ISO/DIS 22090-1:2025(en)

ISO/TC 8/SC 6

Secretariat: JISC

Date: 2025-06-05

Ships and marine technology — Transmitting heading devices (THDs) — Part 1: Gyro-compasses

© ISO 2025

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Contents

Foreword v

Introduction vii

1 Scope 1

2 Normative references 1

3 Terms and definitions 2

4 Abbreviated terms 4

5 Performance requirements 5

5.1 Application 5

5.2 Functionality 5

5.3 Information 5

5.4 Accuracy 5

5.4.1 General 5

5.4.2 Accuracy of transmission data 6

5.4.3 Accuracy under static condition 6

5.4.4 Accuracy under dynamic condition 6

5.5 Interface 6

5.6 Continuous operation 7

5.7 Electromagnetic compatibility 7

5.8 Alert management 7

5.8.1 General 7

5.8.2 Power failure in the gyro-compass (“Power fail” alert) 7

5.8.3 Malfunction of the gyro-compass system (“System fault” alert) 7

5.9 Fore and aft mark 8

5.10 Speed error correction 8

5.11 Status indication 8

5.12 Heading information 8

6 Type tests 8

6.1 General 8

6.2 Settling time test 8

6.3 Static error (settle point error) test 8

6.4 Settle point heading repeatability test 8

6.5 Settling time on a Scorsby table 9

6.6 Scorsby test 9

6.7 Intercardinal motion test 9

6.8 Follow-up error test 10

6.9 Speed error correction test 10

6.10 General requirement test 10

6.10.1 General 10

6.10.2 Voltage variation test 10

6.10.3 Frequency variation test 10

6.10.4 Vibration test 11

6.10.5 Temperature test 12

6.10.6 Damp heat test 12

6.11 Electromagnetic compatibility test 12

6.12 Interface test 12

6.13 Alert management test 12

6.13.1 Basic test for alert management 12

6.13.2 "Power fail” alert or output of a status signal on the EUT power 12

6.13.3 "System fault” alert 13

7 Marking and identification 13

Annex A (normative) Alerts definition for gyro-compasses (THD) 14

Annex B (normative) IEC 61162 interfaces for VDR and other external equipment 15

Bibliography 17

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

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This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee, Subcommittee SC 6, Navigation and ship operations.

This third edition cancels and replaces the second edition (ISO 22090-1:2014), which has been technically revised.

The main changes are as follows:

— Clause 4 (abbreviated terms) has been added;

— in 5.8, requirements related to bridge alert management have been added;

— in 6.1, a requirement for display equipment has been added;

— in 6.13, test method for requirements related to bridge alert management has been added;

— in Annex A, the equivalent requirements in ISO 22090-1 and IMO Resolution have been deleted and the alerts with a standard alert identifier have been defined;

— in Annex B, IEC 61162 interfaces overview has been added;

— the normative references and bibliography have been updated.

A list of all parts in the ISO 22090 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

ISO 22090 consists of the following parts, under the general title Ships and marine technology — Transmitting heading devices (THDs):

— Part 1: Gyro-compasses

— Part 2: Geomagnetic principles

— Part 3: GNSS principles

Introduction

This document is aligned with IMO Resolution MSC.116(73) on performance standards for marine transmitting heading devices (THDs).

Any text in this document which is a citation from the IMO Resolution MSC.116(73), appears in italics. Within these citations, any changes to the original wording of the IMO Resolution MSC.116(73) are written in upright font.

In this document, the following verbal forms are used:

— “shall” indicates a requirement;

— “should” indicates a recommendation;

— “may” indicates a permission;

— “can” indicates a possibility or a capability.

Ships and marine technology — Transmitting heading devices (THDs) — Part 1: Gyro-compasses)

This document specifies general requirements, construction, performance and testing methods of transmitting heading device (THD) using gyro-compasses as required by chapter V, SOLAS 1974 (as amended) and as specified by IMO Resolution MSC.116(73).

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

IEC 60945, Marine navigation and radiocommunication equipment and systems — General requirements — Methods of testing and required test results

IEC 61162‑1, Maritime navigation and radiocommunication equipment and systems — Digital interfaces — Part 1: Single talker and multiple listeners

IEC 61162‑2, Maritime navigation and radiocommunication equipment and systems — Digital interfaces — Part 2: Single talker and multiple listeners, high-speed transmission

IEC 61162‑450, Maritime navigation and radiocommunication equipment and systems - Digital interfaces - Part 450: Multiple talkers and multiple listeners - Ethernet interconnection

IEC 62288, Maritime navigation and radiocommunication equipment and systems — Presentation of navigation-related information on shipborne navigational displays — General requirements, methods of testing and required test results

IEC 62923‑1, Maritime navigation and radiocommunication equipment and systems — Bridge alert management — Part 1: Operational and performance requirements, methods of testing and required test results

IEC 62923‑2, Maritime navigation and radiocommunication equipment and systems — Bridge alert management — Part 2: Alert and cluster identifiers and other additional features

IMO Resolution MSC.116(73), Performance standards for marine transmitting heading devices (THDs)

IMO Resolution MSC.302(87), Adoption of performance standards for bridge alert management

IMO Resolution A.424(XI), Performance standards for gyro-compasses

IMO Resolution A.694(17), General requirements for shipborne radio equipment forming part of the global maritime distress and safety system (GMDSS) and for electronic navigational aids

IMO Resolution A.813(19), General requirements for electromagnetic compatibility (EMC) for all electrical and electronic ship’s equipment

IMO Resolution A.821(19), Performance standards for gyro-compasses for high-speed craft

IMO Resolution A.1021(26), Code on alerts and indicators, 2009

IMO Resolution MSC.191(79), Performance standards for the presentation of navigation-related information on shipborne navigational displays

IMO Resolution MSC 466(101), Amendments to the performance standards for the presentation of navigation-related information on shipborne navigational displays (Resolution MSC.191(79))

For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

3.1

Transmitting heading device (THD)

an electronic device that provides information about the ship’s true heading

Note 1 to entry: Several technologies can be used to detect and transmit heading information. It is illogical to standardize the detection of the heading separately from the transmission of the heading. Therefore, separate parts of this document refer to different technologies. The requirements of this document only apply to gyroscopic technology. Other technologies are covered in other parts of ISO 22090 series.

[SOURCE: IMO Resolution MSC.116(73), 1.1]

3.2

gyro-compass

complete equipment comprising all essential elements of the complete design including both the gyro-compass as heading sensor and the associated heading transmission system

3.3

heading

ship’s heading to be input to the THD function

Note 1 to entry: It is defined by the direction of the vertical projection of the fore-and-aft line of the ship onto the horizontal plane. When measured relative to the true north, magnetic north, or compass north, it is respectively defined as true heading, magnetic heading, or compass heading, and is usually expressed in degrees as a three-figure group, starting from north, in a clockwise direction around the compass card.

[SOURCE: IMO Resolution MSC.116(73), 3.1]

3.4

sensing part

sensing function of detecting any heading information connected to the transmitting part

[SOURCE: IMO Resolution MSC.116(73), 3.2]

3.5

transmitting part

device which receives heading information from the sensing part and converts this to the required accurate signal

[SOURCE: IMO Resolution MSC.116(73), 3.3]

3.6

true heading

horizontal angle between the vertical plane passing through the true meridian and the vertical plane passing through the craft’s fore-and-aft datum line

Note 1 to entry: The true heading is measured from true north (000°) clockwise through 360°.

[SOURCE: IMO Resolution MSC.116(73), 3.4 — note 1 to entry has been added.]

3.7

transmission and resolution error

error which is caused by the method used to transmit the original information to a receiving device

Note 1 to entry: Such a method may have a limited capability to code any possible value of the information, e.g. step output with 1/6° resolution. This error is also caused by the method used inside the THD and at its output to code the information.

[SOURCE: IMO Resolution MSC.116(73), 3.5, modified — note 1 to entry has been added.]

3.8

static error

error caused by any reason and which stays unchanged in value during the operation of the system, measured under static conditions

Note 1 to entry: This static error is the same as the settle point error (3.13)

[SOURCE: IMO Resolution MSC.116(73), 3.6 — note 1 to entry has been added.]

3.9

dynamic error

error caused by dynamic influences acting on the system, such as vibration, roll, pitch, or linear acceleration

Note 1 to entry: This error may have an amplitude and usually a frequency related to the environmental influences and the parameters of the system itself.

Note 2 to entry: This dynamic error is the same as the error (3.14).

[SOURCE: IMO Resolution MSC.116(73), 3.7, modified — notes 1 and 2 to entry have been added.]

3.10

follow-up error

error caused by the delay between the existence of a value to be sensed and the availability of the corresponding signal or data stream at the output of the system

EXAMPLE The difference between the real heading of a turning vessel and the available information at the output of the system.

Note 1 to entry: A follow-up error disappears when the system is static.

[SOURCE: IMO Resolution MSC.116(73), 3.8, modified — EXAMPLE and notes 1 to entry have been added.]

3.11

settled

stable situation when any three readings taken at intervals of 30 min are within a band of 0,7°, with the compass level and stationary

Note 1 to entry: The settling time is the elapsed time between the time of switch-on at the initial heading error and the third recording of the settle.

3.12

settle point heading

mean value of ten readings taken at 20 min intervals after the compass has settled (3.11)

3.13

settle point error

difference between the settle point heading (3.12) and the true heading (3.6)

Note 1 to entry: This settle point error is the same as the static error (3.8)

3.14

error

difference between the observed value and the settle point heading (3.12)

Note 1 to entry: This error is the same as the dynamic error (3.9)

3.15

latitude error

error to which some gyro-compasses (3.2) are subject, the magnitude and sign of which depend upon the local latitude

Note 1 to entry: Means are provided for correcting this error.

3.16

speed error

error to which gyro-compasses (3.2) are subject, the magnitude and sign of which depend upon the speed, course, and latitude of the ship

Note 1 to entry: Means are provided for correcting this error.

3.17

master compass

main compass unit which supplies the heading information to the transmitting part or other navigational aids

3.18

Scorsby table

test machine which enables a platform to oscillate independently about three axes

Note 1 to entry: it is used to simulate the motion of a ship

3.19

intercardinal motion

representing an integral motion of the ship and is used for error test within motion in dynamic simulation test

3.20

bridge alert management (BAM)

overall concept for management, handling and harmonized presentation of alerts on the bridge

[SOURCE: IMO Resolution MSC.302(87), Appendix 1]

3.21

central alert management system (CAM system)

combined functionality of the central alert management and the central alert management human machine interface

[SOURCE: IMO Resolution MSC.302(87), Appendix 1]

For the purposes of this document, the following abbreviated terms apply.

Transmitting heading device(THD) shall comply with IMO Resolution MSC.116(73).

In accordance with IMO Resolution MSC.116(73), 1.2, in addition to the general requirements contained in IMO Resolution A.694(17) to which IEC 60945 is associated and the relevant standard for the sensing part used, the THD equipment shall comply with the following minimum requirements.

In accordance with IMO Resolution MSC.116(73), 1.3 where the IMO performance standards that apply to the sensing part do not specify a geographical operating area that the THD shall operate

a) at maximum rate of turn 20°/s and

b) from 70° latitude south to 70° latitude north as minimum.

In accordance with IMO Resolution MSC.116(73), 2.1, the THDs complying with the requirements contained in this document can be used for heading information as contained in chapter V of the SOLAS Convention.

However, ships within a speed range of 30 kn^[1] to 70 kn¹⁾ shall comply with the requirements of IMO Resolution A.821(19).

In accordance with IMO Resolution MSC.116(73), 2.2, in addition, such THD shall meet the dynamic requirements contained in the HSC Code, chapter 13 for the carriage of a suitable device providing heading information.

In this document, the gyro-compass is specified as the function of THD.

In accordance with IMO Resolution MSC.116(73), 4.1.1, the THD generates a heading signal and outputs a suitable signal for other devices.

In accordance with IMO Resolution MSC.116(73), 4.1.2, any sensing part may be included in the device.

In accordance with IMO Resolution MSC.116(73), 4.1.3, if any correcting devices or parameters have been associated, they shall be protected against inadvertent operation.

In accordance with IMO Resolution MSC.116(73), 4.2.1, all displays with the exception of the sensor, and all outputs of heading shall indicate true heading.

Indication shall be displayed, readable to a tenth of a degree.

In accordance with IMO Resolution MSC.116(73), 4.2.2, manually entered values used for electronic correction shall be indicated by adequate means.

In accordance with IMO Resolution MSC.116(73), 4.3.1, the THD shall be tested for accuracy with the sensing part connected. If the sensing part is so designed that it is included in the transmitting part, the equipment shall be tested at all parts.

In accordance with IMO Resolution MSC.116(73), 4.3.2, the THD shall meet at least the following accuracy at the output of the device under sea conditions as specified in IMO Resolution A.424(XI) or A.821(19) as applicable.

In accordance with IMO Resolution MSC.116(73), 4.3.2.1, the transmission error, including the resolution error, shall be less than ±0,2°.

Settling time under static condition

When switched on in accordance with the manufacturer's instructions, the compass shall settle within 6 h.

Static error (settle point error)

In accordance with IMO Resolution MSC.116(73), 4.3.2.2, the static error (settle point error) at any heading shall be less than ±1,0° × secant latitude, and the RMS value of the differences between individual heading indications and the mean value shall be less than 0,35° × secant latitude.

The repeatability of settle point error from one run-up to another shall be within 0,35° × secant latitude.

Settling time under dynamic condition

When switched on in accordance with the manufacturer's instructions, the compass shall settle within 6 h when rolling and pitching with simple harmonic motion of any period between 6 s and 15 s, a maximum angle of 5°, and a maximum horizontal acceleration of 0,22 m/s².

Dynamic error

In accordance with IMO Resolution MSC.116(73), 4.3.2.3 the dynamic error amplitude shall be less than ±1,5° × secant latitude. The dynamic error frequency shall be less than 0,033 Hz equivalent to a period not shorter than 30 s if the amplitude of the dynamic error exceeds ±0,5°

Performance under operational condition

In latitudes of up to 70°N or 70°S in a ship operating within a latitude band of 10°

— the residual steady-state error, after correction for speed and course influences at a speed of 30 kn¹, shall not exceed ±0,35° × secant latitude,

— the maximum error due to a rapid alteration of speed of 30 kn¹⁾ shall be kept to a minimum, and shall not exceed ±3°. The horizontal acceleration shall not exceed 2,0 m/s², and

— the error due to a rapid alteration of course of 180° up to maximum rate of turn of 20°/s in heading up to a speed of 30 kn¹⁾ shall not exceed ±4,5°. The horizontal acceleration shall not exceed 2,0 m/s².

Follow-up error

In accordance with IMO Resolution MSC.116(73), 4.3.2.4, the follow-up error for different rates of turn shall be

— less than ±0,5° up to a rate of 10°/s, and

— less than ±1,5° up to a rate of between 10°/s and 20°/s.

NOTE 1 See Annex B.

In accordance with IMO Resolution MSC.116(73), 4.4, at least one output shall be in accordance with the relevant international marine interface standard.

The THD shall provide interface facilities which meet IEC 61162-1, IEC 61162-2 or IEC 61162-450.

The THD equipment shall provide an appropriate data source and at least one output of heading information. The heading output shall be updated at a rate of once every 20 ms. The THS sentence detailed in IEC 61162-1 shall be provided for heading information.

NOTE 2 THS refers a sentence formatter which is described in IEC 61162-1.

The Sentences from IEC 61162-1 shall be in accordance with Annex B.

The equipment shall be capable of continuous operation under conditions of vibration, humidity, change of temperature, and variations of the power supply, as specified in 6.10.

In accordance with IMO Resolution MSC.116(73), 5, the device, with regard to electromagnetic interference and immunity, shall in addition to IMO Resolution A.694(17), comply with IMO Resolution A.813(19).

In accordance with IMO Resolution MSC116(73), 6, an alert shall be provided to indicate malfunctions of the THD or a failure of the power supply.

If the gyro-compass uses display equipment for alert management, it shall comply with IMO Resolution MSC.191(79), as amended by IMO Resolution MSC.466(101), and with IEC 62288.

The general presentation, handling and communication for alerts shall comply with the requirements stated in IMO Resolution MSC.302(87), IEC 62923-1, Module A and Module C, and IEC 62923-2, as a minimum.

The alerts with a standard alert identifier for gyro-compasses are specified in Table A.1.

NOTE 1 Alert titles and alert description texts used in Table A.1 and in the body text of this document are not mandatory alert titles and alert description texts, but are regarded as guidance. Alert titles and alert description texts used in the body text of this document are therefore indicated between double quotation marks (“ “).

The manufacturer of the gyro-compass shall declare the EUT function type for the bridge alert management (BAM) compliance test.

NOTE 2 According to the EUT function type, the relevant test set-up and test items are specified in BAM test standards. Refer to IEC 62923-1: EUT function types, Test methods, Module A and Module C.

In the case of power failure of the gyro-compass, a status signal (e.g. by normally closed contact) shall be provided to enable external equipment to raise the appropriate alert.

If the gyro-compass has another power supply for backup and can use display equipment during failure of one power supply, the “power fail” alert may be provided as specified in Table A.1.

When the self-diagnosis function of the gyro-compass detects the major malfunction of the system, the “System fault” alert with an appropriate priority or the minimum presentation indicating the cause of failure shall be activated as specified in Table A.1.

In the case of the malfunction whereby the gyro-compass system cannot operate at all, the status signal (e.g. by normally closed contact) shall be output as specified in 5.8.2 so that external equipment can raise a proper alert.

The compass shall be marked to facilitate installation in fore and aft line of the ship.

Means shall be provided for correcting the errors induced by speed and latitude. An approved accurate speed source shall be used for automatic speed error corrections.

Status shall be indicated that the gyro-compass is ready to use.

The THD shall provide true heading information to the other navigational equipment.

Heading information shall be provided as an output with accuracy as defined in 5.4.

Where the EUT includes repeater compasses, at least one repeater compass of the EUT is energized and aligned with the master compass throughout the course of the environmental tests. Each remaining repeater compass output is connected to a normal load or to suitable impedance representing a normal load, supplied by the manufacturer. However, the associated repeater compass is not subject to this test.

If the EUT uses display equipment, confirm by inspection of documented evidence that the EUT complies with IEC 62288.

Confirm by inspection of documented evidence that the EUT complies with 5.2, 5.3, 5.9 and 5.11.

Confirm by inspection of documented evidence that accuracy of transmission data of the EUT complies with 5.4.2.

The master compass of the EUT is securely positioned on a nominally level and stationary base. It is energized from nominal value power supplies and started in accordance with the manufacturer's instructions from an initial heading error (to east) of 30° or more.

Confirm by observation that the settling time meets the requirement specified in 5.4.3.1.

When the master compass of the EUT has settled, confirm by observation that the static error conforms to the requirements specified in 5.4.3.2.

The master compass of the EUT is started in accordance with the manufacturer's instructions from an initial heading error (to east) of 30° or more and is allowed to settle.

The settle point heading is determined. The master compass of the EUT is then switched off for a period of not less than 12 h and not more than 7 days. It is then started again from an initial heading error (to west) of 30° or more, and the settle point heading is measured again.

The master compass of the EUT is then switched off for a period of not less than 12 h and not more than 7 days. It is started again from an initial heading error (to east) of 30° or more and the settle point heading is determined. The three values of the obtained settle point heading are recorded. It is confirmed by observation that the difference between any two values does not exceed 0,35° × secant latitude.

NOTE If this test follows the text described in 6.3, then the “settle” obtained from that text can be used as the first value required by this repeatability test provided that the second “settle” follows a switch-off period of not less than 12 h and not more than 7 days.

The master compass of the EUT is mounted on a Scorsby table with the master compass fore-and-aft line, nominally parallel with one axis of the table, which is designated the roll axis.

The other nominally horizontal axis (at right angles to the first axis) is designated the pitch axis.

The EUT is switched on in accordance with the manufacturer's instructions with the following nominal simple harmonic table motions:

— roll axis: peak amplitude 5° ± 1°, period 15 s ± 1 s;

— pitch axis: peak amplitude 5° ± 1°, period 6 s ± 1 s.

Confirm by observation that the settling time measured between switch-on and compass settle conforms to the requirements specified in 5.4.4.1.

NOTE THD readings to determine the settle condition can be taken with the Scorsby table stationary and nominally level, and with a minimum delay before resuming the specified table motion.

The master compass of the EUT is settled on the Scorsby table with the table stationary, nominally level and its roll axis aligned north–south within ±1°.

The compass fore and aft mark is aligned to within ±1° of the table roll axis. The following nominal simple harmonic motions are applied simultaneously to the three axes of the table for 25 min:

— roll axis: peak amplitude 20° ± 2°, period 10 s ± 1 s;

— pitch axis: peak amplitude 10° ± 2°, period 6 s ± 1 s;

— yaw axis: peak amplitude 5° ± 1°, period 15 s ± 1 s.

At the end of 25 min, the table motion is stopped, the table is returned to its original position and the THD heading is recorded without delay.

This test is repeated with the roll axis of the motion table aligned at 45° ± 1°, at 90° ± 1, and at 315° ± 1°. At each of these headings, the compass settle point is determined before commencing the table motion. Any change of heading indication by the compass between the settle point heading immediately prior to the motion and the heading at the conclusion of the motion is recorded as an error due to motion.

In each of the four tests, confirm by observation that error due to the motion is less than ±1,5° × secant latitude.

Confirm by observation that any horizontal accelerations applied during this test does not exceed 1 m/s²

The master compass of the EUT is securely mounted on a device having the ability to move with nominal simple harmonic motion such that the component of motion in a horizontal plane has a peak acceleration of 1,0 m/s² ± 0,1 m/s². The direction of motion of the device in the horizontal plane is an intercardinal direction to within ±3°.

When so mounted, the master compass is settled and the settle point heading is obtained with the device stationary and nominally levelled. The device then is submitted to the motion described previously having a peak acceleration of 1,0 m/s² ± 0,1 m/s² with a periodic time of not less than 3 s, for a duration of 2 h. Any difference between the THD heading recorded during the motion and the settle point heading prior to the motion is considered as due to the motion. Confirm by observation that this difference does not exceed 1,5° × secant latitude.

Confirm by observation that the THD heading recorded during the motion discounts any modulation at frequencies equal to or higher than the frequency of the applied motion.

The master compass of the EUT on a level rotary table is turned at a rate not greater than 10°/s, to read data both of THD output and angle of the table at, at least 5° intervals during this test.

Confirm by observation that the maximum follow-up errors conform to the requirements specified in 5.4.4.4.

The table and master compass of the EUT are turned at a rate not greater than 20°/s, to read data both of THD output and angle of the table at, at least, 5° intervals during this test.

Confirm by observation that the maximum follow-up errors conform to the requirements specified in 5.4.4.4.

With the master compass of the EUT mounted on a level and stationary base and the fore and aft mark of the compass aligned to north, the master compass of the EUT is settled and the settled point heading is recorded.

A speed signal of 30 kn¹⁾ is applied to the EUT, and allowed to resettle.

Confirm by observation that the difference between the settle point heading obtained and the settle point heading initially recorded agrees with the value computed theoretically for the latitude of the test to within 0,35° × secant latitude.

For these tests, the datum from which settle point variations are measured is the settle point heading obtained in the absence of the particular environmental condition to be applied.

The supply voltage is set to 10 % above the nominal value for 3 h, during which time the THD heading is recorded at 20 min intervals. The supply voltage then is set to a value 10 % below nominal for 3 h, and the THD heading again recorded at 20 min intervals.

Confirm by observation that none of the recorded headings departs from the original datum by more than 1,5° × secant latitude.

In the case of AC supply, the frequency is set to 5 % above the nominal value for 3 h, during which time the THD heading is recorded at 20 min intervals. The supply frequency then is set to a value 5 % below nominal for 3 h and the THD heading again recorded at 20 min intervals.

Confirm by observation that none of the recorded headings departs from the original datum by more than 1,5° × secant latitude.

Vibration test of master compass

In all of these tests, the direction of the master compass fore and aft mark is+30° ± 1° to the meridian.

The master compass of the EUT is subjected to the vibration described below. Three separate tests are carried out, the direction of vibration being:

a) +30° ± 1° to the meridian and horizontal;

b) −60° ± 1° to the meridian and horizontal;

c) vertical.

In each case, the master compass of the EUT is settled initially and then the vibration is applied at the lowest frequency, holding the appropriate vibration amplitude for a period of 25 min. At the end of that period, the frequency and amplitude are changed to the next value shown in Table 1 and held for a further 25 min. This process continues until the entire frequency range has been covered.

Table 1 — Frequency and amplitude for vibration test of master compass

The indicated heading is recorded at the end of each period. Confirm by observation that any difference between these recorded heading and the datum settle point heading is not more than 1,5° × secant latitude during the test.

NOTE Provision can be made to reduce or nullify any adverse effect on the equipment performance caused by the presence of any electromagnetic field due to the vibration unit.

Vibration test of compass equipment other than master compass

This equipment, complete with any shock absorbers which are part of it, is secured by its normal means of support to the vibration table. It then is connected in its normal electrical configuration to the master compass. The master compass is then switched on in accordance with the manufacturer's instructions and its settle point heading ascertained and recorded.

The equipment on the vibration table is then vibrated vertically at all frequencies between:

a) 5 Hz and 13,2 Hz with an amplitude of 1,0 mm;

b) 13,2 Hz and 40 Hz with a maximum acceleration of (0,7 × 9,8) m/s²,

taking at least 25 min to cover each frequency range.

This whole procedure is repeated when the equipment is vibrated in two mutually perpendicular directions in the horizontal plane.

Confirm by observation that there is no electrical or mechanical failure during any part of this series of tests.

The indicated heading is recorded at the end of each period.

Confirm by observation that any difference between these recorded heading and the datum settle point heading is not more than 1,5° × secant latitude during the test.

The EUT is placed in a chamber at normal room temperature, switched on and allowed to settle. The settle point heading is obtained and recorded. The temperature of the chamber is then raised to 45 °C ± 2 °C and maintained for a period of 3 h. At the end of this period, the THD heading indication again is recorded. The temperature of the chamber is then reduced to 0 °C ± 2 °C and maintained at this temperature for 3 h. At the end of this period, the THD heading indication is recorded once more.

Confirm by observation that neither of the recorded heading indications differs from the datum settle point heading by more than 1,5° × secant latitude.

NOTE When the temperature of the chamber is being changed, it does not alter by a rate which exceeds 45 °C/h.

The EUT is placed in a chamber at normal room temperature and humidity, switched on and allowed to settle. The settle point heading is obtained and recorded. Over a period of 3 h ± 0,5 h the temperature and relative humidity of the chamber are then raised steadily to 40 °C ± 2 °C, and 93 % ± 3 %, respectively. These conditions are maintained for a further period of 3 h ± 0,5 h.

Confirm by observation that the THD indication at the end of this test does not differ from the datum settle point heading by more than 1,5° × secant latitude

Confirm by observation that electromagnetic interference and immunity are tested in accordance with IEC 60945.

NOTE See 5.5.

The interface facilities shall be subjected to the tests specified in IEC 61162-1, IEC 61162-2 or IEC 61162-450. Observe the heading output rate specified in IEC 61162-2 and ensure that it is updated at least once every 20 ms.

NOTE See 5.8.

Confirm by inspection of documented evidence that the EUT complies with IEC 62923-1, Module A and Module C, and with IEC 62923-2.

The sentences from IEC 61162-1 shall be in accordance with Annex B.

NOTE See 5.8.2 and Table A.1.

The method of testing and required test results of “power fail” alert or the output of a status signal on the EUT power is as follows:

a) Connect power to the power supply/supplies of the EUT.

b) Remove one power to the EUT.

In case the EUT blacks out due to power failure, confirm by observation that the EUT provides a status signal output as specified in 5.8.2.

Optionally, the EUT may activate a “Power fail” alert of an appropriate priority by using backup power supply.

NOTE See 5.8.3 and Table A.1.

The method of testing and required test results of "system fault" alert is as follows:

a) Create a malfunction in the system that has a severe effect on the true heading.

b) Confirm by observation that the EUT activates a “System fault” alert of warning priority.

Each unit of the equipment shall be marked with the minimum safe distance at which it can be mounted from a standard and a steering magnetic compass. The safe distance shall be measured in accordance with IEC 60945.

1. 
   (normative)
   
   Alerts definition for gyro-compasses (THD)

The alerts with a standard alert identifier for the gyro-compass (GC) are specified in Table A.1.

Table A.1 — Classification of gyro-compass required alerts

1. 
   (normative)
   
   IEC 61162 interfaces for VDR and other external equipment

The sentences specified in IEC 61162 for transmitting and receiving data for the gyro-compass are specified in Tables B.1 and B.2. The manufacturer shall specify which part of IEC 61162 supports each physical interface.

Figure B.1 shows the required logical interfaces. If more than one logical interface is implemented on a single physical interface, then all aspects of each logical interface, including alert communication, heartbeat, etc., shall be distinguishable from those of other logical interfaces implemented on the same physical interface.

Figure B.1 — Gyro-compass logical interfaces

NOTE The speed from a GNSS can be used for the correction of speed error.

Table B.1 — Sentences from IEC 61162-1 transmitted by the gyro-compass

Table B.2 — Sentences from IEC 61162-1 received by the gyro-compass

Bibliography

[1] ISO 8728, Ships and marine technology — Marine gyro-compasses

[2] ISO 16328, Ships and marine technology — Gyro-compasses for high-speed craft

[3] IEC 61162‑3, Maritime navigation and radiocommunication equipment and systems — Digital interfaces — Part 3: Serial data instrument network

[4] International Convention for the Safety of Life at Sea (SOLAS) 1974 (amended)

[5] NAV 47/13, Repot to the maritime safety committee, Performance standards for marine transmitting heading devices (THDs), 7.24, 7.25

[6] MSC 75/24, Repot to the maritime safety committee on its seventy-fifth session, New and amended performance standards for navigation for equipment, 6.21

1. The equivalence to SI units: “1 kn = 1,852 km/h” ↑