Glossary of VHF radio and associated tech terminology

Significant improvements in a number of areas in recent years have seen handheld VHF marine radios move from being purely portable communications devices to something altogether more useful. As technology has shrunk, battery life improved and screens become clearer, handheld VHFs can now offer many of the safety features that used to be available only on fixed marine radios. As a sailor who often uses marine aircraft, you should know some of its technical terms.

AIS – Automatic Identification System

A system that transmits a vessels particulars by VHF signal to other receivers within VHF range. This includes the MMSI, vessel name, speed, course over ground and sometimes other info too. Units also give a CPA or closest point of approach which aids in navigation where there’s high traffic and collision avoidance.

Callsign

Unique letter/number vessel identification number issued in the UK by OfCom

CG66

Coastguard Yacht and Boat Safety Scheme form

DSC

Digital Selective Calling, using VHF ch70 for automated distress alerts. Requires a unit to be GPS enabled.

Dual watch

A function allowing you to monitor CH16 and one other channel at the same time.

Tri Watch

A function allowing you to monitor two self selected channels plus Ch16

GMDSS

Global Maritime Distress and Safety System

GPS

Global Positioning System

Mayday

Globally recognised universal Distress signal

MMSI

9-digit Maritime Mobile Service Identity provided in the UK by OfCom

PTT

Press to transmit

SAR

Search and Rescue

Securite

Safety signal. Origin French – sécurité – safety.

Simplex

Radio working that uses the same frequency for transmitting and receiving.

Squelch

A radio control that suppresses background interference.

Traffic

Radio messages

TX

Transmitting

Receiving

UKCG

UK Coastguard

VHF

Very High Frequency

Importance of Using Marine VHF Radio on Inland Waterways

Handheld VHF marine radio design is improving with new functions added every year.