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):

DAC or VPFI:

FI / Message ID:

Technical point of contact:

IALA

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

State:

proposal

Number of slots (max):

FEC:

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