The Ins And Outs Of Marine VHF By: Joe Minick VHF RADIO GLOSSARY Automatic Identification System (AIS): A system used by ships and Vessel Traffic Service (VTS) systems to aid in the identification of vessels at sea. AIS helps to resolve the difficulty of identifying ships by providing an automatic radio exchange of ID, position, course, and speed with other nearby AIS-equipped vessels and VTS stations. Digital selective calling (DSC): A digital hailing or calling system used with VHF, MF, and HF radio systems to establish communications with other DSC-equipped vessels or coast stations. A two-tone d…
The Ins And Outs Of Marine VHF
By: Joe Minick
VHF RADIO GLOSSARY
Automatic Identification System(AIS): A system used by ships and Vessel Traffic Service (VTS) systems to aid in the identification of vessels at sea. AIS helps to resolve the difficulty of identifying ships by providing an automatic radio exchange of ID, position, course, and speed with other nearby AIS-equipped vessels and VTS stations.
Digital selective calling (DSC): A digital hailing or calling system used with VHF, MF, and HF radio systems to establish communications with other DSC-equipped vessels or coast stations. A two-tone digital signaling protocol can be programmed to call a particular station, a group of stations, or all stations within range or in a particular geographic area.
Emergency position-indicating radio beacon (EPIRB): An emergency radio beacon capable of transmitting a signal that can be used to determine the ship’s position. Its primary function is to alert rescue facilities to a vessel in distress and aid in determining its location.
Ionosphere: A series of concentric layers in the upper atmosphere of the Earth. The ionosphere begins at an altitude of 30-50 miles (50-80 kilometers) and extends 250-370 miles (400-600 kilometers) above the Earth’s surface. Within these layers, defined as D, E, and F, the sun’s radiation creates enough ions (charged particles) to significantly affect radio propagation by reflecting lower frequency signals back to Earth but allowing VHF and higher frequency signals to pass through.
Radio propagation: A term used to explain how radio waves behave when they are transmitted, or propagated, from one point on the Earth to another.
Temperature inversion: In meteorology, this refers to an increase in air temperature with altitude. Increasing temperature with altitude is the opposite of the normal temperature condition of the troposphere; usually, temperature decreases with altitude.
Troposphere: The lowest major layer of the atmosphere. The troposphere extends from the Earth’s surface to a height of 6-10 miles (10-16 kilometers) and is characterized by decreasing temperature with increasing altitude. It contains about four-fifths of the mass of the whole atmosphere.
Vessel Traffic Service(VTS): A marine traffic monitoring system created by harbor or port authorities. Typical VTS systems use radar, closed-circuit television, marine VHF radio, and AIS to keep track of vessel movements and provide navigational safety in a specific geographical area.
