5 Operational requirements for the radar system
The design and performance of the radar should be based on user requirements and up-to-date
navigational technology. It should provide effective target detection within the safety-relevant
environment surrounding own ship and should permit fast and easy situation evaluation.*
* Refer to MSC/Circ.878 - MEPC/Circ.346 on Interim Guidelines for the application of Human Element
Analysing Process (HEAP) to the IMO rule-making process. 5.01 Frequency
5.1.1 Frequency spectrum
The radar should transmit within the confines of the ITU allocated bands for maritime radar and
meet the requirements of the radio regulations and applicable ITU-R recommendations.
5.1.2 Radar Sensor Requirements
Radar systems of both X and S-Bands are covered in these performance standards:
- X-Band (9.2-9.5 GHz) for high discrimination, good sensitivity and tracking
performance; and
- S-Band (2.9-3.1 GHz) to ensure that target detection and tracking capabilities are
maintained in varying and adverse conditions of fog, rain and sea clutter.
The frequency band in use should be indicated.
5.1.3 Interference susceptibility
The radar should be capable of operating satisfactorily in typical interference conditions.
5.02 Radar Range and Bearing Accuracy
The radar system range and bearing accuracy requirements should be:
Range - within 30 m or 1% of the range scale in use, whichever is greater;
Bearing - within 1°.
5.03 Detection Performance and Anti-clutter Functions
All available means for the detection of targets should be used.
5.3.1 Detection
5.3.1.1 Detection in Clear Conditions
In the absence of clutter, for long range target and shoreline detection, the requirement for the
radar system is based on normal propagation conditions, in the absence of sea clutter,
precipitation and evaporation duct, with an antenna height of 15 m above sea level.
Based on:
- an indication of the target in at least 8 out of 10 scans or equivalent; and
- a probability of a radar detection false alarm of 10-4,
the requirement contained in Table 2 should be met as specified for X-Band and S-Band
equipment.
The detection performance should be achieved using the smallest antenna that is supplied with
the radar system.
Recognizing the high relative speeds possible between own ship and target, the equipment should
be specified and approved as being suitable for classes of ship having normal (30 kn) own ship speeds (100 kn and 140 kn relative speeds respectively).
TABLE 2
Minimum detection ranges in clutter-free conditions
______
1 IMO revised performance standards for radar reflectors (resolution MSC.164(78)) . Radar Cross Section
(RCS) 7.5 m2 for X-Band, 0.5 m2 for S-Band.
2 The corner reflector (used for measurement), is taken as 10 m2 for X-Band and 1.0 m2 for S-Band.
3 The typical navigation buoy is taken as 5.0 m2 for X-Band and 0.5 m2 for S-Band; for typical channel
markers, with an RCS of 1.0 m2 (X-band) and 0.1 m2 (S-band) and height of 1 metre, a detection range of
2.0 and 1.0 NM respectively.
4 RCS for 10 m small vessel taken as 2.5 m2 for X-Band and 1.4 m2 for S-Band (taken as a complex target).
5 Reflectors are taken as point targets, vessels as complex targets and shorelines as distributed targets (typical
values for a rocky shoreline, but are dependent on profile).
6Detection ranges experienced in practice will be affected by various factors, including atmospheric
conditions (e.g. evaporation duct), target speed and aspect, target material and target structure. These and
other factors may either enhance or degrade the detection ranges stated. At ranges between the first
detection and own ship, the radar return may be reduced or enhanced by signal multi-path, which depend on
factors such as antenna/target centroid height, target structure, sea state and radar frequency band.
5.3.1.2 Detection at Close Range
The short-range detection of the targets under the conditions specified in Table 2 should be
compatible with the requirement in paragraph 5.4.
5.3.1.3 Detection in Clutter Conditions
Performance limitations caused by typical precipitation and sea clutter conditions will result in a
reduction of target detection capabilities relative to those defined in 5.3.1.1 and Table 2.
5.3.1.3.1 The radar equipment should be designed to provide the optimum and most consistent
detection performance, restricted only by the physical limits of propagation.
5.3.1.3.2 The radar system should provide the means to enhance the visibility of targets in
adverse clutter conditions at close range.
5.3.1.3.3 Degradation of detection performance (related to the figures in Table 2) at various
ranges and target speeds under the following conditions, should be clearly stated in the user
manual:
- light rain (4 mm per hour) and heavy rain (16 mm per hour);
- sea state 2 and sea state 5; and
- and a combination of these.
5.3.1.3.4 The determination of performance in clutter and specifically, range of first detection, as
defined in the clutter environment in 5.3.1.3.3, should be tested and assessed against a
benchmark target, as specified in the Test Standard.
5.3.1.3.5 Degradation in performance due to a long transmission line, antenna height or any
other factors should be clearly stated in the user manual.
5.3.2 Gain and Anti-Clutter Functions
5.3.2.1 Means should be provided, as far as is possible, for the adequate reduction of unwanted
echoes, including sea clutter, rain and other forms of precipitation, clouds, sandstorms and
interference from other radars.
5.3.2.2 A gain control function should be provided to set the system gain or signal
threshold level.
5.3.2.3 Effective manual and automatic anti-clutter functions should be provided.
5.3.2.4 A combination of automatic and manual anti-clutter functions is permitted.
5.3.2.5 There should be a clear and permanent indication of the status and level for gain and all
anti-clutter control functions.
5.3.3 Signal Processing
5.3.3.1 Means should be available to enhance target presentation on the display.
5.3.3.2 The effective picture update period should be adequate, with minimum latency to ensure
that the target detection requirements are met.
5.3.3.3 The picture should be updated in a smooth and continuous manner.
5.3.3.4 The equipment manual should explain the basic concept, features and limitations of any
signal processing.
5.3.4 Operation with SARTs and Radar Beacons
5.3.4.1 The X-Band radar system should be capable of detecting radar beacons in the relevant
frequency band.
5.3.4.2 The X-Band radar system should be capable of detecting SARTs and radar target
enhancers.
5.3.4.3 It should be possible to switch off those signal processing functions, including
polarization modes, which might prevent an X-Band radar beacon or SARTs from being detected
and displayed. The status should be indicated.
5.04 Minimum Range
5.4.1 With own ship at zero speed, an antenna height of 15 m above the sea level and in calm
conditions, the navigational buoy in Table 2 should be detected at a minimum horizontal range of
40 m from the antenna position and up to a range of 1 NM, without changing the setting of
control functions other than the range scale selector.
5.4.2 Compensation for any range error should be automatically applied for each selected
antenna, where multiple antennas are installed.
5.05 Discrimination
Range and bearing discrimination should be measured in calm conditions, on a range scale of
1.5 NM or less and at between 50% and 100% of the range scale selected:
5.5.1 Range
The radar system should be capable of displaying two point targets on the same bearing,
separated by 40 m in range, as two distinct objects.
5.5.2 Bearing
The radar system should be capable of displaying two point targets at the same range, separated
by 2.5° in bearing, as two distinct objects.
5.06 Roll and Pitch
The target detection performance of the equipment should not be substantially impaired when
own ship is rolling or pitching up to +/-10°.
5.07 Radar Performance Optimization and Tuning
5.7.1 Means should be available to ensure that the radar system is operating at the best
performance. Where applicable to the radar technology, manual tuning should be provided and
additionally, automatic tuning may be provided.
5.7.2 An indication should be provided, in the absence of targets, to ensure that the system is
operating at the optimum performance.
5.7.3 Means should be available (automatically or by manual operation) and while the
equipment is operational, to determine a significant drop in system performance relative to a
calibrated standard established at the time of installation.
5.08 Radar Availability
The radar equipment should be fully operational (RUN status) within 4 minutes after switch ON
from cold. A STANDBY condition should be provided, in which there is no operational radar
transmission. The radar should be fully operational within 5 sec from the standby condition.
5.09 Radar Measurements - Consistent Common Reference Point (CCRP)
5.9.1 Measurements from own ship (e.g. range rings, target range and bearing, cursor, tracking
data) should be made with respect to the consistent common reference point (e.g. conning
position). Facilities should be provided to compensate for the offset between antenna position
and the consistent common reference point on installation. Where multiple antennas are
installed, there should be provision for applying different position offsets for each antenna in the
radar system. The offsets should be applied automatically when any radar sensor is selected.
5.9.2 Own ship.s scaled outline should be available on appropriate range scales. The consistent
common reference point and the position of the selected radar antenna should be indicated on this
graphic.
5.9.3 When the picture is centred, the position of the Consistent Common Reference Point
should be at the centre of the bearing scale. The off-centre limits should apply to the position of
the selected antenna.
5.9.4 Range measurements should be in nautical miles (NM). In addition, facilities for metric
measurements may be provided on lower range scales. All indicated values for range
measurement should be unambiguous.
5.9.5 Radar targets should be displayed on a linear range scale and without a range index delay.
5.10 Display Range Scales
5.10.1 Range scales of 0.25, 0.5, 0.75, 1.5, 3, 6, 12 and 24 NM should be provided. Additional
range scales are permitted outside the mandatory set. Low metric range scales may be offered in
addition to the mandatory set.
5.10.2 The range scale selected should be permanently indicated.
5.12 Variable Range Markers (VRM)
5.12.1 At least two variable range markers (VRMs) should be provided. Each active VRM
should have a numerical readout and have a resolution compatible with the range scale in use.
5.12.2 The VRMs should enable the user to measure the range of an object within the
operational display area with a maximum system error of 1% of the range scale in use or 30 m,
whichever is the greater distance.
5.13 Bearing Scale
5.13.1 A bearing scale around the periphery of the operational display area should be provided.
The bearing scale should indicate the bearing as seen from the consistent common reference
point.
5.13.2 The bearing scale should be outside of the operational display area. It should be
numbered at least every 30° division and have division marks of at least 5°. The 5° and
10° division marks should be clearly distinguishable from each other. 1° division marks may be
presented where they are clearly distinguishable from each other.
5.14 Heading Line (HL)
5.14.1 A graphic line from the consistent common reference point to the bearing scale should
indicate the heading of the ship.
5.14.2 Electronic means should be provided to align the heading line to within 0.1°. If there is
more than one radar antenna (see 5.35) the heading skew (bearing offset) should be retained and
automatically applied when each radar antenna is selected.
5.14.3 Provision should be made to temporarily suppress the heading line. This function may be
combined with the suppression of other graphics.
5.15 Electronic Bearing Lines (EBLs)
5.15.1 At least two electronic bearing lines (EBLs) should be provided to measure the bearing of
any point object within the operational display area, with a maximum system error of 1° at the
periphery of the display.
5.15.2 The EBLs should be capable of measurement relative to the ships heading and relative to
true north. There should be a clear indication of the bearing reference (i.e. true or relative).
5.15.3 It should be possible to move the EBL origin from the consistent common reference point
to any point within the operational display area and to reset the EBL to the consistent common
reference point by a fast and simple action.
5.15.4 It should be possible to fix the EBL origin or to move the EBL origin at the velocity of
own ship.
5.15.5 Means should be provided to ensure that the user is able to position the EBL smoothly in
either direction, with an incremental adjustment adequate to maintain the system measurement
accuracy requirements.
5.15.6 Each active EBL should have a numerical readout with a resolution adequate to maintain
the system measurement accuracy requirements.
5.16 Parallel Index lines (PI)
5.16.1 A minimum of four independent parallel index lines, with a means to truncate and switch
off individual lines, should be provided.
5.16.2 Simple and quick means of setting the bearing and beam range of a parallel index line
should be provided. The bearing and beam range of any selected index line should be available
on demand.
5.17 Offset Measurement of Range and Bearing
There should be a means to measure the range and bearing of one position on the display relative
to any other position within the operational display area.
5.18 User Cursor
5.18.1 A user cursor should be provided to enable a fast and concise means to designate any
position on the operational display area.
5.18.2 The cursor position should have a continuous readout to provide the range and bearing,
measured from the consistent common reference point, and/or the latitude and longitude of the
cursor position presented either alternatively or simultaneously.
5.18.3 The cursor should provide the means to select and de-select targets, graphics or objects
within the operational display area. In addition, the cursor may be used to select modes,
functions, vary parameters and control menus outside of the operational display area.
5.18.4 Means should be provided to easily locate the cursor position on the display.
5.18.5 The accuracy of the range and bearing measurements provided by the cursor should meet
the relevant requirements for VRM and EBL.
5.19 Azimuth Stabilization
5.19.1 The heading information should be provided by a gyrocompass or by an equivalent sensor
with a performance not inferior to the relevant standards adopted by the Organization.
5.19.2 Excluding the limitations of the stabilizing sensor and type of transmission system, the
accuracy of azimuth alignment of the radar presentation should be within 0.5° with a rate of turn
likely to be experienced with the class of ship.
5.19.3 The heading information should be displayed with a numerical resolution to permit
accurate alignment with the ship gyro system.
5.19.4 The heading information should be referenced to the consistent common reference point
(CCRP).
5.20 Display Mode of the Radar Picture
5.20.1 A True Motion display mode should be provided. The automatic reset of own ship may
be initiated by its position on the display, or time related, or both. Where the reset is selected to
occur at least on every scan or equivalent, this should be equivalent to True Motion with a fixed
origin (in practice equivalent to the previous relative motion mode).
5.20.2 North Up and Course Up orientation modes should be provided. Head Up may be
provided when the display mode is equivalent to True Motion with a fixed origin (in practice
equivalent to the previous relative motion Head Up mode).
5.21 Off-Centring
5.21.1 Manual off-centring should be provided to locate the selected antenna position at any
point within at least 50% of the radius from the centre of the operational display area.
5.21.2 On selection of off-centred display, the selected antenna position should be capable of
being located to any point on the display up to at least 50%, and not more than 75%, of the radius
from the centre of the operational display area. A facility for automatically positioning own ship
for the maximum view ahead may be provided.
5.21.3 In True Motion, the selected antenna position should automatically reset up to a
50% radius to a location giving the maximum view along own ship.s course. Provision for an
early reset of selected antenna position should be provided.
5.22 Ground and Sea Stabilization Modes
5.22.1 Ground and Sea stabilization modes should be provided.
5.22.2 The stabilization mode and stabilization source should be clearly indicated.
5.22.3 The source of own ships’ speed should be indicated and provided by a sensor approved in
accordance with the requirements of the Organization for the relevant stabilization mode.
5.23 Target Trails and Past Positions
5.23.1 Variable length (time) target trails should be provided, with an indication of trail time and
mode. It should be possible to select true or relative trails from a reset condition for all true
motion display modes.
5.23.2 The trails should be distinguishable from targets.
5.23.3 Either scaled trails or past positions or both, should be maintained and should be available
for presentation within 2 scans or equivalent, following:
- the reduction or increase of one range scale;
- the offset and reset of the radar picture position; and
- a change between true and relative trails.
5.24 Presentation of Target Information
5.24.1 Targets should be presented in accordance with the performance standards for the
Presentation of Navigation-related Information on Shipborne Navigational Displays adopted by
the Organization and with their relevant symbols according to SN/Circ.243.
5.24.2 The target information may be provided by the radar target tracking function and by the
reported target information from the Automatic Identification System (AIS).
5.24.3 The operation of the radar tracking function and the processing of reported
AIS information is defined in these standards.
5.24.4 The number of targets presented, related to display size, is defined in Table 1.
An indication should be given when the target capacity of radar tracking or AIS reported target
processing/display capability is about to be exceeded.
5.24.5 As far as practical, the user interface and data format for operating, displaying and
indicating AIS and radar tracking information should be consistent.
5.25 Target Tracking (TT) and Acquisition
5.25.1 General
Radar targets are provided by the radar sensor (transceiver). The signals may be filtered
(reduced) with the aid of the associated clutter controls. Radar targets may be manually or
automatically acquired and tracked using an automatic Target Tracking (TT) facility.
5.25.1.1 The automatic target tracking calculations should be based on the measurement of radar
target relative position and own ship motion.
5.25.1.2 Any other sources of information, when available, may be used to support the optimum
tracking performance.
5.25.1.3 TT facilities should be available on at least the 3, 6, and 12 NM range scales. Tracking
range should extend to a minimum of 12 NM.
5.25.1.4 The radar system should be capable of tracking targets having the maximum relative
speed relevant to its classification for normal or high own ship speeds (see 5.3).
5.25.2 Tracked Target Capacity
5.25.2.1 In addition to the requirements for processing of targets reported by AIS, it should be
possible to track and provide full presentation functionality for a minimum number of tracked
radar targets according to Table 1.
5.25.2.2 There should be an indication when the target tracking capacity is about to be exceeded.
Target overflow should not degrade the radar system performance.
5.25.3 Acquisition
5.25.3.1 Manual acquisition of radar targets should be provided with provision for acquiring at
least the number of targets specified in Table 1.
5.25.3.2 Automatic acquisition should be provided where specified in Table 1. In this case,
there should be means for the user to define the boundaries of the auto-acquisition area.
5.25.4 Tracking
5.25.4.1 When a target is acquired, the system should present the trend of the target’s motion
within one minute and the prediction of the targets’ motion within 3 minutes.
5.25.4.2 TT should be capable of tracking and updating the information of all acquired targets
automatically.
5.25.4.3 The system should continue to track radar targets that are clearly distinguishable on the
display for 5 out of 10 consecutive scans or equivalent.
5.25.4.4 The TT design should be such that target vector and data smoothing is effective, while
target manoeuvres should be detected as early as possible.
5.25.4.5 The possibility of tracking errors, including target swap, should be minimized by
design.
5.25.4.6 Separate facilities for cancelling the tracking of any one and of all target(s) should be
provided.
5.25.4.7 Automatic tracking accuracy should be achieved when the tracked target has achieved a
steady state, assuming the sensor errors allowed by the relevant performance standards of the
Organization.
5.25.4.7.1 For ships capable of up to 30 kn true speed, the tracking facility should present,
within 1 min steady state tracking, the relative motion trend and after 3 minutes, the predicted
motion of a target, within the following accuracy values (95% probability):
TABLE 3
Tracked Target Accuracy (95% probability figures)
Accuracy may be significantly reduced during or shortly after acquisition, own ship manoeuvre,
a manoeuvre of the target, or any tracking disturbance and is also dependent on own ship.s
motion and sensor accuracy.
Measured target range and bearing should be within 50 m (or +/-1% of target range) and 2°.
The testing standard should have detailed target simulation tests as a means to confirm the
accuracy of targets with relative speeds of up to 100 kn. Individual accuracy values shown in the
table above may be adapted to account for the relative aspects of target motion with respect to
that of own ship in the testing scenarios used.
5.25.4.7.2 For ships capable of speeds in excess of 30 kn (typically High-Speed Craft (HSC))
and with speeds of up to 70 kn, there should be additional steady state measurements made to
ensure that the motion accuracy, after 3 minutes of steady state tracking, is maintained with
target relative speeds of up to 140 kn.
5.25.4.8 A ground referencing function, based on a stationary tracked target, should be provided.
Targets used for this function should be marked with the relevant symbol defined in SN/Circ.
5.26 Automatic Identification System (AIS) Reported Targets
5.26.1 General
Reported targets provided by the AIS may be filtered according to user-defined parameters.
Targets may be sleeping, or may be activated. Activated targets are treated in a similar way to
radar tracked targets.
5.26.2 AIS Target Capacity
In addition to the requirements for radar tracking, it should be possible to display and provide full
presentation functionality for a minimum number of sleeping and activated AIS targets according
to Table 1. There should be an indication when the capacity of processing/display of AIS targets
is about to be exceeded.
5.26.3 Filtering of AIS Sleeping Targets
To reduce display clutter, a means to filter the presentation of sleeping AIS targets should be
provided, together with an indication of the filter status. (e.g. by target range, CPA/TCPA or
AIS target class A/B, etc.). It should not be possible to remove individual AIS targets from the
display.
5.26.4 Activation of AIS Targets
A means to activate a sleeping AIS target and to deactivate an activated AIS target should be
provided. If zones for the automatic activation of AIS targets are provided, they should be the
same as for automatic radar target acquisition. In addition, sleeping AIS targets may be
automatically activated when meeting user defined parameters (e.g. target range, CPA/TCPA or
AIS target class A/B).
5.26.5 AIS Presentation Status
TABLE 4
The AIS presentation status should be indicated as follows:
5.27 AIS Graphical Presentation
Targets should be presented with their relevant symbols according to the performance standards
for the Presentation of Navigation-related Information on Shipborne Navigational Displays
adopted by the Organization and SN/Circ.243.
5.27.1 AIS targets that are displayed should be presented as sleeping targets by default.
5.27.2 The course and speed of a tracked radar target or reported AIS target should be indicated
by a predicted motion vector. The vector time should be adjustable and valid for presentation of
any target regardless of its source.
5.27.3 A permanent indication of vector mode, time and stabilization should be provided.
5.27.4 The consistent common reference point should be used for the alignment of tracked radar
and AIS symbols with other information on the same display.
5.27.5 On large scale/low range displays, a means to present the true scale outline of an activated
AIS target should be provided. It should be possible to display the past track of activated targets.
5.28 AIS and Radar Target Data
5.28.1 It should be possible to select any tracked radar or AIS target for the alphanumeric
display of its data. A target selected for the display of its alphanumeric information should be
identified by the relevant symbol. If more than one target is selected for data display, the
relevant symbols and the corresponding data should be clearly identified. There should be a clear
indication to show that the target data is derived from radar or from AIS.
5.28.2 For each selected tracked radar target, the following data should be presented in
alphanumeric form: source(s) of data, actual range of target, actual bearing of target, predicted
target range at the closest point of approach (CPA), predicted time to CPA (TCPA), true course
of target, true speed of target.
5.28.3 For each selected AIS target the following data should be presented in alphanumeric
form: Source of data, ship.s identification, navigational status, position where available and its
quality, range, bearing, COG, SOG, CPA and TCPA. Target heading and reported rate of turn
should also be made available. Additional target information should be provided on request.
5.28.4 If the received AIS information is incomplete, the absent information should be clearly
indicated as .missing. within the target data field.
5.28.5 The data should be displayed and continually updated, until another target is selected for
data display or until the window is closed.
5.28.6 Means should be provided to present own ship AIS data on request.
5.29 Operational Alarms
A clear indication of the cause for all alarm criteria should be given.
5.29.1 If the calculated CPA and TCPA values of a tracked target or activated AIS target are less
than the set limits:
• A CPA/TCPA alarm should be given.
• The target should be clearly indicated.
5.29.2 The preset CPA/TCPA limits applied to targets from radar and AIS should be identical.
As a default state, the CPA/TCPA alarm functionality should be applied to all activated
AIS targets. On user request the CPA/TCPA alarm functionality may also be applied to sleeping
targets.
5.29.3 If a user defined acquisition/activation zone facility is provided, a target not previously
acquired/activated entering the zone, or is detected within the zone, should be clearly identified
with the relevant symbol and an alarm should be given. It should be possible for the user to set
ranges and outlines for the zone.
5.29.4 The system should alert the user if a tracked radar target is lost, rather than excluded by a
pre-determined range or pre-set parameter. The target.s last position should be clearly indicated
on the display.
5.29.5 It should be possible to enable or disable the lost target alarm function for AIS targets.
A clear indication should be given if the lost target alarm is disabled.
If the following conditions are met for a lost AIS target:
• The AIS lost target alarm function is enabled.
• The target is of interest, according to lost target filter criteria.
• A message is not received for a set time, depending on the nominal reporting rate
of the AIS target.
Then:
• The last known position should be clearly indicated as a lost target and an alarm
be given.
• The indication of the lost target should disappear if the signal is received again, or
after the alarm has been acknowledged.
• A means of recovering limited historical data from previous reports should be
provided.
5.30 AIS and Radar Target Association
An automatic target association function based on harmonized criteria avoids the presentation of
two target symbols for the same physical target.
5.30.1 If the target data from AIS and radar tracking are both available and if the association
criteria (e.g. position, motion) are fulfilled such that the AIS and radar information are
considered as one physical target, then as a default condition, the activated AIS target symbol
and the alphanumeric AIS target data should be automatically selected and displayed.
5.30.2 The user should have the option to change the default condition to the display of tracked
radar targets and should be permitted to select either radar tracking or AIS alphanumeric data.
5.30.3 For an associated target, if the AIS and radar information become sufficiently different,
the AIS and radar information should be considered as two distinct targets and one activated AIS
target and one tracked radar target should be displayed. No alarm should be raised.
5.31 Trial Manoeuvre
The system should, where required by table 1, be capable of simulating the predicted effects of
own ships manoeuvre in a potential threat situation and should include own ship.s dynamic
characteristics. A trial manoeuvre simulation should be clearly identified. The requirements are:
• The simulation of own ship course and speed should be variable.
• A simulated time to manoeuvre with a countdown should be provided.
• During simulation, target tracking should continue and the actual target data
should be indicated.
• Trial manoeuvre should be applied to all tracked targets and at least all activated
AIS targets.
5.32 The Display of Maps, Navigation Lines and Routes
5.32.1 It should be possible for the user to manually create and change, save, load and display
simple maps/navigation lines/routes referenced to own ship or a geographical position. It should
be possible to remove the display of this data by a simple operator action.
5.32.2 The maps/navigation lines/routes may consist of lines, symbols and reference points.
5.32.3 The appearance of lines, colours and symbols are as defined in SN/Circ.243.
5.32.4 The maps/navigation lines/route graphics should not significantly degrade the radar
information.
5.32.5 The maps/navigation lines/routes should be retained when the equipment is
switched OFF.
5.32.6 The maps/navigation lines/route data should be transferable whenever a relevant
equipment module is replaced.
5.33 The Display of Charts
5.33.1 The radar system may provide the means to display ENC and other vector chart
information within the operational display area to provide continuous and real-time position
monitoring. It should be possible to remove the display of chart data by a single operator action.
5.33.2 The ENC information should be the primary source of information and should comply
with IHO relevant standards. Status of other information should be identified with a permanent
indication. Source and update information should be made available.
5.33.3 As a minimum, the elements of the ECDIS Standard Display should be made available
for individual selection by category or layer, but not as individual objects.
5.33.4 The chart information should use the same reference and co-ordinate criteria as the
radar/AIS, including datum, scale, orientation, CCRP and stabilization mode.
5.33.5 The display of radar information should have priority. Chart information should be
displayed such that radar information is not substantially masked, obscured or degraded. Chart
information should be clearly perceptible as such.
5.33.6 A malfunction of the source of chart data should not affect the operation of the radar/AIS
system.
5.33.7 Symbols and colours should comply with the performance standards for the Presentation
of Navigation-related Information on Shipborne Navigational Displays adopted by the
Organization (SN/Circ.243).
5.34 Alarms and Indications
Alarms and indications should comply with the performance standards for the Presentation of
Navigation-related Information on Shipborne Navigational Displays adopted by the
Organization.
5.34.1 A means should be provided to alert the user of .picture freeze..
5.34.2 Failure of any signal or sensor in use, including; gyro, log, azimuth, video, sync and
heading marker, should be alarmed. System functionality should be limited to a fall back mode
or in some cases, the display presentation should be inhibited (see fallback modes, section 9).
5.35 Integrating Multiple Radars
5.35.1 The system should safeguard against single point system failure. Fail-safe condition
should be applied in the event of an integration failure.
5.35.2 The source and any processing or combination of radar signals should be indicated.
5.35.3 The system status for each display position should be available.
6 Ergonomic criteria
6.1 Operational Controls
6.1.1 The design should ensure that the radar system is simple to operate. Operational controls
should have a harmonized user interface and be easy to identify and simple to use.
6.1.2 The radar system should be capable of being switched ON or OFF at the main system
radar display or at a control position.
6.1.3 The control functions may be dedicated hardware, screen accessed or a combination of
these; however the primary control functions should be dedicated hardware controls or soft keys,
with an associated status indication in a consistent and intuitive position.
6.1.4 The following are defined as primary radar control functions and should be easily and
immediately accessible:
Radar Standby/RUN, Range scale selection, Gain, tuning function (if applicable), Anti-clutter
rain, Anti-clutter sea, AIS function on/off, Alarm acknowledge, Cursor, a means to set
EBL/VRM, display brightness and acquisition of radar targets.
6.1.5 The primary functions may also be operated from a remote operating position in addition
to the main controls.
6.2 Display Presentation
6.2.1 The display presentation should comply with the performance standards for the
Presentation of Navigation-related Information on Shipborne Navigational Displays adopted by
the Organization.
6.2.2 The colours, symbols and graphics presented should comply with SN/Circ. 243.
6.2.3 The display sizes should conform to those defined in Table 1.
6.3 Instructions and Documentation
6.3.1 Documentation Language
The operating instructions and manufacturer.s documentation should be written in a clear and
comprehensible manner and should be available at least in the English language.
6.3.2 Operating Instructions
The operating instructions should contain a qualified explanation and/or description of
information required by the user to operate the radar system correctly, including:
- appropriate settings for different weather conditions;
- monitoring the radar system.s performance;
- operating in a failure or fall-back situation;
- limitations of the display and tracking process and accuracy, including any delays;
- using heading and SOG/COG information for collision avoidance;
- limitations and conditions of target association;
- criteria of selection for automatic activation and cancellation of targets;
- methods applied to display AIS targets and any limitations;
- principles underlying the trial manoeuvre technology, including simulation of own
ship.s manoeuvring characteristics, if provided;
- alarms and indications;
- installation requirements as listed under section 7.5;
- radar range and bearing accuracies; and
- any special operation (e.g. tuning) for the detection of SARTs; and
- the role of the CCRP for radar measurements and its specific value.
6.3.3 Manufacturer.s Documentation
6.3.3.1 The manufacturer.s documentation should contain a description of the radar system and
factors that may affect detection performance, including any latency in signal processing.
6.3.3.2 Documentation should describe the basis of AIS filter criteria and AIS/radar target
association criteria.
6.3.3.3 The equipment documentation should include full details of installation information,
including additional recommendations on unit location and factors that may degrade performance
or reliability.
Appendix 2 Definitions
Activated AIS target
A target representing the automatic or manual activation of
a sleeping target for the display of additional graphically
presented information. The target is displayed by an
- activated target. symbol including:
- a vector (COG / SOG);
- the heading; and
- ROT or direction of turn indication (if available) to
indicate initiated course changes.
Acquisition of a radar target
Process of acquiring a target and initiating its tracking.
Activation of an AIS target
Activation of a sleeping AIS target for the display of
additional graphical and alphanumerical information.
Acquired radar target
Automatic or manual acquisition initiates radar tracking.
Vectors and past positions are displayed when data has
achieved a steady state condition.
AIS
Automatic Identification System./DD>
AIS target
A target generated from an AIS message. See activated
target, lost target, selected target and sleeping target.
Associated target
If an acquired radar target and an AIS reported target have
similar parameters (e.g. position, course, speed) complying
with an association algorithm, they are considered to be the
same target and become an associated target.
Acquisition/activation zone
A zone set up by the operator in which the system should
automatically acquire radar targets and activate reported
AIS targets when entering the zone.
CCRP
Consistent Common Reference Point: A location on
own ship, to which all horizontal measurements such as
target range, bearing, relative course, relative speed, closest
point of approach (CPA) or time to closest point of
approach (TCPA) are referenced, typically the conning
position of the bridge.
CPA/TCPA
Closest Point of Approach / Time to the Closest Point of Approach: Distance to the closest point of approach (CPA) and time to the closest point of approach (TCPA). Limits are set by the operator related to own ship.
Course Over Ground (COG)
Direction of the ship’s movement relative to the earth,
measured on board the ship, expressed in angular units from
true north.
Course Through Water (CTW)
Direction of the ship’s movement through the water, defined
by the angle between the meridian through its position and
the direction of the ship’s movement through the water,
expressed in angular units from true north.
Dangerous target
A target whose predicted CPA and TCPA are violating the
values as preset by the operator. The respective target is
marked by a .dangerous target. symbol.
Display modes
Relative motion: means a display on which the position of
own ship remains fixed, and all targets move relative to
own ship.
True motion: a display across which own ship moves with
its own true motion.
Display orientation
North up display: an azimuth stabilized presentation
which uses the gyro input (or equivalent) and north is
uppermost on the presentation.
Course up display: an azimuth stabilized presentation
which uses the gyro input or equivalent and the ship.s
course is uppermost on the presentation at the time of
selection.
Head up display: an unstabilized presentation in which
own ship.s heading is uppermost on the presentation.
ECDIS
Electronic Chart Display and Information System.
ECDIS
Display Base The level of information which cannot be removed from the
ECDIS display, consisting of information which is required
at all times in all geographic areas and all circumstances. It
is not intended to be sufficient for safe navigation.
ECDIS
Standard Display The level of information that should be shown when a chart
is first displayed on ECDIS. The level of the information it
provides for route planning or route monitoring may be
modified by the mariner according to the mariner’s needs.
ENC
Electronic Navigational Chart. The database standardized
as to content, structure and format according to relevant
IHO standards and issued by, or on the authority of, a
Government.
EPFS
Electronic Position Fixing System.
ERBL
Electronic bearing line carrying a marker, which is
combined with the range marker, used to measure range and
bearing from own ship or between two objects.
Evaporation duct
A low lying duct (a change in air density) that traps the
radar energy so that it propagates close to the sea surface.
Ducting may enhance or reduce radar target detection
ranges.
Heading
Direction in which the bow of a ship is pointing expressed
as an angular displacement from north.
HSC
High-speed craft (HSC) are vessels which comply with the
definition in SOLAS for high speed craft.
Latency
The delay between actual and presented data.
Lost AIS target
A target representing the last valid position of an AIS target
before the reception of its data was lost. The target is
displayed by a .lost AIS target. symbol.
Lost tracked target
Target information is no longer available due to poor, lost
or obscured signals. The target is displayed by a .lost
tracked radar target. symbol.
Maps/Nav lines
Operator defined or created lines to indicate channels, Traffic Separation Schemes or borders of any area important for navigation.
Operational display area
Area of the display used to graphically present chart and
radar information, excluding the user dialogue area. On the
chart display this is the area of the chart presentation. On
the radar display this is the area encompassing the radar
image.
Past positions
Equally time-spaced past position marks of a tracked or
reported target and own ship. The past positions. track may
be either relative or true.
Radar
(Radio direction and ranging). A radio system that allows the determination of distance and direction of reflecting
objects and of transmitting devices.
Radar beacon
A navigation aid which responds to the radar transmission
by generating a radar signal to identify its position and
identity.
Radar detection false alarm
The probability of a radar false alarm represents the
probability that noise will cross the detection threshold and
be called a target when only noise is present.
Radar target
Any object fixed or moving whose position and motion is
determined by successive radar measurements of range and
bearing.
Radar target enhancer
An electronic radar reflector, the output of which is an
amplified version of the received radar pulse without any
form of processing except limiting.
Reference target
Symbol indicating that the associated tracked stationary
target (e.g. a navigational mark) is used as a speed reference
for the ground stabilization.
Relative bearing
Direction of a target.s position from own ship.s reference
location expressed as an angular displacement from own
ship's heading.
Relative course
Direction of motion of a target relative to own ship.s
direction. (Bearing).
Relative motion
Combination of relative course and relative speed.
Relative speed
Speed of a target relative to own ship.s speed data.
Rate of turn
Change of heading per time unit.
SART
Search And Rescue Transponder.
SDME
Speed and Distance Measuring Equipment.
Selected target
A manually selected target for the display of detailed
alphanumeric information in a separate data display area.
The target is displayed by a .selected target. symbol.
Sleeping AIS target
A target indicating the presence and orientation of a vessel
equipped with AIS in a certain location. The target is
displayed by a .sleeping target. symbol. No additional
information is presented until activated.
Stabilization modes
Ground stabilization: Display mode in which speed and
course information are referred to the ground, using ground
track input data, or EPFS as reference.
Sea stabilization: Display mode in which speed and
course information are referred to the sea, using gyro or
equivalent and water speed log input as reference.
Standard display
The level of information that should be shown when a chart
is first displayed on ECDIS. The level of the information it
provides for route planning or route monitoring may be
modified by the mariner according to the mariner’s needs.
Standard radar reflector
Reference reflector mounted 3.5 m above sea level with
10 m2 effective reflecting area at X-Band.
Steady state tracking
Tracking a target, proceeding at steady motion:
- after completion of the acquisition process, or
- without a manoeuvre of target or own ship, or
- without target swap or any disturbance.
Speed Over Ground (SOG)
Speed of the ship relative to the earth, measured on board of
the ship.
Speed Through Water
Speed of the ship relative to the water surface.
SOLAS
International Convention for the Safety of Life at Sea.
Suppressed area
An area set up by the operator within which targets are not
acquired.
Target swap
Situation in which the incoming radar data for a tracked
target becomes incorrectly associated with another tracked
target or a non-tracked radar echo.
Target's predicted motion
Prediction of a target.s future course and speed based on
linear extrapolation from its present motion as determined
by past measurements of its range and bearing on the radar.
Target Tracking (TT)
Computer process of observing the sequential changes in
the position of a radar target in order to establish its motion.
Such a target is a Tracked Target.
Trails
Tracks displayed by the radar echoes of targets in the form
of an afterglow. Trails may be true or relative.
Trial manoeuvre
Graphical simulation facility used to assist the operator to
perform a proposed manoeuvre for navigation and collision
avoidance purposes, by displaying the predicted future
status of at least all acquired or activated targets as a result
of own ship.s simulated manoeuvres.
True bearing
Direction of a target from own ship.s reference location or
from another target.s position expressed as an angular
displacement from true north.
True course
Direction of motion relative to ground or to sea, of a target
expressed as an angular displacement from north.
True motion
Combination of true course and true speed.
True speed
Speed of a target relative to ground, or to sea.
Vector modes
True vector: Vector representing the predicted true motion
of a target, showing course and speed with reference to the
ground.
Relative vector: Predicted movement of a target relative to
own ship.s motion.
User configured presentation
A display presentation configured by the user for a specific
task at hand. The presentation may include radar and/or
chart information, in combination with other navigation or
ship related data.
User dialogue area
Is an area of the display consisting of data fields and/or
menus that is allocated to the interactive presentation and
entry or selection of operational parameters, data and
commands mainly in alphanumeric form.