Kongsberg Seatex AIS 100 Instruction Manual page 75

Seatex AIS 100 Instruction Manual, rev. 5
NOTE 3
NOTE 4
NOTE 5
NOTE 1
NOTE 2
The AIS message reception channel is indicated as either "A" or "B."
This channel indication is relative to the operating conditions of the
AIS when the packet is received. This field shall be null when the
channel identification is not provided. The VHF channel numbers for
channels "A" and "B" are obtained by using an ACA-sentence "query"
of the AIS.
The maximum string length of encapsulation is limited such that the
total number of sentence characters does not exceed 82. This field
supports a maximum of 62 valid characters for a message transferred
using multiple sentences, and 63 valid characters for a message using
a single sentence.
To encapsulate, the number of binary bits must be a multiple of six. If
it is not, one to five "fill bits" are added. This parameter indicates the
number of bits that were added to the last 6-bit coded character. This
value shall be set to zero when no "fill bits" have been added. This
cannot be a null field.
VDO – VHF Data-link Own-vessel message
This sentence is used to provide the information assembled for
broadcast by the AIS. It uses the six-bit field type for encapsulation.
The sentence uses the same structure as the VDM sentence formatter.
The length of an ITU-R M.1371 message may be long and may
require the use of multiple sentences. The first field specifies the total
number of sentences used for a message, minimum value 1. The
second field identifies the order of this sentence in the message,
minimum value 1. These cannot be null fields.
The Sequential message identifier provides a message identification
number from 0 to 9 that is sequentially assigned and is incremented
for each new multi-sentence message. The count resets to 0 after 9 is
used. For a message requiring multiple sentences, each sentence of the
message contains the same sequential message identification number.
It is used to identify the sentences containing portions of the same
message. This allows for the possibility that other sentences might be
67
External interfaces