5 FUNCTIONAL REQUIREMENTS
5.1 REQUIRED FUNCTIONS AND THEIR AVAILABILITY
At night, night vision equipment should be capable of detecting objects above the water surface within a certain distance from one's own craft, and of displaying the information pictorially in real time, to assist in collision avoidance and safe navigation.
5.2 RELIABILITY, ACCURACY AND DISCRIMINATION
5.2.1 Continuous operation
Night vision equipment on board HSC, while navigating at sea, should be capable of continuous operation from after sunset until before sunrise. After the equipment has been switched on it should be operational in less than 15 min.
5.2.2 Standard test target
The standard test target should be a black metal target of such a size that when at least 50% is immersed, 1.5 m long x 0.5 m high remains above the water at right angles to the desired direction of detection. Administrations may use other smaller targets to reflect local conditions.
5.2.3 Detection range
With the required field of view, the equipment should detect the standard test target at a distance of not less than 600 m with a minimum probability of 90%, when the target has been immersed in the sea for at least 24 hours under mean starlight conditions without clouds and without moon.
5.2.4 Field of view
The required horizontal field of view should be at least 20°, 10° on either side of the bow. The vertical field of view should be at least 12°and should be sufficient to enable the equipment to fulfil the performance requirements of this standard as well as being able to see the horizon.
Optionally other fields of view may be provided. Their selection should be made with a non locking switch, which returns to the required field of view when released.
5.2.5 Pan and tilt ranges of the fields of view
The axis of the field of view of the equipment should be capable of being moved at least 20° horizontally to either side.
The elevation axis of the field of view should be capable of being adjusted by at least 10｡?o compensate for the trim of the craft.
5.2.6 Speeds of panning of the fields of view
By activation of a single control element, the axis of the field of view should be capable of being returned automatically to the ahead position at a minimum angular speed of 30°/s. The system should be capable of panning at a minimum angular speed of 30°/s
