Sensitivity
The ability of a radio receiver to capture weak signals and amplify them
to a useful level.
SES
Inmarsat Ship Earth Station (the satcom transceiver onboard a ship).
Sky Wave
Method of radio wave propagation used at High Frequency.
SOLAS
Refers to the 'International Convention for the Safety of Life at Sea',
which includes requirements for certain classes of ships, when at sea, to
be able to communicate effectively in a variety of situations including:
sending and receiving Distress Alerts; receiving Maritime Safety
Information; and exchanging day-to-day communications with other
vessels and with Coast Stations.
Ship Station
The radio installation onboard a seagoing vessel (leisure or commercial).SRR
Search and Rescue Region (a sea area of responsibility for a particular
state or administration).
SSB
Single Sideband - a method of radio transmission, which is economical
in the use of the radio spectrum (see also LSB/USB)
Tropical Zone
That area either side of the equator where ionospheric energy is at
maximum due to the sun being virtually directly overhead - and where
MF reception is affected by static much more than at higher latitudes.
Urgency
An 'urgency' situation is where a vessel is in need of urgent assistance to
ensure the safety of the vessel, or a person.
USB
The Upper Sideband of a radio signal (see also LSB/SSB)
VHF
Very High Frequency
VTS
Vessel Traffic Service (or Ship Movement Service) - radio traffic within
managed seaways (see also Port Operations).216 THE NAUTICAL INSTITUTE