Italy LRC Marine Radio flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Sea area A1

The sea area within radiotelephone coverage of at least one VHF coast station with continuous DSC alerting, generally about 20 to 30 nautical miles from the coast.

Sea area A3

The sea area within coverage of an Inmarsat geostationary satellite, roughly between 70 degrees north and 70 degrees south, excluding sea areas A1 and A2.

Reserve source of energy

An independent battery supply that feeds the radio installation for at least one hour, or six hours when no emergency generator exists, plus emergency lighting.

Functional requirements

The GMDSS functions: distress alerting, SAR coordination, on-scene communications, locating signals, maritime safety information, general radiocommunications, and bridge-to-bridge communications.

DSC distress alert priority

The distress alert carries the format specifier distress and nature of distress 112, with position, UTC time, and the telecommand indicating the follow-on communication mode.

MAYDAY call content

MAYDAY spoken three times, THIS IS, station identity, MAYDAY and identity again, position, nature of distress, assistance required, persons on board, and other information.

Distress alert repetition rule

A DSC distress alert is repeated only when no acknowledgment arrives, after a random delay of 3.5 to 4.5 minutes, to avoid congestion on the distress frequency.

PAN PAN meaning

The urgency signal used for messages concerning the safety of a ship or person but not immediate danger, such as medical advice or a man overboard situation.

VHF Channel 70

The DSC channel at 156.525 MHz used for digital selective calling on VHF; voice transmissions are prohibited on this channel at all times.

VHF Channel 16

The international distress, safety and calling channel at 156.800 MHz, monitored continuously by ships and coast stations for initial contact and distress traffic.

Bridge-to-bridge channel

VHF Channel 13, used for navigational safety communications between ships and with VTS, normally at reduced power of one watt.

VHF line-of-sight range

Approximate range in nautical miles equals 1.23 times the square root of antenna height in metres, plus the same term for the other station's antenna height.

MF distress frequencies

2182 kHz is used for MF radiotelephony distress and calling, while 2187.5 kHz carries MF digital selective calling distress alerts and watchkeeping.

HF DSC distress frequencies

The five HF DSC distress and safety frequencies are 4207.5, 6312, 8414.5, 12577 and 16804.5 kHz, one in each maritime HF band.

NBDP ARQ mode

Narrow-band direct printing with automatic repetition request, a point-to-point mode where the receiving station requests retransmission of blocks received with errors.

Maximum usable frequency

The highest frequency that the ionosphere refracts back to earth for a given path and time; the optimum working frequency is about 85 percent of it.

NAVTEX 518 kHz

The international NAVTEX frequency carrying maritime safety information in English, with reception range typically 200 to 400 nautical miles from the transmitting station.

SafetyNET

The Inmarsat Enhanced Group Call service that broadcasts maritime safety information to ships in sea area A3, addressed to NAVAREAs or to groups of ships.

SafetyCAST

The Iridium-based maritime safety information broadcast service recognised for GMDSS, giving global coverage that includes the polar sea area A4.

Inmarsat-C distress alert

A distress message sent by pressing the protected distress button, delivering ship identity, position and nature of distress to a land earth station and rescue centre.

406 MHz EPIRB

A float-free beacon that transmits a digital distress message with identity and, when GNSS-equipped, position to the COSPAS-SARSAT satellite system, plus a 121.5 MHz homing signal.

SART radar signature

A search and rescue radar transponder answers X-band radar with twelve pulses, appearing on the radar display as a line of twelve dots radiating from the ship.

SART operating band

The search and rescue radar transponder operates in the 9 GHz X-band, has a range of about 5 to 10 nautical miles, and should be mounted at least one metre above sea level.

EPIRB registration

The beacon must be registered with the national authority, linking its hex identifier to the ship and owner, and the record updated when the flag, name or owner changes.

MMSI structure

A nine-digit Maritime Mobile Service Identity: three-digit MID of the flag state, such as 247 for Italy, followed by the ship station identity digits.

GMDSS operator certificates

The General Operator Certificate covers all sea areas, the Restricted Operator Certificate covers A1, and the Short Range Certificate covers VHF-only installations.

Radio log entries

The station log records distress, urgency and safety traffic, test transmissions, battery checks, and any interference or equipment failure, kept available for inspection.

VSWR limit

The voltage standing wave ratio of an antenna system should stay below about 2 to 1; a higher value indicates a feeder or antenna fault that can damage the transmitter.

Battery specific gravity

A fully charged vented lead-acid cell shows a specific gravity near 1.265; a lower reading indicates discharge, and the electrolyte level must cover the plates.

Ionospheric D layer

The lowest ionospheric layer, present mainly by day, which absorbs MF and lower HF signals and so reduces daytime skywave propagation on those bands.

False EPIRB alert action

Switch the beacon off immediately, then notify the rescue coordination centre or coast station by radio so the search and rescue response can be cancelled.

RF exposure precaution

Personnel should stay outside the near field of transmitting antennas, keeping at least one to two metres from HF antennas to avoid radio frequency burns.