Installation Of The Scanner Unit; Selecting The Installation Position - JRC JMA-1032 Instruction Manual

Chapter 1 INSTALLATION
1 - 3 IN S T A LL A TI O N O F T H E S C AN N E R U NI T

1-3-1 SELECTING THE INSTALLATION POSITION

■ PHYSICAL SELECTION CRITERIA
■ Install the scanner at the center of the mast on the keel line.
■ If the scanner cannot be installed at the above position for some reason, the amount of deviation
must be minimized. And, reinforce the mount base and the platform and take precautions to
protect the scanner from vibration and impact at the installation position.
■ There needs to be no influence of the dust by smoke from a chimney.
■ Please secure maintenance spaces (a platform, a safety link, a handrail, a step, etc.).
■ ELECTRICAL SELECTION CRITERIA
■ The installation height of the scanner relates to the maximum detection distance.
The higher, the better. However, if it is too high, radio wave energy greatly attenuates
above the scanner's vertical beam width (the point -3 dB from the peak of the main-lobe).
As a result, it is difficult to detect a close-in target. Sea clutter also increases.
Determine the installation height by taking into consideration the weight, maximum
length of the cable, and maintenance after installation. If the installation height of the
scanner is low, it is difficult to detect a long distance target. The ship's mast, derrick,
and chimney interfere with radiating beam causing the range that cannot be viewed
on the radar display to increase.
Generally, the lowest scanner installation position is supposed to be on the A-B line
shown in Fig. 1-3-2. In the case of the JMA-1030 type radar, 2θ equals 25°.
Specifically, the scanner position is normally elevated so that the chimney and the
shrine-gate type mast do not interfere with radiating beam.
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