IEC 61097-9:1997

Overview

IEC 61097-9:1997 is an International Electrotechnical Commission (IEC) standard for the Global Maritime Distress and Safety System (GMDSS). It specifies the minimum operational and performance requirements and the methods of testing for shipborne transmitters and receivers operating in the medium frequency (MF) and high frequency (HF) bands that are suitable for:

• Telephony (voice)
• Digital Selective Calling (DSC)
• Narrow Band Direct Printing (NBDP)

The standard covers equipment intended to operate either in the MF band only or in both MF and HF bands and defines required test results to demonstrate compliance.

Key topics and requirements

IEC 61097-9 focuses on practical performance, safety and interoperability requirements for maritime radio equipment. Key technical topics include:

• Performance requirements: frequency accuracy and stability, usable sensitivity, output power, audio response and carrier suppression for SSB telephony.
• Transmitter tests: frequency error, output power and intermodulation, unwanted frequency modulation, residual RF noise, spurious emissions and continuous-operation protection.
• Receiver tests: maximum usable sensitivity, adjacent-channel selectivity, blocking, cross-modulation, intermodulation, spurious response rejection and AGC (automatic gain control) behaviour.
• Digital modes: timing and switching requirements for DSC and NBDP, and residual modulation limits for data modes.
• Alarm & control functions: radiotelephone alarm signal generator, distress control interfaces and control panel priority arrangements.
• Environmental and EMC testing: immunity, conducted spurious emissions, acoustic noise, compass safe distance and environmental durability.
• Safety and interfaces: power supply, antenna static protection and operator controls/labels.

These requirements are supported by detailed methods of testing and required test results (see clauses on test conditions, performance checks and general measurement conditions).

Applications and who uses it

IEC 61097-9 is essential for stakeholders involved in maritime radio equipment design, certification and operation:

• Manufacturers of shipborne MF/HF radio transmitters and receivers (telephony, DSC, NBDP)
• Type-approval and certification bodies and maritime regulatory authorities enforcing GMDSS compliance
• Maritime electronics test laboratories performing EMC, environmental and performance tests
• Shipyards and ship operators procuring compliant radio communication equipment
• Marine radio engineers and surveyors verifying installation and performance

Compliance ensures reliable voice and data distress communications, interoperability across the GMDSS and adherence to international maritime safety requirements.

Related standards

• IEC 60050 (IEV) - Electrotechnical vocabulary
• IEC 60027 / IEC 60417 / IEC 60617 - symbols and graphical signs
• ITU‑R recommendations referenced for NBDP/DSC protocols (e.g., ITU‑R M.625)

Keywords: IEC 61097-9, GMDSS, MF HF, shipborne transmitters, DSC, NBDP, maritime radio equipment, performance requirements, methods of testing, maritime safety.