Raymarine C90w, C140w manual Radar display overview, Interference

Interference

When two or more radar-equipped vessels are operating within range of each other mutual radar interference can occur. This usually appears as a spiral of small dots from the display centre This type of interference is most noticeable at long ranges.

9.4 Radar display overview

With your radar scanner connected and the radar in transmit mode, the radar picture provides a map-like representation of the area in which the radar is operating.

Typically, your boat’s position is at the centre of the display, and its dead ahead bearing is indicated by a vertical heading line, known as the Ship’s Heading Marker (SHM).

On-screen targets may be large, small, bright or faint, dependent on the size of the object, its orientation and surface. If using an analog radar scanner, strongest target returns are displayed in yellow with weaker returns in two shades of blue. If using a digital radar scanner, stronger target returns show as different colors from a range of 256 colors, providing better clarity. Be aware that the size of a target on screen is dependent on many factors and may not necessarily be proportional to its physical size. Nearby objects may appear to be the same size as a distant larger objects.

104 C-Series Widescreen user reference