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7.11
GNSS
The EPIRB has a built in GNSS receiver capable of receiving signals from
GPS, GLONASS and Galileo GNSS satellite systems. The position fix is
normally accurate to a few meters and is encoded by the message
generator of the EPIRB and transmitted to the Cospas-Sarsat satellites. The
resolution of the transferred fix is somewhat limited compared to the
original GNSS fix. The uncertainty is about 500m. The GNSS position fix and
the position calculated by the Cospas-Sarsat system itself will together give
a precise indication of the actual position.
When it comes to AIS homing the position format will reflect the GNSS
position fix without any performance degradation. The accuracy will
typically be approximately 2.5m. The position fix is updated each 5 minutes
for both Cospas-Sarsat messages and AIS messages and reflected in the
next transmission.
7.12
RLS system
This beacon has the Return Link Service (RLS) feature. The RLS feature is
an indication on the beacon (see beacon user’s manual) that confirms to
the beacon user that the distress signal from an activated beacon has
been localised by the Cospas-Sarsat system and is being sent to the
responsible search-and-rescue (SAR) authorities. It does NOT mean that
a search and rescue has yet been organized/launched, only the fact that
the distress alert has been received and is being routed to the
appropriate SAR agencies.
The RLS is designed to send an acknowledgment to the EPIRB user in less
than 30 minutes from beacon activation. Because this RLS performance still
is under development, prior to around 2021 the acknowledgment to the
beacon user may take somewhat longer than 30 minutes in certain parts of
the world. Alerting of the distress to SAR authorities is independent of (and
likely will occur before) the RLS acknowledgment indication on the beacon.
This specification is described in the Galileo SAR Service Definition
Document:
(https://www.gsceuropa.eu/sites/default/files/sites/all/files/Galileo-SAR-
SDD.pdf).