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Statutory Documents - IMO Publications and Documents - Resolutions - Assembly - IMO Resolution A.820(19) Performance Standards for Navigational Radar Equipment for High Speed Craft (adopted on 23 November 1995) - Annex - Performance Standards for Navigational Radar Equipment for High Speed Craft

Annex - Performance Standards for Navigational Radar Equipment for High Speed Craft

  1 Introduction

  1.1 The radar equipment is intended for installation in high speed craft (HSC) with the following characteristics:

  • .1 a maximum speed of 70 knots;

  • .2 a maximum rate of turn 20/s; and

  • .3 normally operate between latitudes 70N and 70S.

  1.2 In addition to the general requirements contained in Resolution A.694(17), the radar equipment should comply with the following minimum performance requirements.

  2 General

 The radar equipment should provide an indication, in relation to the craft, of the position of other surface craft and obstructions and of buoys, shorelines and navigational marks in a manner which will assist in navigation and in avoiding collision.

  3 Range Performance

 The operational requirement, where the radar antenna is mounted 7.5 m above sea level, is that the equipment should give a clear indication of surface objects such as a navigational buoy having an effective echoing area of approximately 10 m2 at 2.5 nautical miles in the absence of clutter.

  4 Minimum Range

 The surface objects specified in 3 should be clearly displayed form a minimum range of 35 m up to a range of one nautical mile, without changing the setting of controls other than the range selector.

  5 Display

  5.1 The equipment should, without external magnification, provide a multi-colour daylight display with an effective radar picture diameter of not less than 250 mm.

  5.2 Day and night colours should be provided; it should be possible to adjust brightness.

  5.3 The equipment should provide the following set of range scales of display:

0.25, 0.5, 0.75, 1.5, 3, 6, 12 and 24 nautical miles

  5.4 Additional range scales may be provided.

  5.5 The range scales displayed and, when in use, the distance between range rings should be clearly indicated.

  5.6 Off-centre facilities should be provided of at least a minimum of 50% and not more than 75% of range scale in use.

  6 Range Measurement

  6.1 Fixed electronic range rings should be provided for range measurements as follows

  • .1 on the range scales of 0.25, 0.5 and 0.75 nautical miles at least two range rings; and

  • .2 on all other range scales six range rings should be provided.

  6.2 A variable electronic range marker should be provided with a numeric readout of range.

  6.3 The fixed range rings and the variable range marker should enable the range of an object to be measured with an error not exceeding 1% of the maximum range of the scale in use, or 30 m, whichever is the greater.

  6.4 It should be possible to vary the brilliance of the fixed range rings and the variable marker and to remove them completely from the display.

  7 Heading Indicator

  7.1 The heading of the craft should be indicated by a line on the display with a maximum error not greater than 1. The thickness of the display heading should not be greater than 0.5 measured at maximum range at the edge of the screen.

  7.2 Provision should be made to switch off the heading indicator by a device which cannot be left in the heading marker off position.

  8 Bearing Measurement

  8.1 Provision should be made to obtain quickly the bearing of any object whose echo appears on the display.

  8.2 The means provided for obtaining bearing should enable the bearing of a target whose echo appears at the edge of the display to be measured with an accuracy of 1 or better.

  8.3 A minimum of two lines for parallel indexing should be available

  9 Discrimination

  9.1 The equipment should be capable of displaying as separate indications on a range scale of 1 nautical mile or less, two 10 m2targets in the absence of sea clutter at a range of between 50% and 100% of the range scale in use, and on the same azimuth, separated by not more than 35 m in range.

  9.2 The equipment should be capable of displaying as separate indications two (10 m2) targets both situated at the same range between 50% and 100% of 1 mile range, on the 1.5 mile range scale and separated by not more than 2.5 for X band radars and 4 for S band radars.

  10 Roll or Pitch

 The performance of the equipment should be such that when the craft is rolling and pitching up to 10 the range performance requirements of 3 and 4 continue to be met.

  11 Scan

 The scan should be clockwise, continuous and automatic through 360 of azimuth. The scan rate should not be less than 40 revolutions per minute. The equipment should operate satisfactorily in relative wind speeds of up to 100 knots.

  12 Azimuth Stabilization

  12.1 Means should be provided to enable the display to be stabilized in azimuth by an approved directional sensor. The equipment should be provided with an approved directional sensor input to enable it to be stabilized in azimuth. The accuracy of alignment with the approved directional sensor transmission should be within 0.5 with a rate of turn of 20/s.

  12.2 The equipment should operate satisfactorily in the unstabilized mode when the main approved directional sensor is inoperative.

  13 Performance Check

 Means should be available, while the equipment is used operationally, to determine readily significant drop in performance relative to calibration standard established at the time of installation, and that the equipment is correctly tuned in the absence of targets.

  14 Anti-Clutter Devices

 Suitable means should be provided for the suppression of unwanted echoes, i.e. from sea clutter, rain and other forms of precipitation, clouds and sandstorms. It should be possible to adjust manually and continuously the anti-clutter controls.

  15 Operation

  15.1 The equipment should be capable of being switched on and operated from the place at which the navigator operates the high speed craft.

  15.2 Operator controls should be accessible and easy to identify and use. Where symbols are used they should comply with the recommendation of the Organization on symbols for control on marine navigational radar equipment.

  15.3 After switching from cold, the system should be operational within 4 min.

  15.4 A standby condition should be provided from which the equipment can be brought to an operational condition within 15 s.

  16 Interference

 After installation and adjustment on board, the bearing accuracy as prescribed in these performance standards should be maintained without further adjustment irrespective of the movement of the craft in the earth's magnetic field.

  17 Display Modes

  17.1 The equipment should be capable of operating in relative and true motion.

  17.2 The radar origin should be capable of being off-set at least 50% and not more than 75% of the radius of the display.

  17.3 Where sea or ground stabilization is provided, the accuracy and discrimination of the display should be at least equivalent to that required by these performance standards.

  18 Antenna System

  18.1 The design of the antenna system should enable it to be installed in such a manner that the operational efficiency of the radar system as a whole is not substantially impaired.

  18.2 The antenna system should be so designed as to withstand the forces expected to be experienced by such craft.

  19 Operational with Radar Beacons

  19.1 All radars operating in the 3 cm band should be capable of operating in a horizontally polarized mode.

  19.2 It should be possible to switch off those signal processing facilities which might prevent a radar beacon from being shown on the radar display.

  20 Multiple Radar Installations

 Where two radar installations are required to be carried, they should be so installed that each radar can be operated individually and both can be operated independently.

  21 Interface

  21.1 The radar system should be capable of receiving information from equipment such as gyro-compass, speed and distance measurement equipment (SDME) and electronic position-fixing systems (EPFS) in accordance with international standards.footnote

  21.2 The radar should provide an indication when any input from an external sensor is absent. The radar should also repeat any alarms on status messages concerning the quality of the input data from its external sensors which may influence its operation.

  22 Navigational Information

 The radar display should be capable of presenting in graphical form positions and navigational track lines, e.g. way-points and tracks between way-points in addition to the radar information. The source of the graphical information should be clearly indicated.

  23 Target Trails

 Target trails should be displayed by the radar echoes of targets in the form of synthetic afterglow. The trails may be either relative or true. The true trails may be sea or ground stabilized.


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