214
12 Radar Systems of Maritime Transport
The direction resolution probability of the station at 0.8 probability is not more
than 2.2°, and the limit of the permissible measuring error of directions is 0.8°.
Guard zone—the auto-lock-on zone for auto-tracking can be quickly switched
on and installed at an angle from 0.7 to 360°, in width up to 4 nautical miles, at a
distance of up to 24 nautical miles. The guard zone is effective if the boundaries of
the zone are observed on the screen within the included range scale. The sound signal
is given automatically when the target enters the zone and during its auto-lock-on
for auto-tracking (target acquisition).
The built-in automatic radar plotting system (ARPS) provides:
• automatic or manual lock-on/target acquisition of up to 30 targets for autotracking;
• display of vectors of its extrapolated relative or true motion on the indicator screen;
• display of trajectories of the past movement of auto-tracked targets in the form of
dots;
• display of the form/logbook (bearing, range, course, speed, distance and time
of the shortest approach, distance and time of course crossing) of any selected
auto-tracked target;
• warning on target maneuver and on danger of collision;
• maneuver imitation with the heading and (or) speed of own ship to deviate from
an adjustable delay time of the maneuver beginning from 0 to 60 min.
The station provides the target detection stability when the ship rolls up to 10°,
which is ensured by the width of the antenna directional pattern in the vertical
plane. The station provides for a constantly switched on wobbling (chaotic change)
of sounding pulses repetition rate to protect against “false targets”-type interference caused by the phenomenon of radio wave overrefraction. The station has an
operatively switched on asynchronous interference filter that suppresses interference from neighboring radars of the 3-cm range. The station has electronic counter
countermeasures aids against reflections from the agitated sea surface and precipitation—operatively adjustable time corrected gain (TCG) and a short time constant
(differentiation).
Orientation and stabilization of radar image. Most modern shipboard radar
stations provide three modes of orientation of the radar image on the indicator screen:
heading (COURSE), stabilized heading (COURSE ST), or north (NORTH), and the
second and third modes are provided only when the station is coupled with the ship’s
heading indicator (gyrocompass, satellite compass, etc.).
In the absence of a heading indicator, the station operates only in the COURSE
mode. Examples of the radar image in the indicated modes are shown in Fig. 12.3.
The selection of the orientation mode NORTH, COURSE ST, or COURSE occurs
by pressing the COURSE NORTH COURSE ST button on the control panel, and the
selected mode is indicated on the panel MODES.
In COURSE orientation mode, the heading mark (OK) is always at the top at the
zero mark on the azimuth scale. At change of ship course (maneuver, yaw), the OK
position remains unchanged, while the blips from targets move in the direction on
the screen with each antenna rotation; i.e., the radar image is unstable in direction.
12 Radar Systems of Maritime Transport
The direction resolution probability of the station at 0.8 probability is not more
than 2.2°, and the limit of the permissible measuring error of directions is 0.8°.
Guard zone—the auto-lock-on zone for auto-tracking can be quickly switched
on and installed at an angle from 0.7 to 360°, in width up to 4 nautical miles, at a
distance of up to 24 nautical miles. The guard zone is effective if the boundaries of
the zone are observed on the screen within the included range scale. The sound signal
is given automatically when the target enters the zone and during its auto-lock-on
for auto-tracking (target acquisition).
The built-in automatic radar plotting system (ARPS) provides:
• automatic or manual lock-on/target acquisition of up to 30 targets for autotracking;
• display of vectors of its extrapolated relative or true motion on the indicator screen;
• display of trajectories of the past movement of auto-tracked targets in the form of
dots;
• display of the form/logbook (bearing, range, course, speed, distance and time
of the shortest approach, distance and time of course crossing) of any selected
auto-tracked target;
• warning on target maneuver and on danger of collision;
• maneuver imitation with the heading and (or) speed of own ship to deviate from
an adjustable delay time of the maneuver beginning from 0 to 60 min.
The station provides the target detection stability when the ship rolls up to 10°,
which is ensured by the width of the antenna directional pattern in the vertical
plane. The station provides for a constantly switched on wobbling (chaotic change)
of sounding pulses repetition rate to protect against “false targets”-type interference caused by the phenomenon of radio wave overrefraction. The station has an
operatively switched on asynchronous interference filter that suppresses interference from neighboring radars of the 3-cm range. The station has electronic counter
countermeasures aids against reflections from the agitated sea surface and precipitation—operatively adjustable time corrected gain (TCG) and a short time constant
(differentiation).
Orientation and stabilization of radar image. Most modern shipboard radar
stations provide three modes of orientation of the radar image on the indicator screen:
heading (COURSE), stabilized heading (COURSE ST), or north (NORTH), and the
second and third modes are provided only when the station is coupled with the ship’s
heading indicator (gyrocompass, satellite compass, etc.).
In the absence of a heading indicator, the station operates only in the COURSE
mode. Examples of the radar image in the indicated modes are shown in Fig. 12.3.
The selection of the orientation mode NORTH, COURSE ST, or COURSE occurs
by pressing the COURSE NORTH COURSE ST button on the control panel, and the
selected mode is indicated on the panel MODES.
In COURSE orientation mode, the heading mark (OK) is always at the top at the
zero mark on the azimuth scale. At change of ship course (maneuver, yaw), the OK
position remains unchanged, while the blips from targets move in the direction on
the screen with each antenna rotation; i.e., the radar image is unstable in direction.