This part of ISO 22090 specifies general requirements, the construction, performance and testing of Transmitting Heading Device using GNSS principle required by chapter V, SOLAS 1974 (as amended).

　

A transmitting heading device (THD) is an electric device that provides information about the ship's true heading.

　

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.

　

Where the IMO performance standards that apply to the sensing part do not specify a geographical operating area the THD shall operate;

　

　

The THDs complying with the requirements contained in this part of ISO 22090 can be used for heading information as contained in Chapter V of the SOLAS Convention.

　

In addition such THDs shall meet the dynamic requirements contained in the HSC Code, chapter 13 for the carriage of a suitable device providing heading information.

　

NOTE 1　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 part of ISO 22090 refer to different technologies. The requirements of this part of ISO 22090 only apply to the principle of the GNSS one. Other technologies are covered in other parts of ISO 22090.

　

NOTE 2　All requirements that are extracted from the recommendation of IMO Resolution MSC. 116 (73) on performance standards for transmitting heading devices are printed in italics.

　

The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of ISO 22090. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 22090 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards.

　

ISO 694, Ships and marine technology - Positioning of magnetic compasses in ships

　

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

　

IEC 61162, Maritime navigation and radiocommunication equipment and systems - Digital interfaces

　

International Convention on Safety of Life at Sea (SOLAS) 1974 (amended)

　

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

　

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

　

　

For the purposes of this part of ISO 22090, the following terms and definitions apply.

　

　

NOTE　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.

　

a sensing function of detecting any heading information or information of directional source(i.e. GNSS antenna) connected to the transmitting part

　

device which receives a heading information or information of directional source from the sensing part and converts this to the required accurate signal

　

horizontal angle between the vertical plane passing through the true meridian and the vertical plane passing a through the craft's fore and aft datum line, It is measured from the true north (000°) clockwise through 360°

　

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

　

　

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

　

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

　

error which is 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; . This error is e.g. the difference between the real heading of turning vessel and the available information at the output of the system

　

NOTE　A follow-up error disappears when the system is static

　

time required to reach the state that the THD can output heading information with an accuracy specified in 6.3 below since switched on the THD with fully usable satellite almanac.

　

RMS of output headings taken at interval of 1 minute shall be within 1,5°95%

　

difference between the settled point heading and the true heading

　

test machine which enables a platform to oscillate independently about three axes. It is used to simulate the motion of a ship

　

test machine which independently oscillates a platform about three axes. It is used to simulate the motion of a ship

　

the principles of the THDs in order to determine the own ship heading by measuring an RF carrier phase in the GNSS signals

　

4.1.1 The THD is an electronic device which receives a heading sensor signal and generates a suitable output signal for other devices.

　

4.1.2 Any sensor part may be included in the device.

　

4.1.3 Any correcting devices or parameters shall be protected against inadvertent operation.

　

4.1.4 Manually settable values used for electronic correction shall be indicatable by adequate means.

　

　

The THD shall be capable of continuous operation under conditions of vibration, humidity, and change of temperature as specified in 6.8.

　

　

All displays with the exception of the sensor, and all outputs of heading shall indicate true heading.

　

　

The THD shall have a means to align the sensing direction to the ship's fore and aft line.

　

　

A brief interruption of GNSS signal shall be compensated so as to maintain the heading accuracy within ± 1,5°for the duration of 60 seconds at least.

　

　

Settling time shall be less than 10 minutes in static condition.

　

　

The THD shall update a new heading at least once every [50]ms.

　

At least one The digital serial output shall comply with IEC 61162.

　

　

An alarm shall be provided on the following conditions.

　

― malfunction of the THD

　

― failure of power supply and

　

― continuous GNSS signal interruption over [60] seconds.

　

[The THD is recommended to have a means to output the failure status to an associate equipment.]

　

　

At least one The digital serial output shall comply with IEC 61162.

　

The THD shall meet at least the following accuracy at the output of the device under sea condition as specified in IMO Resolution A.424 (XI) or A.821 (19) as applicable.

　

　

The transmission error including the resolution error shall be less than ±0.2°.

　

　

The static error (settle point error) as defined in 3.5 at any heading shall be within 1,0° 95%.

　

　

The dynamic error as defined in 3.6 shall be within 1,5° 95%.

　

　

The follow-up error as defined in 3.7 for different rates of turn shall be: