Ais-decoder-ts NPM

AIS Decoder

The automatic identification system (AIS) is an automatic Tracking system used on ships and by vessel traffic services (VTS). When satellites are used to detect AIS signatures, the term Satellite-AIS (S-AIS) is used. AIS information supplements marine radar, which continues to be the primary method of collision avoidance for water transport.

Ideal Node Version : 8.16.2

Tests : run `npm test`

AIS MESSAGES

Position0 format: !AIVDM, identifies this as an AIVDM packet (AIS format).
Position1 message_count: Messages counter (number of messages), sometimes the ais messages will be split over several messages.
Position2 message_id:
Position3 sequence_id: Sequential message, the current message number
Position4 channel: vhf channel A/B
Position5 payload: the ais data itself
Position6 size: number of bits required to fill the data
<format>,<message count>,<message id>,<sequence id>,<channel A/B>,<data>,<fill bits>

Important notes:

Ais payload is represented in a 6bits encoded string

API

constructor(AIS_Messages, safeMode)
- AIS_Messages: Array of ais messages.
- safeMode: set to false by default. when true the module will never throw an error (silent mode).
getResults() - return a collection of the parse messages
private decode(input: Array<any>, session: any): void - decode the raw ais messages
private validateRawMessage(input: string): boolean - validate if the raw messages

Command Line:

node dist/bin/parse <ais message> for example: node ./dist/bin/parse "!AIVDM,1,1,,A,13u?etPv2;0n:dDPwUM1U1Cb069D,0*24"

Running example:

npm run example

Example:

// new Decoder(Array<AIS_Messages>, safeMode<Boolean>)
import { Decoder } from '../lib/index';
const aisMessages:Array<string> = [
  '!AIVDM,1,1,,A,400TcdiuiT7VDR>3nIfr6>i00000,0*78',
  '!AIVDM,2,1,0,A,58wt8Ui`g??r21`7S=:22058<v05Htp000000015>8OA;0sk,0*7B',
  '!AIVDM,2,2,0,A,eQ8823mDm3kP00000000000,2*5D',
  '!AIVDM,2,1,0,A,58wt8Ui`g??r21`7S=:22058<v05Htp000000015>8OA;0sk,0*7B ',
  '!AIVDM,2,2,0,A,eQ8823mDm3kP00000000000,2*5D',
];
const safeMode = false;
const aisDecoder_ex2 = new Decoder(aisMessages, safeMode);

// results will hold a collection of the parsed ais messages
const results = aisDecoder_ex2.getResults();