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A Radar Display for Collision Avoidance

Published online by Cambridge University Press:  18 January 2010

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In the October issue of the Journal (19, 529), Commander Clissold puts forward a type of radar display which might be useful for collision avoidance, as it intends to show the aspect of the ship representing the danger. To achieve this a long afterglow screen would be used and the display would be oriented head-up, i.e. ship's head at the top of the picture to correspond as closely as possible with a possible visible situation. An electronic cursor, bearing line, would indicate a danger of collision if on constant bearing. This type of display is said to show tracks true relative to own ship's course.

Apart from the fact that 30 seconds afterglow, decaying exponentially as an excited phosphor screen would, might be too short for showing up tracks efficiently, there are some other difficulties as well with such a display. Obviously aspects of target ship would not be shown but implied only by the afterglow track. Furthermore, a display of this kind would be a true-motion type display not necessarily north stabilized but nevertheless showing all motion of other ships in true, if own ship's speed is compensated for in displacing the origin of the radial scan. The difficulty will arise if own ship changes heading and unless this heading change is also compensated for, like in a north-up stabilized true-motion display, smearing of all echoes will occur. A heading change of own ship, therefore, will produce additional apparent tracks of other ships and the apparent displacement of fixed targets.

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Copyright © The Royal Institute of Navigation 1967