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Text using UTF-8 encoding

Introduction/Additional information: 

This VDE Protocol Format shall be used by applications that use VDE stations to transfer UTF-8 encoded text. The text can be sent over VDE-TER or VDE-SAT as broadcast or addressed message. The parameter, “acknowledge required flag”, should be set to 0 when broadcast is used.

When long text strings are sub-divided, an 11-bit “text sequence number” is used. The text sequence number is used by the originating application to sub-divide the text and by the recipient application to re-assemble the text. The text sequence numbers for each sub-division should be selected to be contiguous and always increasing (110, 111, 112, …). If long text strings are being transferred, the text sequence numbers should be chosen to associate correctly the sub-divided text with the correct text strings.

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: 
1
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 - 15:07
Details: 

Parameter

Number of bits

Description

VPFI

16

2

Message ID

16

1

Acknowledge required flag

1

1 = reply is required, optional for addressed messages and not used for broadcast messages

0 = reply is not required, optional for an addressed message and required for broadcast messages 

Sequence number

2

0 – 3; see ITU-R M.1371-5, § 5.3.1, Annex 2

Text sequence number

11

Sequence number to be incremented by the application.

All zeros indicates that sequence numbers are not being used 

Last text in sequence

1

0: more text will follow

1: this is the last message in a sequence

Spare bits

3

Byte boundary padding, bit values set to 0;

Text string

VDE-TER: 8-8000

VDE-SAT: 8-

80000

UTF-8 encoded text (see ISO/IEC 10646:2021).

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 together with the signature field.

Signature

512

Signature over above data, applied over all bits from the start of the VPI 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 application data bits

variable