What is the difference between AMRD Group A and AMRD Group B?.

AMRD Group A are identified as those that enhance the safety of navigation, and AMRD Group B are those that do not enhance the safety of navigation. The International Maritime Organisation (IMO) is the responsible organisation.

Group A are:

• Man overboard devices using VHF DSC (Class-M)
• Mobile AIDS to Navigation (Mobile AtoN)

A Man Overboard (MOB) using VHF DSC (Class-M) is a personal radio equipment (PRE) which alerts via Digital Selective Calling (DSC) and is tracked by the Automatic Identification System (AIS).

Only AMRD Group A are permitted to use Radio Regulations (RR) Appendix 18 frequencies which are allocated for DSC (Channel 70, 156.525 MHz) and for the AIS (AIS 1, 161.975 MHz) and (AIS 2, 162.025 MHz).

What is in AMRD Group B

All other applications of AMRD including MOB without DSC, fishnet marker, diver locating device etc are in AMRD Group B. The IMO suggested that legacy AMRD, categorised as Group B but using VHF channels AIS 1 and AIS 2, should no longer be placed on the market.