American Boat & Yacht Council is a not-for-profit organization that develops safety standards for boat building and repair.

Alternating Current - An electrical current that reverses directional regular intervals. In the United States the standard reversal rate is 60 times per second. In many other countries the standard is 50 times per second.

Automatic Identification System. A system used in Commercial Shipping. It allows another station to interrogate the vessel radio to learn the ship's position, course, speed, vessel type, cargo, etc.

Short for Ampere. The unit of measurement for electric current.

A meter connected in series with a circuit and measures the current flowing through the circuit.

A measure of the electrical capacity of a battery. For example, a new fully charged 225 amp-hour battery can theoretically deliver 1 amp for 225 hours.

The positive terminal of a battery or cell.

American Wire Gauge. A measurement of the size of a conducting wire and thus its current carrying capability. In this system, the smaller the AWG number is the larger the diameter of the wire.

The electrical connection of metallic components of the vessel to the ground (-) side of the DC system. (I.e. negative terminal of the 12 volt battery system.)

A unique sequence of letters and numbers issued by the FCC to a vessel that is required to carry radio equipment. Example: WCT2586. Used as an identifier instead of the vessel's name when using radio communications. Also available to recreational vessels that normally do not require radio equipment (but have it) for use in foreign ports.

A group of specifications that includes intended use, transmit frequency, receive frequency, modulation type, and sometime power setting defined by the ITU for maritime communications.

Short for Coaxial. The type of cable used to connect the output of the radio to the antenna. COAX is constructed with two concentric conductors. A stranded or solid center conductor surrounded by a braided outside conductor or 'shield'. COAX is manufactured in many types and sizes. It is very important to match the COAX to the type of radio utilized. For instance the type of COAX used for television is not suitable for used with a marine VHF radio.

The discharge current rating of a battery at a temperature of zero degrees Fahrenheit that it can deliver for 30 seconds and maintain a voltage of 1.2 volts per cell or higher.

A satellite based search and rescue system designed to locate EPIRBs transmitting on 121.5 and 406 MHz.

Coast Radio Station. A land-based service that provides ship-to-shore communications between the vessel's radio and regular telephone lines.

Decibel. A term used to describe effective signal strength gain or loss. dB gain is usually associated with antennas. dB loss is usually associated with coaxial transmission cable and with the ability of a receiver to reject unwanted signals near your operating frequency. A gain (or loss) of 3 dB indicates an effective doubling (or halving) of signal strength.

Digital Selective Calling. A feature of all new radio designs that provides the capability to transmit a digital signal to other radio stations) with the DSC capability.

Dual-Tone Multi-Frequency signaling. A direct-dial feature that allows direct connection to the regular telephone system ashore.

A feature that allow a marine VHF radio to monitor channel 16 and one other channel at the same time.

A radio communication that uses two different frequencies. One for transmit, another to receive. Conversations using Duplex technology can be held as if they were using a normal telephone system. Requires a duplex capable radio and two antennas.

Emergency Position-Indicating Radio Beacon. An emergency transmitting device used to signal a dire emergency and assist in finding your location.

Federal Communications Commission. The United States federal department that regulates frequency allocations, licensing, usage rules, etc. for all radios and transmitting devices used in the United States.

The characteristic of an antenna to focus the signal output of a radio to effectively increase that power in a specific angle of radiation.

Global Maritime Distress and Safety System. A worldwide system for dealing with distress situations at sea.

Global Positioning System. A satellite based system that provides and land or sea based GPS receiver with an accurate position.

A radio communication that uses two different frequencies on one channel and switches back and forth for transmit and receive. Only one party can talk at a time. Mostly used on coast station channels for making phone calls.

High Frequency. A loose definition of a band of frequencies that range from 3 MHz to 30 MHz. Most marine SSB channels reside in this range of frequencies.

A measure of power. One horsepower equals 746 watts.

Hertz. The unit of Frequency. One Hertz equals one complete cycle occurring in one second.

Impedance is the measurement of the attenuation of a radio signal within a conductor or COAX.

A company that operates a constellation of geostationary satellites that extend mobile phone, fax and data communications to every part of the world, except the poles.

International Telecommunications Union. The governing body for worldwide telecommunications.

Kilohertz. One Kilohertz equals 1,000 Hertz. See Hertz.

A license issued by the FCC to allow operation of a marine VHF radio from land.

A private marine telephone business that provides ship-to-shore telephone and data services.

Used at the start of an emergency broadcast concerning grave and imminent danger to a vessel and/or people.

Medium Frequency. A loose definition of a band of frequencies that range from 1,600 to 4,000 KHz.

Megahertz. One Megahertz equals 1,000,000 Hertz. See Hertz.

Maritime Mobile Service Identity. A unique number assigned to a vessel. The complete number consists of a nationality code (MID) and an individual station identity. The MMSI is broadcast digitally at the beginning of any DSC contact.

A worldwide coastal system that broadcasts maritime safety information in text form to vessels up to 300 miles offshore. Operates on 518 kHz and requires special equipment.

National Marine Electronics Association. Defines certain standards for marine electronic equipment such as the NMEA serial interface used to allow a GPS to communicate with an Autopilot.

A fast and reliable ARQ teletype mode, developed to overcome the shortcomings of AMTOR and Packet Radio on short wave.

Used at the start of an urgent radio broadcast to concerning the safety of a vessel and/or people.

The connector type utilized to connect the antenna to the radio. Various types of PL 259 connectors are available to fit different sizes of COAX. PL 259 connectors come in solderable and 'quick connect' types. The solderable type connector is highly from a long term reliability stand point.

Sometimes called 'Tag Scan'. A feature that allows the radio to scan user selected channels. Channel 16 is usually automatically included in this mode.

The number of minutes a new fully charged battery at a temperature of 80 degrees Fahrenheit can be discharged at 25 amps and maintain a voltage of 10.5 volts or higher for a 12 volt battery.

An abbreviation for "Receive." Often displayed on the display of a radio to indicate that the radio is in the receive mode of operation.

Specific Area Message Encoding. A tone system that allows SAME equipped radios to sound an alert for specific types of weather conditions or an alert for broadcasts in a specific limited geographical area.

Used at the start of a radio broadcast concerning a hazard to navigation or ship movements.

A value which describes the radios ability to reject signals which are near the frequency you are working on so as to not let them interfere with your communications. This is a more important factor when choosing a radio than 'Sensitivity'.

A value which describes the radios ability to receive a signal. It is expressed in micro-volts (example: a typical value could be 0.25 uV. Most radios are produced with more than adequate sensitivity.

License issued by the FCC to operate marine radio equipment aboard a vessel. Recreational vessels operating in U.S. waters are no longer required to have a Ship Station License

A radio communication that uses the same frequency for both transmit and receive. Only one person can talk at a time when using simplex channels. Any station can listen to both sides of the conversation.

Safety Of Life At Sea. An international convention addressing the safety of life at sea. Defines many of the regulations governing the safety of vessels.

A radio control that suppresses unwanted background noise while monitoring for radio traffic.

Terminal Node Controller. A device that is installed between a computer and an SSB radio that provides data transmission to and from other PACTOR stations via the internet.

An abbreviation for "Transmit." Often displayed on the display of a radio to indicate that the radio is in the transmit mode of operation.

Universal Coordinated Time. The basis for all time calculations based on the time at the 000 degree meridian which passes through Greenwich, England. (Previously known as Greenwich Mean Time or GMT.)

Very High Frequency. A loose definition of a band of frequencies that range from 30 to 300 MHz. The marine segment of the VHF band is from 156 MHz to 162 MHz.

The unit of electrical power. One Watt is equivalent to 0.00134 Horsepower.