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IMCA M 229
11
Operational Experience
11.1
Co-location/Sensor Placement
The sensor operates in a narrow frequency band between 9.2 GHz and 9.3 GHz, which is part of the
X-band frequency spectrum. This licence-free spectrum is shared with other marine systems such as
marine navigation radars or Artemis. The high transmit power (typically kW) usually associated with
X-band radars means that it is important for the Mini RadaScan sensor to be located in a position or
shielded so that other radar signals cannot interfere with it.
Figure 14 – Mini RadaScan co-location
The sensor design includes interference protection, which prevents any damage to the sensitive
electronics. However it is possible to encounter a loss of performance, which can be mitigated by
positioning the sensor and the interfering system on different horizontal planes (Figure 14) with as much
vertical separation as possible between the Mini RadaScan Sensor and any X-band radar.
If vertical separation of the two systems is impossible, they must be shielded from one another with a
metal screen. The screen must be large enough to physically shield the Mini RadaScan sensor from the
whole width of the X-band antenna.
The Mini RadaScan sensor does not need to be shielded from radar-based systems mounted on other
vessels or structures.
11.2
Performance
The performance of any measurement system can be characterised in terms of accuracy, availability,
continuity and integrity.
In the case of a local position reference sensor, availability, continuity and integrity depend on local
operational factors, e.g. how well maintained are the reflectors? What obstructs the view from sensor
to reflector? These statistics vary factors widely across all installations.
For dynamic positioning accuracy a relatively small constant offset error in a local position reference is
of little concern. For station keeping performance we require:
local accuracy – once the vessel is in position and holding station, the measurement of displacement
within a small area is accurate;
repeatability – if the vessel returns to the same actual position, the same position is reported as
before.
The measure of accuracy is determined for the Mini RadaScan by the error model.
Summary of Contents for Mini RadaScan
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