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Bearing resolution
Bearing resolution is the ability of the radar to display as separate pips the echoes received from
two targets which are at the same range and close together. It is proportional to the scanner length
and reciprocally proportional to the wavelength. The length of the scanner radiator should be
chosen for a bearing resolution better than 2.5° (IMO Resolution). This condition is normally
satisfied with a radiator of 1.2 m (4 ft) or longer in the X-band. The S-band radar requires a radiator
of nominal 12 feet (3.6 m) in our product range.
Range resolution
Range resolution is the ability to display as separate pips the echoes received from two targets
which are on the same bearing and close to each other. This is determined by pulselength only.
Practically, a 0.08 microsecond pulse offers the discrimination better than 35 m as do so with all
FURUNO radars.
Test targets for determining the range and bearing resolution are radar reflectors having an echoing
area of 10 m
2
.
Bearing accuracy
One of the most important features of the radar is how accurately the bearing of a target can be
measured. The accuracy of bearing measurement basically depends on the narrowness of the
radar beam. However, the bearing is usually taken relative to the ship’s heading, and thus, proper
adjustment of the heading line at installation is an important factor in ensuring bearing accuracy. To
minimize error when measuring the bearing of a target, put the target echo at the extreme position
on the screen by selecting a suitable range.
Range measurement
Measurement of the range to a target is also a very important function of the radar. Generally, there
are two means of measuring range: the fixed range rings and the variable range marker (VRM). The
fixed range rings appear on the screen with a predetermined interval and provide a rough estimate
of the range to a target. The variable range marker’s diameter is increased or decreased so that the
marker touches the inner edge of the target, allowing the operator to obtain more accurate range
measurements.