Package org.orekit.gnss.rflink.gps

Class SubFrame

java.lang.Object
org.orekit.gnss.rflink.gps.SubFrame
Direct Known Subclasses:
SubFrame1, SubFrame2, SubFrame3, SubFrame45
public abstract class SubFrame extends Object
Container for sub-frames in a GPS navigation message.
Since:
12.0
Author:
Luc Maisonobe

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected static final int
    PARITY_SIZE
    Size of parity field.
    static final int
    PREAMBLE_VALUE
    TLM preamble.
    protected static final int
    WORD_SIZE
    Words size.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    SubFrame(int[] words, int nbFields)
    Simple constructor.

  • Method Summary

    Modifier and Type
    Method
    Description
    static boolean
    checkParity(int previous, int current)
    Check parity.
    int
    getAlert()
    Get alert flag.
    int
    getAntiSpoofing()
    Get anti-spoofing flag.
    protected int
    getField(int fieldIndex)
    Get a field.
    int
    getId()
    Get sub-frame id.
    int
    getIntegrityStatus()
    Get integrity status flag.
    int
    getMessage()
    Get telemetry message.
    int
    getPreamble()
    Get telemetry preamble.
    int
    getTow()
    Get Time Of Week of next 12 second message.
    boolean
    hasParityErrors()
    Check if the sub-frame has parity errors.
    static SubFrame
    parse(EncodedMessage encodedMessage)
    Builder for sub-frames.
    protected void
    setField(int fieldIndex, int wordIndex, int shift, int nbBits, int[] words)
    Set a field.
    protected void
    setField(int fieldIndex, int wordIndexMSB, int shiftMSB, int nbBitsMSB, int wordIndexLSB, int shiftLSB, int nbBitsLSB, int[] words)
    Set a field.

    Methods inherited from class java.lang.Object

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

  • Field Details

  • Constructor Details

    • SubFrame

      protected SubFrame(int[] words, int nbFields)
      Simple constructor.
      Parameters:
      words - raw words
      nbFields - number of fields in the sub-frame (including TLM and HOW data fields, excluding non-information and parity)

  • Method Details

    • parse

      public static SubFrame parse(EncodedMessage encodedMessage)
      Builder for sub-frames.

      This builder creates the proper sub-frame type corresponding to the ID in handover word and the SV Id for sub-frames 4 and 5.

      Parameters:
      encodedMessage - encoded message containing exactly one sub-frame
      Returns:
      sub-frame with TLM and HOW fields already set up
      See Also:

    • checkParity

      public static boolean checkParity(int previous, int current)
      Check parity.

      This implements algorithm in table 20-XIV from IS-GPS-200N

      Parameters:
      previous - previous 30 bits word (only two least significant bits are used)
      current - current 30 bits word
      Returns:
      true if parity check succeeded

    • hasParityErrors

      public boolean hasParityErrors()
      Check if the sub-frame has parity errors.
      Returns:
      true if frame has parity errors

    • getField

      protected int getField(int fieldIndex)
      Get a field.

      The field indices are defined as constants in the various sub-frames classes.

      Parameters:
      fieldIndex - field index (counting from 0)
      Returns:
      field value

    • setField

      protected void setField(int fieldIndex, int wordIndex, int shift, int nbBits, int[] words)
      Set a field.
      Parameters:
      fieldIndex - field index (counting from 0)
      wordIndex - word index (counting from 1, to match IS-GPS-200 tables)
      shift - right shift to apply (i.e. number of LSB bits for next fields that should be removed)
      nbBits - number of bits in the field
      words - raw 30 bits words

    • setField

      protected void setField(int fieldIndex, int wordIndexMSB, int shiftMSB, int nbBitsMSB, int wordIndexLSB, int shiftLSB, int nbBitsLSB, int[] words)
      Set a field.
      Parameters:
      fieldIndex - field index (counting from 0)
      wordIndexMSB - word index containing MSB (counting from 1, to match IS-GPS-200 tables)
      shiftMSB - right shift to apply to MSB (i.e. number of LSB bits for next fields that should be removed)
      nbBitsMSB - number of bits in the MSB
      wordIndexLSB - word index containing LSB (counting from 1, to match IS-GPS-200 tables)
      shiftLSB - right shift to apply to LSB (i.e. number of LSB bits for next fields that should be removed)
      nbBitsLSB - number of bits in the LSB
      words - raw 30 bits words

    • getPreamble

      public int getPreamble()
      Get telemetry preamble.
      Returns:
      telemetry preamble

    • getMessage

      public int getMessage()
      Get telemetry message.
      Returns:
      telemetry message

    • getIntegrityStatus

      public int getIntegrityStatus()
      Get integrity status flag.
      Returns:
      integrity status flag

    • getTow

      public int getTow()
      Get Time Of Week of next 12 second message.
      Returns:
      Time Of Week of next 12 second message (s)

    • getAlert

      public int getAlert()
      Get alert flag.
      Returns:
      alert flag

    • getAntiSpoofing

      public int getAntiSpoofing()
      Get anti-spoofing flag.
      Returns:
      anti-spoofing flag

    • getId

      public int getId()
      Get sub-frame id.
      Returns:
      sub-frame id