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 radars, 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, make
the tracking facility in the ARPA rather limited.
VTSs are today limited to track ships, for instance,
in a bay or when approaching a harbour
from sea. There is a requirement for improving
VTS to be able to: