMSegment A writer for a segment of an AEM.

Field Summary

Fields

Modifier and Type	Field and Description
static String	CCSDS_AEM_VERS Version number implemented.
static String	DEFAULT_ORIGINATOR Default value for Keyword.ORIGINATOR.

Constructor Summary

Constructors

Constructor and Description
StreamingAemWriter(Appendable writer, TimeScale timeScale, Map<Keyword,String> metadata) Create an AEM writer that streams data to the given output stream.

Method Summary

Modifier and Type	Method and Description
StreamingAemWriter.AEMSegment	newSegment(Map<Keyword,String> segmentMetadata) Create a writer for a new AEM attitude ephemeris segment.
void	writeHeader() Writes the standard AEM header for the file.

Methods inherited from class java.lang.Object

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

Field Detail

CCSDS_AEM_VERS

public static final String CCSDS_AEM_VERS

Version number implemented.

See Also:

Constant Field Values

DEFAULT_ORIGINATOR

public static final String DEFAULT_ORIGINATOR

Default value for Keyword.ORIGINATOR.

See Also:

Constant Field Values

Constructor Detail

StreamingAemWriter

public StreamingAemWriter(Appendable writer,
                          TimeScale timeScale,
                          Map<Keyword,String> metadata)

Create an AEM writer that streams data to the given output stream.

Parameters:

writer - The output stream for the AEM file. Most methods will append data to this writer.

timeScale - for all times in the AEM except Keyword.CREATION_DATE. See Section 4.2.5.4.2 and Annex A.

metadata - for the satellite.

Method Detail

writeHeader

public void writeHeader()
                 throws IOException

Writes the standard AEM header for the file.

Throws:

IOException - if the stream cannot write to stream

newSegment

public StreamingAemWriter.AEMSegment newSegment(Map<Keyword,String> segmentMetadata)

Create a writer for a new AEM attitude ephemeris segment.

The returned writer can only write a single attitude ephemeris segment in an AEM. This method must be called to create a writer for each attitude ephemeris segment.

Parameters:

segmentMetadata - the metadata to use for the segment. Overrides for this segment any other source of meta data values. See StreamingAemWriter(java.lang.Appendable, org.orekit.time.TimeScale, java.util.Map<org.orekit.files.ccsds.Keyword, java.lang.String>) for a description of which metadata are required and how they are determined.

Returns:

a new AEM segment, ready for writing.