About VHF-Marine-RadioABOUT VHF-MARINE-RADIO The VHF radio spectrum consists of 55 channels in the 156.50 to 163.275 MHz band. As VHF radio is line of sight the higher the two antennas are mounted, the greater the distance. There are theoretical ways to work out the range but for simplicity I will leave them out. Factors such as atmospheric conditions and the installation itself such as aerial type and placement also affect the actual range. ABOUT VHF RADIO LICENSING All countries have licensing regulations that must be adhered to. Failure to comply may result in prosecution and fines. Ship Station License. All VHF installations must possess a station license issued by the appropriate national communications authority, i.e. FCC. On issue of the first license a call sign is issued. Operator License At least one operator, normally the person registering the installation should possess an operator's license or certificate. Under GMDSS and DSC this has changed, in the UK it is the Short Range Certificate (SRC), similarly they have changed in the USA, Canada and Australia. It requires a short one-day course. ABOUT VHF-MARINE-RADIO SIGNAL PROPAGATION VHF signals penetrate the ionosphere rather than reflect. There are circumstances in which VHF signals can reflect back from the ionosphere to give “freak” long distance communications such as during very strong solar cycles. This occurred during cycle 19 in 1957/58, cycle 21 in 1980 and cycle 22 in 1990. During these peaks, the monthly sunspot average rose to extremely high values and the ionosphere reflected higher frequencies than normal. VHF can also be reflected from clouds of increased ionization in the E layer of the ionosphere, and during auroras, which are the light curtains caused by charged particles from the sun
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