Join Date: Sep 2003
Location: Ubatuba,SP,Brazil (Ex Norway)
Boat: (Ex) Alu. 60' yacht-"Eight Bells"
Re: ARPA Target
Experimentally,coastal stations also include radar targets within their range and transmit their positions together with AIS
targets over the internet
, which can be accessed by f.ex. Marine
Traffic URL/software. OK, if you have a long range WiFi antenna
Radar is today the main sensor of the VTS to detect a ship.
The VTS radar has almost the same errors in range and bearing
resolution as all other radar’s, although it has a known position
and is North oriented without the errors of a compass involved.
The limitations, of the ARPA radar to track ships due to target
swap to land, beacons, bridges and other ships, makes the tracking
facility in the ARPA rather limited.
VTS’s are today limited to track ships, for instance, in a bay
or when approaching a harbour from sea. There is a require-
ment for improving of the VTS to be able to:
A) Cover areas where radar coverage is almost impossible to
achieve, like rivers and archipelagos
B) Identify radar blips on the VTS radar automatically.
C) Interrogate ships for information regarding type of cargo
D) Track with a high up date rate, the ferry going between two
ports in the bay or a river continuously, without needing to
do it every time the radar tracking has swapped to another
target or, when the ferry has been moored to a pier or passed
too close to a beacon or a passing ship
* Know which port a ship is bound for.
* Know the size and the draft of ships in the vicinity.
* Detect a change in a ship’s heading almost in real time.
* Identify slowly moving targets, like log rafts, sounding arrays
etc., which are unable to take rapid evasive actions.
The only AIS solution, that could solve all the requirements
of the VTS, is a high update rate, mode AIS, with interrogating
The establishment of a landbased AIS reception network,
may actually mitigate the need for VTS in some areas. The cost
of installing and maintaining an AIS network is minute com-
pared to a VTS radar net-work.
"And all I ask is a tall ship and a star to steer her by."