This section should give a short introduction
to the AIS system display of information
and available options the automatic
identification system abbreviated a is
is a transponder system designed for the
exchange of information between ships
and between ship and Shore stations
information may also be exchanged
between ships and a is equipped
aircraft's regulation 19 safety of life
at sea su las chapter 5 requires a is to
be fitted on certain ships through a
phased implementation period spanning
from first of july 2002 to july two
thousand eight in addition specific
vessel types warships ships operated by
governments etc are not required to
carry a is also small vessels leisure
craft fishing vessels etc and certain
other vessels are exempt from carrying a
is some water ways such as the panama
canal and the st. Lawrence Seaway
already require all ships operating in
their waters to be equipped with a is
users of a is should always bear in mind
that information provided by AIS may not
give a complete picture of the shipping
traffic in their vicinity
there are many reasons why the AIS may
not give a correct picture of the
traffic such as a is malfunction a is
switched off
no carriage requirement etc this is why
is is not an equipment that is included
as part of the collision regulations in
other ways then by all means a is is
intended to enhance safety of life at
sea safety and efficiency
of navigation and protection of the
marine environment the purpose of a is
is to help identify vessels assists and
target tracking simplify information
exchange and provide additional
information to boost situation awareness
the AIS is based on a technology called
self-organized time division multiple
access or sotd am a which allows for
seamless operation worldwide this
concept basically utilizes known
technologies that combines them in a
unique way the AIS transponder
broadcasts the data fully automatically
to other ships within reach the AIS
transponders forms a cell where the own
unit always forms the center of such
sell three main components are combined
in a single unit a transponder the
transponder is fully automatic and
should be kept in operation at all times
except where international agreements
rules or standards provide for the
protection of navigational information
the AIS transponders consists of a very
high frequency VHF radio unit global
positioning system gps receiver computer
keyboard and display unit the gps
provides position and navigational data
computer packs this information together
with information about the vessels speed
name callsign heading course and speed
over ground etc this information is
transmitted at short intervals via VHF
radio two other ships and orlando base
stations within the hf radio range if
all ships within VHF range are equipped
with a is
is the result is that everybody can see
everybody fixed or static information is
entered into the AIS during installation
this information need only be changed if
the shift changes name or undergoes
major conversion from one ship type to
another
dynamic information which apart from
navigational status information is
automatically updated by the ship's
sensors connected to a is
voyage related information which might
need to be manually updated during the
voyage
hey is information may be displayed is
alpha numeric information and/or
graphically on radar arpa practice or
other relevant systems present
international maritime organization i am
o.k is requirement allows display of a
is information as alpha numeric
information only
this display is referred to as the
minimum display the minimum mandated
display provides not less than three
lines of data consisting of bearing
range and name of selected ship other
data about the ship can be displayed by
the horizontal scrolling of data but the
scrolling of bearing and range is not
possible vertical scrolling will show
all other ships known to a is instead of
minimum keyboard display mkd most
manufacturers provide what they call
enhanced minimum keyboard display which
provides a graphical presentation of a
is targets where a is information is
used with a graphical display the
following target options are available
for display sleeping target activated
target selected target dangerous target
and lost target sleeping target
indicates only the presence of the
vessel equipped with a is in a certain
location
no additional information is presented
until activated thus avoiding
information overload if the user wants
to know more about a vessel's motion he
has to activate the sleeping target so
that the display shows available target
information available target information
will be a speed vector showing
calculated target speed and course over
ground target heading rate of turn our
OT indication if available
to display actually initiated course
changes if the operator wants detailed
information on a target he may select it
with a pointing device data received as
well as the calculated closest point of
approach cpa and time to cba TCPA values
will be shown in an alphanumeric window
the special navigation status will also
be indicated in the alphanumeric data
field and not together with the target
directly if an AIS target is calculated
to pass preset cpa and TCPA limits it
will be classified and displayed as a
dangerous target and an alarm will be
given at the time of production of this
cbt no international standards for a is
target symbols were established IMO is
currently working on the harmonization
of ARPA activist and a is graphical
target symbols performance standards for
a is were adopted in 1998 the regulation
requires the AIS shall provide
information including the ship's
identity type position course speed
navigational status and other safety
related information automatically to
appropriately equipped short stations
other ships and aircraft automatically
receive such information from similarly
equipped ships monitor and track ships
and exchange data with sure base
facilities