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across the complete radar frequency band (9200 – 9500 MHz). At some point in each
sweep, the SART frequency will match that of the interrogating radar and be within the
pass-band of the radar receiver. If the SART is within range, the frequency match will
produce a response on the radar display (typically a line of 12 dots or arcs equally spaced
by about 0.64 nautical miles out from the SART’s location).
4.3.2.2 Operational Requirements
SARTs form part of the GMDSS (which applies to cargo ships of 300 gross tons and over
when travelling on international voyages or in the open sea and all passenger ships
carrying more than twelve passengers when travelling on international voyages or in the
open sea), and SARTs are mandatory in any of the GMDSS sea areas.
4.3.2.3 Regulatory and Standardisation Issues
SARTs are standardised by the IEC in document IEC 61097-1 (Global maritime distress
and safety system (GMDSS) – Part 1: Radar transponder – Marine search and rescue
(SART) – Operational and performance requirements, methods of testing and required
test results). ETSI standard ETS 300-151 (Radio Equipment and Systems (RES); 9 GHz
radar transponders for use in search and rescue operations Technical characteristics and
methods of measurement) also applied but has since been withdrawn.
Socio-economic factors
9 GHz SARTs are mandated by GMDSS. Unless there is a change in the requirement, it
is highly unlikely that the UK could take a unilateral decision to modify the specification or
otherwise employ alternative technologies. SARTs form part of the key safety-of-life backstop
for vessels in distress.
4.3.2.4 Possible Improvements to existing technology
There are no developments planned to the existing SART specifications.
4.3.2.5 Possible New Technologies (in-band)
No new technologies have been identified.
4.3.2.6 Alternative Technologies or Spectrum (other or none)
No alternative technologies have been identified.
4.3.2.7 Allocation Sharing Opportunities
No sharing opportunities specific to SARTs have been identified.
4.3.2.8 Possible Overall Spectrum Efficiency Improvements
It is worth noting that any move to reduce the amount of spectrum available to maritime
radars in the 9 GHz band for re-use by other services could be hampered by the
presence of SARTs. The SART response to interrogation, i.e. to emit a signal that sweeps
across the whole radar band (thereby ensuring that it is detected by the interrogating
radar – and any others nearby) means that if the allocation to maritime radar in the 9 GHz
band were to be reduced, any existing SARTs, when triggered would emit a signal across
the whole of the current band, ignoring the reduction in allocation.
That being said, SART usage is for emergencies only, and hence the level of interference
caused by the SART would be very limited. They are also most often used at sea, further
reducing the potential for interference into the UK. As the SART would still be sweeping
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