5.2.6 Detection range
With its wide field of view, night vision equipment should detect a target with a height of 1.5 m and a width of 1 m from a distance of at least 600 m with a minimum probability of 90% (equivalent to 1.7 line pairs per target dimensions) at a standard visibility of 1,000 m and display it on a monitor under the following conditions, as applicable：
- a maximum contrast of 0.25 (in the visual and near infrared range) between the target and its surroundings;
- a maximum ambient illumination E of 10-4 Lux;
- a maximum temperature difference T of 1 K between the target and its surroundings.
The surroundings of objects commonly encountered at sea and in ports should not be displayed less clearly on the monitor of the night vision equipment because of dazzle effects, reflection, blooming, or any other effects.
5.3 MALFUNCTIONS, WARNINGS, ALARMS, AND INDICATIONS
Night vision equipment should have the following displays
- state of operation;
- visual alarm in the event of failure of the night vision equipment;
- operating hours counter.
5.4 SOFTWAKE REQUIREMENTS
If certain functions of night vision equipment are implemented using software, such software should meet the applicable requirements of international Organizations *. The software should meet the following requirements in particular：
- clear delimitation of open and closed systems;
- correctness and stability of the software;
- capability of system re-start after brief power failure;
- clear identifiability of the software used, and updating capability;
- availability of required software test procedures;
- possibilities of failure detection and troubleshooting;
- activation of alarm in the event of software malfunctions.
* IgO/IEC 9126
