NAVDAT

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Overview

NAVDAT is a technology under consideration by the IMO as part of the modernisation plan for the GMDSS. It is a digital system for broadcasting maritime safety and security-related information from shore-to-ship, similar in functionality to NAVTEX (the existing MF Maritime Safety Information system). It aims to address the limited capacity of NAVTEX and also allows for the possibility of encryption.

NAVDAT has been specified to operate in both MF (500kHz) and HF frequency bands. It uses a time-slot allocation similar to the NAVTEX system. The system uses orthogonal frequency division multiplexing (OFDM) which is a modulation technology for digital transmissions, and every subcarrier is modulated using Quadrature amplitude modulation (QAM), as 64-QAM, 16-QAM or 4-QAM. A 10 kHz channel is the necessary bandwidth for each system.

WRC-19 Outcome

Agenda item 1.8 - Issue A: Modernisation of GMDSS

The aim of Agenda item 1.8 - Issue A was to make provisions for the introduction of NAVDAT.

This was achieved by modifying Article 5 No. 5.79 in the Radio Regulations to say that the frequency bands 415-495 kHz and 505-526.5 kHz may also be used for the NAVDAT system, and adding a footnote in Appendix 17 of the Radio Regulations to say that the 4, 6, 8, 12, 16 and 22 MHz bands may also be used by the NAVDAT system (Appendix 17 (Rev. WRC-19)).

Performance standard, testing standard & carriage requirement

• Recommendation ITU-R M.2010: Characteristics of a digital system, named Navigational Data for broadcasting maritime safety and security related information from shore-to-ship in the 500 kHz band
• Recommendation ITU-R M.2058-0: Characteristics of a digital system, named navigational data for broadcasting maritime safety and security related information from shore-to-ship in the maritime HF frequency band

Typical system components

• Component 1
• Component 2...

Detailed requirements

(Performance Standard)

Defintions
Term	Defition
Term 2	Defintion 2
Module A - Title
Section title	Para number	Requirement

See also

NAVTEX