Appendix IXIX Frequencies for use in the GMDSS
ALL ITEMS OF GMDSS RADIO/SATCOM EQUIPMENT use specific frequencies/
channels for particular purposes. Some equipment (Inmarsat systems
and EPIRBs) may not have facilities for user-selected frequencies/
channels.
NAVTEX receivers may have a single fIxed frequency; be dual-
frequency (user selectable); or may have a facility for user-selection of
an external receiver.
7.3 Marine MF /HF SSB radio - schematic diagram
the user to select channels/frequencies for the job at hand.
The following tables explain the main frequency bands, channels
and frequencies used by or available on each type of equipment.
Inmarsat Ship Earth Stations (SES - including the Inmarsat-E EPIRB)
All use frequencies at 1·6GHz (L-Band). The Inmarsat EPIRB will,
additionally, use 121·SMHz for 'local homing' by SAR craft.
Cospas-Sarsat EPIRB
Uses 406MHz for position-fixing through the satellite and
121·SMHz for 'local homing' by SAR craft.
NAVTEX
The primary frequency for English language broadcasts,
worldwide, is 518kHz. Some countries also use 518kHz for additional,
local language, broadcasts. Local area/language broadcasts may also be
transmitted on 490kHz. The frequency 4209 ·5kHz is provided,
additionally, for NAVTEX broadcasts in the 'tropical zone' - where MF
broadcasts are subject to greater levels of 'static' than at higher latitudes.
Marine VHF radio - key channels
Ch70 DSC alerts/calls (Distress, Urgency, Safety and Routine).
Ch16 For voice Distress, Urgency and Safety Messages and for Routine
voice calls.
Ch 13 The voice 'Intership Safety of Navigation Channel' - for bridge-
to-bridge communications between ships. May be allocated locally
to port/harbour services or to locks/bridges, in which case you
must be careful to avoid interference to those services.
Ch06 The primary intership channel. One of a number of channels
available for intership working. Used also for communication
MARINE COMMUNICATIONS 235