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ASM message

Introduction/Additional information: 

This VDE Protocol Format may be used to embed multiple ASM functional messages using the ASM standard header, to utilize the higher bandwidth capabilities of VDE-TER and VDE-SAT and/or to offload ASM traffic from the AIS channels

Permitted as from: 
01/12/2022
Registrant: 
IALA
Physical link: 
VDE-TER
VDE-SAT
Message number (0=VDES-VDE): 
0
DAC or VPFI: 
2
FI / Message ID: 
4
Technical point of contact: 

IALA

G1117-Ed3.0-VHF-Data-Exchange-System-VDES-Overview

State: 
proposal
Number of slots (max): 
1
FEC: 
No
Last modified: 
29/03/2023 - 15:09
Details: 

Parameter

Number of bits

Description

VPFI

16

2

Message ID

16

4

n

8

number of encapsulated ASMs

0: unused value

1-255: valid values

Length of ASM [0]

16

Number of bits of ASM [0]

ASM data [0]  (first ASM)

variable

16 bit: Application Identifier[0], see ITU-R M.1371-5, Annex 5 m[0] bits: ASM Data Content [0]

Length of ASM [1]

16

Number of bits of ASM [1]

ASM data [1]  (second ASM)

variable

16 bit: Application Identifier[1], see ITU-R M.1371-5, Annex 5 m[0] bits: ASM Data Content [1]

…

…

…

Length of ASM [n-1]

16

Number of bits of ASM [n-1]

ASM data [n-1] (last ASM)

variable

16 bit: Application Identifier[n-1], see ITU-R M.1371-5, Annex 5 m[0] bits: ASM Data Content [n-1]

Valid until

32

Unsigned integer number of seconds after the 1st of January

1970 00:00:00 UTC. After the 19th of January 2038 03:14:07

UTC, the number is the number of seconds after this new date (wraps around);

To avoid replay attacks, this value shall be used by the receiving application to verify the validity of the data.

Signature

512

Signature over above data, applied over all bits from the start of the VPFI field to the end of the last bit, just before the signature, generated as described for the terrestrial bulletin board, see ITU-R M.2092-1, Annex 4, §4.15

Total number of bits

Variable size