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GG-AisDecode.js
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GG-AisDecode.js
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/*
** Copyright 2014 Fulup Ar Foll.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* References:
* Gpsd : http://catb.org/gpsd/AIVDM.html [best doc]
* OpenCPN: https://github.com/OpenCPN/OpenCPN [file: AIS_Bitstring.cpp]
* http://fossies.org/linux/misc/gpsd-3.11.tar.gz/gpsd-3.11/test/sample.aivdm
* online AIS decoder http://www.maritec.co.za/tools/aisvdmvdodecoding/
*/
'use strict';
var DEBUG = false;
var MSG_TYPE = {
1: "Position Report Class A",
2: "Position Report Class A (Assigned schedule)",
3: "Position Report Class A (Response to interrogation)",
4: "Base Station Report",
5: "Static and Voyage Related Data",
6: "Binary Addressed Message",
7: "Binary Acknowledge",
8: "Binary Broadcast Message",
9: "Standard SAR Aircraft Position Report",
10: "UTC and Date Inquiry",
11: "UTC and Date Response",
12: "Addressed Safety Related Message",
13: "Safety Related Acknowledgement",
14: "Safety Related Broadcast Message",
15: "Interrogation",
16: "Assignment Mode Command",
17: "DGNSS Binary Broadcast Message",
18: "Standard Class B CS Position Report",
19: "Extended Class B Equipment Position Report",
20: "Data Link Management",
21: "Aid-to-Navigation Report",
22: "Channel Management",
23: "Group Assignment Command",
24: "Static Data Report",
25: "Single Slot Binary Message,",
26: "Multiple Slot Binary Message With Communications State",
27: "Position Report For Long-Range Applications"
};
var NAV_STATUS = {
0: "Under way using engine",
1: "At anchor",
2: "Not under command",
3: "Restricted manoeuverability",
4: "Constrained by her draught",
5: "Moored",
6: "Aground",
7: "Engaged in Fishing",
8: "Under way sailing",
9: "Reserved for future amendment of Navigational Status for HSC",
10: "Reserved for future amendment of Navigational Status for WIG",
11: "Reserved for future use",
12: "Reserved for future use",
13: "Reserved for future use",
14: "AIS-SART is active",
15: "Not defined (default)"
};
var VESSEL_TYPE= {
0: "Not available (default)",
// 1-19 Reserved for future usage
20: "Wing in ground (WIG), all ships of this type",
21: "Wing in ground (WIG), Hazardous category A",
22: "Wing in ground (WIG), Hazardous category B",
23: "Wing in ground (WIG), Hazardous category C",
24: "Wing in ground (WIG), Hazardous category D",
25: "Wing in ground (WIG), Reserved for future use",
26: "Wing in ground (WIG), Reserved for future use",
27: "Wing in ground (WIG), Reserved for future use",
28: "Wing in ground (WIG), Reserved for future use",
29: "Wing in ground (WIG), Reserved for future use",
30: "Fishing",
31: "Towing",
32: "Towing: length exceeds 200m or breadth exceeds 25m",
33: "Dredging or underwater ops",
34: "Diving ops",
35: "Military ops",
36: "Sailing",
37: "Pleasure Craft",
38: "Reserved",
39: "Reserved",
40: "High speed craft (HSC), all ships of this type",
41: "High speed craft (HSC), Hazardous category A",
42: "High speed craft (HSC), Hazardous category B",
43: "High speed craft (HSC), Hazardous category C",
44: "High speed craft (HSC), Hazardous category D",
45: "High speed craft (HSC), Reserved for future use",
46: "High speed craft (HSC), Reserved for future use",
47: "High speed craft (HSC), Reserved for future use",
48: "High speed craft (HSC), Reserved for future use",
49: "High speed craft (HSC), No additional information",
50: "Pilot Vessel",
51: "Search and Rescue vessel",
52: "Tug",
53: "Port Tender",
54: "Anti-pollution equipment",
55: "Law Enforcement",
56: "Spare - Local Vessel",
57: "Spare - Local Vessel",
58: "Medical Transport",
59: "Noncombatant ship according to RR Resolution No. 18",
60: "Passenger, all ships of this type",
61: "Passenger, Hazardous category A",
62: "Passenger, Hazardous category B",
63: "Passenger, Hazardous category C",
64: "Passenger, Hazardous category D",
65: "Passenger, Reserved for future use",
66: "Passenger, Reserved for future use",
67: "Passenger, Reserved for future use",
68: "Passenger, Reserved for future use",
69: "Passenger, No additional information",
70: "Cargo, all ships of this type",
71: "Cargo, Hazardous category A",
72: "Cargo, Hazardous category B",
73: "Cargo, Hazardous category C",
74: "Cargo, Hazardous category D",
75: "Cargo, Reserved for future use",
76: "Cargo, Reserved for future use",
77: "Cargo, Reserved for future use",
78: "Cargo, Reserved for future use",
79: "Cargo, No additional information",
80: "Tanker, all ships of this type",
81: "Tanker, Hazardous category A",
82: "Tanker, Hazardous category B",
83: "Tanker, Hazardous category C",
84: "Tanker, Hazardous category D",
85: "Tanker, Reserved for future use",
86: "Tanker, Reserved for future use",
87: "Tanker, Reserved for future use",
88: "Tanker, Reserved for future use",
89: "Tanker, No additional information",
90: "Other Type, all ships of this type",
91: "Other Type, Hazardous category A",
92: "Other Type, Hazardous category B",
93: "Other Type, Hazardous category C",
94: "Other Type, Hazardous category D",
95: "Other Type, Reserved for future use",
96: "Other Type, Reserved for future use",
97: "Other Type, Reserved for future use",
98: "Other Type, Reserved for future use",
99: "Other Type, no additional information"
};
// Ais payload is represented in a 6bits encoded string !(
// This method is a direct transcription in nodejs of C++ ais-decoder code
function AisDecode (input, session) {
this.bitarray = [];
this.valid = false; // will move to 'true' if parsing succeed
this.error = ""; // for returning error message if not valid
if (Object.prototype.toString.call(input) !== "[object String]") {
this.error = "AisDecode: Sentence is not of type string.";
return;
} else {
input = input.trim();
}
if (input.length === 0) {
this.error = "AisDecode: Sentence is empty or spaces.";
return;
} else if (!this.validateChecksum(input)) {
this.error = "AisDecode: Sentence checksum is invalid.";
return;
}
// split nmea message !AIVDM,1,1,,B,B69>7mh0?J<:>05B0`0e;wq2PHI8,0*3D'
var nmea = input.split(",");
if (nmea.length !== 7) {
this.error = "AisDecode: Sentence contains invalid number of parts.";
return;
}
var command = nmea[0].substring(3,6);
if (command !== "VDM" && // AIVDM: others
command !== "VDO" // AIVDO: own AIS
) {
this.error = "AisDecode: Invalid message prefix.";
return;
}
// the input string is part of a multipart message, make sure we were
// passed a session object.
var message_count = Number(nmea[1]);
var message_id = Number(nmea[2]);
var sequence_id = nmea[3].length > 0 ? Number(nmea[3]) : NaN;
if(message_count > 1) {
if(Object.prototype.toString.call(session) !== "[object Object]") {
throw "A session object is required to maintain state for decoding multipart AIS messages.";
}
if(message_id > 1) {
if(nmea[0] !== session.formatter) {
this.error = "AisDecode: Sentence does not match formatter of current session.";
return;
}
if(session[message_id - 1] === undefined) {
this.error = "AisDecode: Session is missing prior message part, cannot parse partial AIS message.";
return;
}
if(session.sequence_id !== sequence_id) {
this.error = "AisDecode: Session IDs do not match. Cannot recontruct AIS message.";
return;
}
} else {
session.formatter = nmea[0];
session.message_count = message_count;
session.sequence_id = sequence_id;
}
}
// extract binary payload and other usefull information from nmea paquet
this.payload = Buffer.from(nmea [5]);
this.msglen = this.payload.length;
this.channel = nmea[4]; // vhf channel A/B
if(message_count > 1) {
session[message_id] = {payload: this.payload, length: this.msglen};
// Not done building the session
if(message_id < message_count) return;
var payloads = [];
var len = 0;
for(var i = 1; i <= session.message_count; ++i) {
payloads.push(session[i].payload);
len += session[i].length;
}
this.payload = Buffer.concat(payloads, len);
this.msglen = this.payload.length;
}
// decode printable 6bit AIS/IEC binary format
for(var i = 0; i < this.msglen; i++) {
var byte = this.payload[i];
// check byte is not out of range
if ((byte < 0x30) || (byte > 0x77)) return;
if ((0x57 < byte) && (byte < 0x60)) return;
// move from printable char to wacky AIS/IEC 6 bit representation
byte += 0x28;
if(byte > 0x80) byte += 0x20;
else byte += 0x28;
this.bitarray[i]=byte;
}
this.aistype = this.GetInt (0,6);
this.repeat = this.GetInt (6,2);
this.immsi = this.GetInt (8,30);
this.mmsi = ("000000000" + this.immsi).slice(-9);
this.mmsikey = this.mmsi;
switch (this.aistype) {
case 1:
case 2:
case 3: // class A position report
this.class = 'A';
this.navstatus = this.GetInt( 38, 4);
var lon = this.GetInt(61, 28);
if (lon & 0x08000000 ) lon |= 0xf0000000;
lon = parseFloat (lon / 600000);
var lat = this.GetInt(89, 27);
if( lat & 0x04000000 ) lat |= 0xf8000000;
lat = parseFloat (lat / 600000);
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
this.valid = true;
} else this.valid = false;
this.rot = this.GetInt( 42, 8, true ) // Rate of turn
this.sog = this.GetInt( 50, 10) / 10; //speed over ground
this.cog = this.GetInt( 116, 12) / 10; //course over ground
this.hdg = parseFloat (this.GetInt( 128, 9)); //magnetic heading
this.utc = this.GetInt( 137, 6 );
this.smi = this.GetInt( 143, 2 );
break;
case 18: // class B position report
this.class = 'B';
this.status = -1; // Class B targets have no status. Enforce this...
var lon = this.GetInt(57, 28 );
if (lon & 0x08000000 ) lon |= 0xf0000000;
lon = parseFloat (lon / 600000);
var lat = this.GetInt(85, 27 );
if( lat & 0x04000000 ) lat |= 0xf8000000;
lat = parseFloat (lat / 600000);
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
this.valid = true;
} else this.valid = false;
this.sog = this.GetInt( 46, 10 ) / 10; //speed over ground
this.cog = this.GetInt( 112, 12) / 10; //course over ground
this.hdg = parseFloat (this.GetInt( 124, 9)); //magnetic heading
this.utc = this.GetInt( 134, 6 );
break;
case 19: // Extended class B position report
this.class = 'B';
this.status = -1; // Class B targets have no status. Enforce this...
var lon = this.GetInt(57, 28 );
if (lon & 0x08000000 ) lon |= 0xf0000000;
lon = parseFloat (lon / 600000);
var lat = this.GetInt(85, 27 );
if( lat & 0x04000000 ) lat |= 0xf8000000;
lat = parseFloat (lat / 600000);
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
this.valid = true;
} else this.valid = false;
this.sog = this.GetInt( 46, 10 ) / 10; //speed over ground
this.cog = this.GetInt( 112, 12) / 10; //course over ground
this.hdg = parseFloat (this.GetInt( 124, 9)); //magnetic heading
this.utc = this.GetInt( 133, 6 );
this.shipname = this.GetStr(143,120).trim();
this.cargo = this.GetInt(263,8);
this.dimA = this.GetInt(271, 9 );
this.dimB = this.GetInt(280, 9 );
this.dimC = this.GetInt(289, 6 );
this.dimD = this.GetInt(295, 6 );
this.length = this.dimA + this.dimB;
this.width = this.dimC + this.dimD;
break;
case 5:
this.class = 'A';
// Get the AIS Version indicator
// 0 = station compliant with Recommendation ITU-R M.1371-1
// 1 = station compliant with Recommendation ITU-R M.1371-3 (or later)
// 2 = station compliant with Recommendation ITU-R M.1371-5 (or later)
// 3 = station compliant with future editions
var AIS_version_indicator = this.GetInt(38,2);
if( AIS_version_indicator < 3 )
{
this.imo = this.GetInt(40,30);
this.callsign = this.GetStr(70,42).trim();
this.shipname = this.GetStr(112,120).trim();
this.cargo = this.GetInt(232,8);
this.dimA = this.GetInt(240,9);
this.dimB = this.GetInt(249,9);
this.dimC = this.GetInt(258,6);
this.dimD = this.GetInt(264,6);
this.etaMo = this.GetInt(274,4);
this.etaDay = this.GetInt(278,5);
this.etaHr = this.GetInt(283,5);
this.etaMin = this.GetInt(288,6);
this.draught = this.GetInt(294, 8 ) / 10.0;
this.destination = this.GetStr(302, 120).trim();
this.length = this.dimA + this.dimB;
this.width = this.dimC + this.dimD;
this.valid = true;
}
break;
case 24: // Vesel static information
this.class='B';
this.part = this.GetInt(38, 2 );
if (0 === this.part ) {
this.shipname = this.GetStr(40, 120).trim();
this.valid = true;
} else if ( this.part === 1) {
this.cargo = this.GetInt(40, 8 );
this.callsign = this.GetStr(90, 42).trim();
// 98 = auxiliary craft
if (parseInt(this.immsi/10000000) === 98) {
var mothership = this.GetInt (132, 30);
this.mothership = ("000000000" + mothership).slice(-9);
} else {
this.dimA = this.GetInt(132, 9 );
this.dimB = this.GetInt(141, 9 );
this.dimC = this.GetInt(150, 6 );
this.dimD = this.GetInt(156, 6 );
this.length = this.dimA + this.dimB;
this.width = this.dimC + this.dimD;
}
this.valid = true;
}
break;
case 4: // base station
case 11: // UTC/Date Response
this.class = '-';
var lon = this.GetInt(79, 28);
if (lon & 0x08000000 ) lon |= 0xf0000000;
lon = parseFloat (lon / 600000);
var lat = this.GetInt(107, 27);
if( lat & 0x04000000 ) lat |= 0xf8000000;
lat = parseFloat (lat / 600000);
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
this.valid = true;
} else this.valid = false;
break;
case 9: // sar aircraft
this.class = '-';
this.alt = this.GetInt(38, 12);
var lon = this.GetInt(61, 28);
if (lon & 0x08000000 ) lon |= 0xf0000000;
lon = parseFloat (lon / 600000);
var lat = this.GetInt(89, 27);
if( lat & 0x04000000 ) lat |= 0xf8000000;
lat = parseFloat (lat / 600000);
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
this.valid = true;
} else this.valid = false;
this.sog = parseFloat (this.GetInt( 50, 10 )); //speed over ground
this.cog = this.GetInt( 116, 12) / 10; //course over ground
break;
case 21: // aid to navigation
this.class = '-';
this.aidtype = this.GetInt(38, 5);
this.shipname = this.GetStr(43, 120).trim();
var lon = this.GetInt(164, 28);
if (lon & 0x08000000 ) lon |= 0xf0000000;
lon = parseFloat (lon / 600000);
var lat = this.GetInt(192, 27);
if( lat & 0x04000000 ) lat |= 0xf8000000;
lat = parseFloat (lat / 600000);
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
this.valid = true;
} else this.valid = false;
this.dimA = this.GetInt(219, 9 );
this.dimB = this.GetInt(228, 9 );
this.dimC = this.GetInt(237, 6 );
this.dimD = this.GetInt(243, 6 );
this.length = this.dimA + this.dimB;
this.width = this.dimC + this.dimD;
this.utc = this.GetInt(253, 6);
this.offpos = this.GetInt(259, 1);
this.virtual = this.GetInt(269, 1);
var len = parseInt(( ( this.bitarray.length - 272 /6 ) / 6 ) * 6)*6;
this.txt = this.GetStr(272 , len).trim();
break;
case 14: // text msg
this.class = '-';
if (this.bitarray.length > 40/6) {
var len = parseInt(( ( this.bitarray.length - 40/6 ) / 6 ) * 6)*6;
this.txt = this.GetStr(40, len).trim();
this.valid = true;
}
break;
case 8: // Binary Broadcast Message
this.dac = this.GetInt(40, 10 );
this.fid = this.GetInt(50, 6 );
// Inland ship static and voyage related data
if (this.dac === 200 && this.fid === 10 ) {
this.class = '-';
this.ENI = this.GetStr(56,48).trim();
this.length = parseFloat(this.GetInt(104, 13 )) /10.;
this.width = parseFloat(this.GetInt(117, 10 )) /10.;
this.draught = parseFloat(this.GetInt(144, 11 )) / 100.0;
this.shiptypeERI = this.GetInt(127, 14 );
this.valid = true;
}
// meteorological and hydrographic data
else if (this.dac === 1 && this.fid === 31 ) {
// https://academy.iala-aism.org/asm/meteorological-hydrographic-data/
this.class = '-';
var lon = this.GetInt(56, 25);
if (lon & 0x01000000) lon |= 0xfe000000;
lon = parseFloat (lon / 60000);
var lat = this.GetInt(81, 24);
if (lat & 0x00800000) lat |= 0xff000000;
lat = parseFloat (lat / 60000);
this.utcday = parseInt(this.GetInt(106, 5));
this.utchour = parseInt(this.GetInt(111, 5));
this.utcminute = parseInt(this.GetInt(116, 6));
var avgwindspd = parseInt(this.GetInt(122, 7));
if (avgwindspd != 127) {
this.avgwindspd = avgwindspd;
}
var windgust = parseInt(this.GetInt(129, 7));
if (windgust != 127) {
this.windgust = windgust;
}
var winddir = parseInt(this.GetInt(136, 9));
if (winddir < 360) {
this.winddir = winddir;
}
var windgustdir = parseInt(this.GetInt(145, 9));
if (windgustdir < 360) {
this.windgustdir = windgustdir;
}
var airtemp = parseInt(this.GetInt(154, 11, 1));
if (airtemp < 601 && airtemp > -601){
this.airtemp = airtemp / 10.0;
}
var relhumid = parseInt(this.GetInt(165, 7));
if (relhumid < 101) {
this.relhumid = relhumid;
}
var dewpoint = parseInt(this.GetInt(172, 10, 1));
if (dewpoint < 501 && dewpoint > -201){
this.dewpoint = dewpoint / 10.0;
}
var airpress = parseInt(this.GetInt(182, 9));
if (airpress < 401) {
this.airpress = airpress + 799;
}
var airpressten = parseInt(this.GetInt(191, 2));
if (airpressten < 3) {
this.airpressten = airpressten;
}
var horvisib = parseInt(this.GetInt(194, 7));
if (horvisib < 127) {
this.horvisib = horvisib / 10.0;
var horvisibrange = parseInt(this.GetInt(193, 1));
this.horvisibrange = horvisibrange === 1;
}
var waterlevel = parseInt(this.GetInt(201, 12));
if (waterlevel < 4001) {
this.waterlevel = (waterlevel - 1000) / 100.0;;
}
var waterlevelten = parseInt(this.GetInt(213, 2));
if (waterlevelten < 3) {
this.waterlevelten = waterlevelten;
}
var surfcurrspd = parseInt(this.GetInt(215, 8));
if (surfcurrspd < 252) {
this.surfcurrspd = surfcurrspd / 10.0;;
}
var surfcurrdir = parseInt(this.GetInt(223, 9));
if (surfcurrdir < 360) {
this.surfcurrdir = surfcurrdir;
}
var signwavewhgt = parseInt(this.GetInt(276, 8));
if (signwavewhgt < 252) {
this.signwavewhgt = signwavewhgt / 10.0;
}
var waveperiod = parseInt(this.GetInt(284, 6));
if (waveperiod < 61) {
this.waveperiod = waveperiod;
}
var wavedir = parseInt(this.GetInt(290, 9));
if (wavedir < 360) {
this.wavedir = wavedir;
}
var swellhgt = parseInt(this.GetInt(299, 8));
if (swellhgt < 252) {
this.swellhgt = swellhgt / 10.0;
}
var swellperiod = parseInt(this.GetInt(307, 6));
if (swellperiod < 61) {
this.swellperiod = swellperiod;
}
var swelldir = parseInt(this.GetInt(313, 9));
if (swelldir < 360) {
this.swelldir = swelldir;
}
var seastate = parseInt(this.GetInt(322, 4));
if (seastate < 13) {
this.seastate = seastate;
}
var watertemp = parseInt(this.GetInt(326, 10, 1));
if (watertemp < 501 && watertemp > -101){
this.watertemp = watertemp / 10.0;
}
var precipitation = parseInt(this.GetInt(336, 3));
if (precipitation < 7) {
this.precipitation = precipitation;
}
var salinity = parseInt(this.GetInt(339, 9));
if (salinity < 502) {
this.salinity = salinity / 10.0;
}
var ice = parseInt(this.GetInt(348, 2));
if (ice < 2) {
this.ice = ice;
}
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
var latPart = ("000000" + parseInt(("000" + (lat % 1).toFixed(3).slice(-3)).slice(-3), 10)).slice(-3);
var lonPart = ("000000" + parseInt(("000" + (lon % 1).toFixed(3).slice(-3)).slice(-3), 10)).slice(-3);
this.mmsikey = this.mmsi + ':' + latPart + lonPart;
this.valid = true;
} else this.valid = false;
}
// meteorological and hydrographic data (Deprecated)
else if (this.dac === 1 && this.fid === 11 ) {
// https://academy.iala-aism.org/asm/metreorological-hydrological-data-2/
this.class = '-';
var lon = this.GetInt(80, 25);
if (lon & 0x01000000) lon |= 0xfe000000;
lon = parseFloat (lon / 60000);
var lat = this.GetInt(56, 24);
if (lat & 0x00800000) lat |= 0xff000000;
lat = parseFloat (lat / 60000);
this.utcday = parseInt(this.GetInt(105, 5));
this.utchour = parseInt(this.GetInt(110, 5));
this.utcminute = parseInt(this.GetInt(115, 6));
var avgwindspd = parseInt(this.GetInt(121, 7));
if (avgwindspd != 127) {
this.avgwindspd = avgwindspd;
}
var windgust = parseInt(this.GetInt(128, 7));
if (windgust != 127) {
this.windgust = windgust;
}
var winddir = parseInt(this.GetInt(135, 9));
if (winddir < 360) {
this.winddir = winddir;
}
var windgustdir = parseInt(this.GetInt(144, 9));
if (windgustdir < 360) {
this.windgustdir = windgustdir;
}
var airtemp = parseInt(this.GetInt(153, 11, 1)) - 600;
if (airtemp < 601 && airtemp > -601){
this.airtemp = airtemp / 10.0;
}
var relhumid = parseInt(this.GetInt(164, 7));
if (relhumid < 101) {
this.relhumid = relhumid;
}
var dewpoint = parseInt(this.GetInt(171, 10, 1)) - 200;
if (dewpoint < 501 && dewpoint > -201){
this.dewpoint = dewpoint / 10.0;
}
var airpress = parseInt(this.GetInt(181, 9));
if (airpress < 401) {
this.airpress = airpress + 799;
}
var airpressten = parseInt(this.GetInt(190, 2));
if (airpressten < 3) {
this.airpressten = airpressten;
}
var horvisib = parseInt(this.GetInt(192, 8));
if (horvisib != 255) {
this.horvisib = horvisib / 10.0;;
}
var waterlevel = parseInt(this.GetInt(200, 9));
if (waterlevel < 4001) {
this.waterlevel = (waterlevel - 1000) / 100.0;;
}
var waterlevelten = parseInt(this.GetInt(209, 2));
if (waterlevelten < 3) {
this.waterlevelten = waterlevelten;
}
var surfcurrspd = parseInt(this.GetInt(211, 8));
if (surfcurrspd < 252) {
this.surfcurrspd = surfcurrspd / 10.0;;
}
var surfcurrdir = parseInt(this.GetInt(219, 9));
if (surfcurrdir < 360) {
this.surfcurrdir = surfcurrdir;
}
var signwavewhgt = parseInt(this.GetInt(272, 8));
if (signwavewhgt < 252) {
this.signwavewhgt = signwavewhgt / 10.0;
}
var waveperiod = parseInt(this.GetInt(280, 6));
if (waveperiod < 61) {
this.waveperiod = waveperiod;
}
var wavedir = parseInt(this.GetInt(286, 9));
if (wavedir < 360) {
this.wavedir = wavedir;
}
var swellhgt = parseInt(this.GetInt(295, 8));
if (swellhgt < 252) {
this.swellhgt = swellhgt / 10.0;
}
var swellperiod = parseInt(this.GetInt(303, 6));
if (swellperiod < 61) {
this.swellperiod = swellperiod;
}
var swelldir = parseInt(this.GetInt(309, 9));
if (swelldir < 360) {
this.swelldir = swelldir;
}
var seastate = parseInt(this.GetInt(318, 4));
if (seastate < 13) {
this.seastate = seastate;
}
var watertemp = parseInt(this.GetInt(322, 10, 1));
if (watertemp < 501 && watertemp > -101){
this.watertemp = watertemp / 10.0;
}
var precipitation = parseInt(this.GetInt(332, 3));
if (precipitation < 7) {
this.precipitation = precipitation;
}
var salinity = parseInt(this.GetInt(335, 9));
if (salinity < 502) {
this.salinity = salinity / 10.0;
}
var ice = parseInt(this.GetInt(344, 2));
if (ice < 2) {
this.ice = ice;
}
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
var latPart = ("000000" + parseInt(("000" + (lat % 1).toFixed(3).slice(-3)).slice(-3), 10)).slice(-3);
var lonPart = ("000000" + parseInt(("000" + (lon % 1).toFixed(3).slice(-3)).slice(-3), 10)).slice(-3);
this.mmsikey = this.mmsi + ':' + latPart + lonPart;
this.valid = true;
} else this.valid = false;
}
// meteorological and hydrographic data
else if (this.dac === 367 && this.fid === 33 ) {
// https://www.e-navigation.nl/sites/default/files/asm_files/em_version_release_3-23mar15_0.pdf
this.class = '-';
var len = Math.floor((this.msglen * 6)/112);
for(var i=0 ; i<len ; i++) {
this.reporttype = parseInt(this.GetInt(56 + (112*i), 4));
this.utcday = parseInt(this.GetInt(60, 5));
this.utchour = parseInt(this.GetInt(65, 5));
this.utcminute = parseInt(this.GetInt(70, 6));
this.siteid = parseInt(this.GetInt(76, 6));
this.mmsikey = this.mmsi + ':' + this.siteid;
if (this.reporttype === 0) {
var msgversion = parseInt(this.GetInt(56 + (112*i) + 27, 6));
if (msgversion === 0 || msgversion > 15) break;
var lon = this.GetInt(56 + (112*i) + 33, 28);
if (lon & 0x08000000) lon |= 0xf0000000;
lon = parseFloat (lon / 600000);
var lat = this.GetInt(56 + (112*i) + 61, 27);
if (lat & 0x04000000) lat |= 0xf8000000;
lat = parseFloat (lat / 600000);
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
this.valid = true;
} else this.valid = false;
}
else if (this.reporttype === 1) {
this.shipname = this.GetStr(56 + (112*i) + 27, 84).trim();
this.valid = true;
}
else if (this.reporttype === 2) {
var avgwindspd = parseInt(this.GetInt(56 + (112*i) + 27, 7));
if (avgwindspd < 122) {
this.avgwindspd = avgwindspd;
}
var windgust = parseInt(this.GetInt(56 + (112*i) + 34, 7));
if (windgust < 122) {
this.windgust = windgust;
}
var winddir = parseInt(this.GetInt(56 + (112*i) + 41, 9));
if (winddir < 360) {
this.winddir = winddir;
}
var windgustdir = parseInt(this.GetInt(56 + (112*i) + 50, 9));
if (windgustdir < 360) {
this.windgustdir = windgustdir;
}
this.valid = true;
}
else if (this.reporttype === 3) {
var descr = parseInt(this.GetInt(56 + (112*i) + 50, 3));
if (descr === 1 || descr === 2) {
var waterlevel = parseInt(this.GetInt(56 + (112*i) + 27, 16, 1));
if (waterlevel > -32768) {
this.waterlevel = waterlevel / 100.0;;
}
var waterlevelten = parseInt(this.GetInt(56 + (112*i) + 43, 2));
if (waterlevelten < 3) {
this.waterlevelten = (waterlevelten === 0 ? 2 : (waterlevelten === 2 ? 0 : 1));
}
this.valid = true;
}
}
else if (this.reporttype === 9) {
var descr = parseInt(this.GetInt(56 + (112*i) + 38, 3));
if (descr === 1 || descr === 2) {
var airtemp = parseInt(this.GetInt(56 + (112*i) + 27, 11, 1));
if (airtemp < 601 && airtemp > -601){
this.airtemp = airtemp / 10.0;
}
}
descr = parseInt(this.GetInt(56 + (112*i) + 61, 3));
if (descr === 1 || descr === 2) {
var horvisib = parseInt(this.GetInt(56 + (112*i) + 43, 8));
if (horvisib < 242) {
this.horvisib = horvisib / 10.0;;
if (horvisib === 241){
this.horvisibrange = true;
}
else {
this.horvisibrange = false;
}
}
var dewpoint = parseInt(this.GetInt(56 + (112*i) + 51, 10, 1));
if (dewpoint < 501 && dewpoint > -201){
this.dewpoint = dewpoint / 10.0;
}
}
descr = parseInt(this.GetInt(56 + (112*i) + 75, 3));
if (descr === 1 || descr === 2) {
var airpress = parseInt(this.GetInt(56 + (112*i) + 64, 9));
if (airpress < 401) {
this.airpress = airpress + 799;
}
var airpressten = parseInt(this.GetInt(56 + (112*i) + 73, 2));
if (airpressten < 3) {
this.airpressten = airpressten;
}
}
var salinity = parseInt(this.GetInt(56 + (112*i) + 78, 9));
if (salinity < 502) {
this.salinity = salinity / 10.0;
}
this.valid = true;
}
else {
console.log (' -->msg-08 ' + i + ' report not found '+ this.reporttype);
}
}
}
else {
if (DEBUG) {
console.log ('---- type=%d %s dac=%d fid=%d %s', this.aistype, this.mmsi, dac, fid, input);
}
}
break;
case 27: // Long Range AIS Broadcast message
this.class = '-';
this.navstatus = this.GetInt( 40, 4);
var lon = this.GetInt(44, 18 );
lon = parseFloat (lon) / 600;
var lat = this.GetInt(62, 17 );
lat = parseFloat (lat) / 600;
if( ( lon <= 180. ) && ( lat <= 90. ) ) {
this.lon = lon;
this.lat = lat;
this.valid = true;
} else this.valid = false;
this.sog = this.GetInt( 79, 6 ) ; //speed over ground
this.cog = this.GetInt( 85, 9); //course over ground
break;
default:
if (DEBUG) {
console.log ('---- type=%d %s %s -> %s', this.aistype, this.Getaistype(this.aistype), this.mmsi, input);
}
break;
}
}
// Validate message checksum
AisDecode.prototype.validateChecksum = function(input) {
if (typeof input === "string") {
var loc1 = input.indexOf("!");
var loc2 = input.indexOf("*");
if (loc1 === 0 && loc2 > 0) {
var body = input.substring(1, loc2);
var checksum = input.substring(loc2 + 1).toUpperCase();
for (var sum = 0, i = 0; i < body.length; i++) {
sum ^= body.charCodeAt(i); //xor based checksum
}
var hex = sum.toString(16).toUpperCase();
if (hex.length === 1) hex = '0' + hex; //single digit hex needs preceding 0, '0F'
return (checksum === hex);
}
}
return false;
};
// Extract an integer sign or unsigned from payload
AisDecode.prototype.GetInt= function (start, len, signed) {
var acc = 0;
var cp, cx,c0, cs;
for(var i=0 ; i<len ; i++)
{
acc = acc << 1;
cp = parseInt ((start + i) / 6);
cx = this.bitarray[cp];
cs = 5 - ((start + i) % 6);
c0 = (cx >> cs) & 1;
if (i === 0 && signed && c0) { // if signed value and first bit is 1, pad with 1's
acc = ~acc;
}
acc |= c0;
//console.log ('**** bitarray[%d]=cx=%s i=%d cs=%d co=%s acc=%s'
//,cp , this.bitarray[cp].toString(2), i, cs, c0.toString(2),acc.toString(2));
}
//console.log ('---- start=%d len=%d acc=%s acc=%d', start, len , acc.toString(2), acc);
return acc;
};
// Extract a string from payload [1st bits is index 0]
AisDecode.prototype.GetStr= function(start, len) {
// extended message are not supported
if (this.bitarray.length < (start + len) /6) {
//console.log ("AisDecode: ext msg not implemented GetStr(%d,%d)", start, len);
len = parseInt(( ( this.bitarray.length - start/6 ) / 6 ) * 6)*6;
}
// messages in the wild sometimes produce a negative len which will cause a buffer range error
// exception, stating size argument must not be negative. This occurs in the new Buffer() below.
if (len < 0) {
return '';
}
//char temp_str[85];
var buffer = Buffer.alloc(len/6);
var cp, cx, cs,c0;
var acc = 0;
var k = 0;
var i = 0;
while(i < len)
{
acc=0;
for(var j=0 ; j<6 ; j++)
{
acc = acc << 1;
cp = parseInt ((start + i) / 6);
cx = this.bitarray[cp];
cs = 5 - ((start + i) % 6);
c0 = (cx >> (5 - ((start + i) % 6))) & 1;
acc |= c0;
i++;
}
buffer[k] = acc; // opencpn
if(acc < 0x20) buffer[k] += 0x40;
else buffer[k] = acc; // opencpn enfoce (acc & 0x3f) ???
if ( buffer[k] === 0x40) break; // name end with '@'
k++;
}
return (buffer.toString ('utf8',0, k));