net.sf.marineapi.nmea.sentence

Interface AISSentence

All Superinterfaces:

Sentence

public interface AISSentence
extends Sentence

Base interface for all AIS sentences (Automatic Identification System). Notice that "AIS" does not refer to NMEA sentence type, but another system/standard that transmits it's messages using NMEA 0183.

AIS sentences are parsed in two phases and they all share the same NMEA sentence layout, so there is no dedicated interfaces for each AIS sentence type (VDM, VDO etc).

Example:
!AIVDM,1,1,,B,177KQJ5000G?tO`K>RA1wUbN0TKH,0*5C

Author:

Lázár József, Kimmo Tuukkanen

Field Summary

Fields inherited from interface net.sf.marineapi.nmea.sentence.Sentence

ALTERNATIVE_BEGIN_CHAR, BEGIN_CHAR, CHECKSUM_DELIMITER, FIELD_DELIMITER, MAX_LENGTH, TERMINATOR

Method Summary

Modifier and Type	Method and Description
int	getFillBits() Returns the number of fill bits required to pad the data payload to a 6 bit boundary, ranging from 0 to 5.
int	getFragmentNumber() Returns the fragment number of this sentence (1-based).
String	getMessageId() Returns the sequential message ID for multi-sentence messages.
int	getNumberOfFragments() Number of fragments in the currently accumulating message.
String	getPayload() Returns the raw 6-bit decoded message.
String	getRadioChannel() Returns the radio channel information of the messsage.
boolean	isFirstFragment() Tells if this is the first fragment in message sequence.
boolean	isFragmented() Tells if the AIS message is being delivered over multiple sentences.
boolean	isLastFragment() Tells if this is the last fragment in message sequence.
boolean	isPartOfMessage(AISSentence sentence) Tells if given sentence is part of message sequence.

Methods inherited from interface net.sf.marineapi.nmea.sentence.Sentence

getBeginChar, getFieldCount, getSentenceId, getTalkerId, isAISSentence, isProprietary, isValid, reset, setBeginChar, setTalkerId, toSentence, toSentence, toString

Method Detail

getNumberOfFragments

int getNumberOfFragments()

Number of fragments in the currently accumulating message.

Returns:

number of fragments.

getFragmentNumber

int getFragmentNumber()

Returns the fragment number of this sentence (1-based).

Returns:

fragment index

getMessageId

String getMessageId()

Returns the sequential message ID for multi-sentence messages.

Returns:

sequential message ID

getRadioChannel

String getRadioChannel()

Returns the radio channel information of the messsage.

Returns:

radio channel id

getPayload

String getPayload()

Returns the raw 6-bit decoded message.

Returns:

message body

getFillBits

int getFillBits()

Returns the number of fill bits required to pad the data payload to a 6 bit boundary, ranging from 0 to 5. Equivalently, subtracting 5 from this tells how many least significant bits of the last 6-bit nibble in the data payload should be ignored.

Returns:

number of fill bits

isFragmented

boolean isFragmented()

Tells if the AIS message is being delivered over multiple sentences.

Returns:

true if this sentence is part of a sequence

isFirstFragment

boolean isFirstFragment()

Tells if this is the first fragment in message sequence.

Returns:

true if first fragment in sequence

isLastFragment

boolean isLastFragment()

Tells if this is the last fragment in message sequence.

Returns:

true if last part of a sequence

isPartOfMessage

boolean isPartOfMessage(AISSentence sentence)

Tells if given sentence is part of message sequence.

Sentences are considered to belong in same sequence when the given sentence meets the following conditions:

• Same number of fragments, higher fragment #, same channel and same message id
• Same number of fragments, next fragment #, and either same channel or same message id

Parameters:

sentence - AISSentence to compare with.

Returns:

true if this and given sentence belong in same sequence