Where does the standard define the GPS antenna requirement and how does it work across Icom radios?

The ITU-R M.493 standard mandates integrated GNSS/GPS receivers for Class D DSC VHF radios. In Europe, this is implemented under the ETSI EN 301 025 standard, which stipulates that the system must support an external antenna option. This guarantees that regardless of whether a vessel is constructed of fibre glass, wood, steel, or aluminium that the radio can always maintain an unobstructed view of the sky for accurate location data during a DSC distress alert.

To give boatowner the best flexibility for their vessel's wheelhouse or helm layout, Icom radios meet these requirements in two ways:

• Dedicated External Antenna Setup (IC-M330GE, IC-M423GE & IC-M605)
These compact and flush-mount units feature an integrated internal GPS receiver paired with a high-sensitivity external puck antenna included in the box. This allows you to route the antenna directly outside or onto a gantry for maximum satellite acquisition, regardless of where the radio body is mounted inside the cabin.

• Internal Antenna with External Capability (IC-M510 series)
These advanced models feature a fully integrated internal GPS receiver and internal antenna built directly into the housing, offering a sleek, all-in-one installation for most standard fibre glass boats. However, to remain fully compliant with ITU/ETSI standards for wheelhouses that block GPS signals (such as steel or carbon-hulled vessels), they also feature a rear connection port for an optional external GPS antenna if needed.

By offering both approaches, Icom ensures complete compliance with global maritime standards while giving boaters the flexibility to choose the ideal setup for their vessel.

For more details about our marine VHF range please visit our 'Marine Radio Pages'.

03/08/2026