VHFDSCkommunikasjonsutstyr

VHF DSC communication refers to the use of Digital Selective Calling on the VHF marine radio band to originate distress, urgency, safety, and other calls without voice transmission. It operates primarily on channel 70 (156.525 MHz) for DSC traffic, while traditional voice calls use channels such as channel 16 (156.8 MHz) for hailing. Each vessel equipped with VHF DSC is assigned a Maritime Mobile Service Identity (MMSI), a unique nine-digit number that identifies ship stations, coast stations, or groups of vessels. DSC messages indicate the call type (distress, safety, urgency, or individual/group/all ships) and may include vessel information such as name and position when available from connected GPS.

In practice, a DSC call is initiated by selecting the intended recipient’s MMSI and the desired call type. The device transmits a digital alert on channel 70, which alerts the receiving station or vessel. If the receiving unit is configured to respond, it will acknowledge the call; a distress alert triggers emergency procedures and automatic attention from nearby stations. DSC also enables group and all-ships calls, allowing rapid coordination across a navigational area. When a distress incident is declared, the alert may include or be augmented by the vessel’s position, course, and speed, depending on GPS integration.

Operational context and limitations: VHF DSC is a core component of the Global Maritime Distress and Safety System (GMDSS), designed to improve reliability and speed of initial contact and acknowledgement. It enhances routine and emergency communications but is not a substitute for voice channels, which remain essential for follow-up coordination. Effective use relies on accurate MMSI data, properly maintained equipment, and crew training. Regional implementations and device capabilities can vary, with some DSC devices offering richer data transmission when connected to GPS.