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A Morse code light is light in which appearances of light of two clearly different durations (dots and dashes) are grouped to represent a character or characters in the Morse Code. For example, "Mo(A)" is a light in which in each period light is shown for a short period (dot) followed by a long period (dash), the Morse Code for "A".
Watercraft navigation lights must permit other vessels to determine the type and relative angle of a vessel, and thus decide if there is a danger of collision. In general, sailing vessels are required to carry a green light that shines from dead ahead to 2 points (22 + 1 ⁄ 2 °) abaft [note 1] the beam on the starboard side (the right side from the perspective of someone on board facing ...
The International Code of Signals was preceded by a variety of naval signals and private signals, most notably Marryat's Code, the most widely used code flags prior to 1857. What is now the International Code of Signals was drafted in 1855 by the British Board of Trade and published in 1857 as the Commercial Code. It came in two parts: the ...
A sector light is one which shows different colours depending upon the angle of approach. They are commonly used to indicate the safe channel (white) and show red or green if the vessel is out of the safe channel. IALA requires the light colours to follow the appropriate region (A or B) colour scheme. [9]
Day shapes of standard and reduced sizes are both commercially available. Day shapes are commonly constructed from a light weight frame covered with fabric and are designed to be collapsible for ease of storage. A US Navy sailor lowers day shapes "ball, diamond, ball", signaling the end of restricted maneuvering
Leading lights, also known as range lights in the United States, are a pair of light beacons used in navigation [2] to indicate a safe passage for vessels entering a shallow or dangerous channel; they may also be used for position fixing. At night, the lights are a form of leading line that can be used for safe navigation. The beacons consist ...
Some signal lamps are mounted on the mastheads of ships while some small hand-held versions are also used. Other more powerful versions are mounted on pedestals. These larger ones use a carbon arc lamp as their light source, with a diameter of 20 inches (510 mm). These can be used to signal to the horizon, even in conditions of bright sunlight.
A modulation is the form in which the light signal varies in order to represent different symbols. In order for the data to be decoded. Unlike radio transmission, a VLC modulation requires the light signal to be modulated around a positive dc value, responsible for the lighting aspect of the lamp. The modulation will thus be an alternating ...