e-Navigation Netherlands
Published on e-Navigation Netherlands (https://www.e-navigation.nl)

Home > Position Report Payload

Introduction/Additional information: 

The EAIS Position Report Payload format is intended to mirror ITU-R M.1371-5 Message 1 Position Reports format. The table contained here is informational. Implementers should refer back to ITU-R M.1371-[current revision] for most up to date bit usage and descriptions. The EAIS Position Report Payload prior to encryption without bit stuffing is 184 bits in length. Conforming to the AES Encryption scheme with a 128-bit cipher key, the encrypted part of the payload then effectively becomes 256 bits in length to create blocks of 128 bits. The FID 56 position report shall be transmitted once every 30 seconds when the unit has registered a speed over ground (SOG) of less than 3 knots for more than 3 minutes and once every 15 seconds when SOG is 3 knots or greater.

Permitted as from: 
04/06/2014
Not to be used after: 
20/04/2017
Registrant: 
USCG
Physical link: 
AIS
Message number (0=VDES-VDE): 
8
DAC or VPFI: 
366
FI / Message ID: 
56
State: 
deprecated
State link: 
Situation Report (SITREP) for Vessels and Aircraft (encrypted) [1]
Number of slots (max): 
3
Last modified: 
29/01/2021 - 23:19
Details: 
NOTE: The Message 1 two (2) bit REPEAT INDICATOR field, normally located between FUNCTION ID and USER ID, is omitted in the EAIS Position Report Payload (See below).

 

Parameter

Number of bits

Description

Encryption Status

DAC

10

Identifier for this message: 366

Unencrypted

Function ID

6

Function Identifier: 56

Unencrypted

Repeat Indicator

0

Not present in EAIS Position Report Payload

no bits

User ID

30

MMSI number.

AES encrypted

 

 

 

 

 

 

 

 

 

 

 

Navigational Status

 

 

 

 

 

 

 

 

 

 

 

 

4

0 = under way using engine 1 = at anchor

2 = not under command

3 = restricted maneuverability 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 ships carrying DG, HS, or MP, or IMO hazard or pollutant category C, high speed craft (HSC),

10 = reserved for future amendment of navigational status for ships carrying dangerous goods (DG), harmful substances (HS) or marine pollutants (MP), or IMO hazard or pollutant category A, wing in ground (WIG); 11 = power driven vessel towing astern (regional use),

12 = power-driven vessel pushing ahead or towing alongside (regional use);

13 = reserved for future use,

14 = AIS-SART (active), MOB-AIS, EPIRB- AIS

15 = undefined = default (also used by AIS- SART, MOB-AIS and EPIRBAIS under test)

 

 

 

 

 

 

 

 

 

 

 

 

AES encrypted

 

 

Parameter

Number

of bits

Description

Encryption

Status

 

 

 

 

 

 

 

Rate of turn ROTAIS

 

 

 

 

 

 

 

 

8

0 to +126 = turning right at up to 708° per min or higher

0 to –126 = turning left at up to 708° per min or higher

Values between 0 and 708° per min coded by ROTAIS = 4.733 SQRT(ROTsensor) degrees per min

where ROTsensor is the Rate of Turn as input by an external Rate of Turn

Indicator (TI). ROTAIS is rounded to the nearest integer value.

+127 = turning right at more than 5° per 30 s (No TI available)

–127 = turning left at more than 5° per 30 s (No TI available)

–128 (80 hex) indicates no turn information available (default).

ROT data should not be derived from COG information.

 

 

 

 

 

 

 

 

AES encrypted

 

SOG

 

10

Speed over ground in 1/10 knot steps (0-102.2 knots)

1023 = not available, 1022 = 102.2 knots or higher.

 

AES encrypted

 

Position Accuracy

 

1

The position accuracy (PA) flag 1 = high (≤ 10 m)

0 = low (>10 m)

0 = default

 

AES encrypted

 

 

Longitude

 

 

28

Longitude in 1/10 000 min (±180 degrees, East = positive,

West = negative.

181 degrees (6791AC0 hex) = not available = default)

 

 

AES encrypted

 

 

Latitude

 

 

27

Latitude in 1/10 000 min (±90 degrees, North

= positive,

South = negative,

91 degrees (3412140 hex) = not available = default)

 

 

AES encrypted

 

COG

 

12

Course over ground in 1/10° (0-3599). 3600 (E10 hex) = not available =

default;

3 601 – 4 095 should not be used.

 

AES encrypted

True Heading

9

Degrees (0-359) (511 indicates not available = default).

AES encrypted

 

 

Time Stamp

 

 

 

6

UTC second when the report was generated by the electronic position system (EPFS) (0- 59, or 60 if time stamp is not available, which should also be the default value, or 61 if positioning system is in manual input mode, or 62 if electronic position fixing system operates

in estimated (dead reckoning) mode, or 63 if the positioning system is inoperative)

 

 

 

AES encrypted

 

 

Parameter

Number

of bits

Description

Encryption

Status

 

Special maneuver indicator

 

 

2

0 = not available = default

1 = not engaged in special maneuver 2 = engaged in special maneuver

(i.e. regional passing arrangement on Inland Waterway)

 

 

AES encrypted

Spare

3

Not used. Should be set to zero.

AES encrypted

 

RAIM-Flag

 

1

RAIM (Receiver Autonomous Integrity Monitoring) flag of Electronic Position Fixing Device; 0 = RAIM not in use = default; 1 = RAIM in use)

 

AES encrypted

 

Communication State

 

19

MSG ID 1 & 2 = SOTDMA communication state as described in 1371-5, Annex 2

MSG ID 3 ITDMA communication state as described in 1371-5, Annex 2

 

AES encrypted

Checksum

8

Exclusive OR (XOR) 8-bit

AES encrypted

 

Stuffed bits

 

88

Stuffed bits are inserted so that the number of bits in the encrypted field is a multiple of 128 bits (256 for this message); set to zero.

 

AES encrypted

TOTAL

272

16 unencrypted bits plus 256 encrypted bits

 

Attachment: 
PDF icon epic-15-05-29-uscg-foia-20151030-production-2.pdf [2]

Source URL (modified on 29/01/2021 - 23:19):https://www.e-navigation.nl/content/position-report-payload

Links
[1] https://www.e-navigation.nl/content/situation-report-sitrep-vessels-and-aircraft-encrypted [2] https://www.e-navigation.nl/sites/default/files/asm_files/epic-15-05-29-uscg-foia-20151030-production-2.pdf