Furuno FAR-2107(-BB) - Manual (Page 65)

1. RADAR OPERATION
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1.25 Interference Rejector
Mutual radar interference may occur in the vicinity of another shipborne radar
operating in the same frequency band. It is seen on the screen as a number of
bright spikes either in irregular patterns or in the form of usually curved
spoke-like dotted lines extending from the center to the edge of the picture.
Activating the interference rejector circuit can reduce this type of interference.
The interference rejector is a kind of signal correlation circuit. It compares the
received signals over successive transmissions and reduces randomly occurring
signals. There are three levels of interference rejection depending on the
number of transmissions that are correlated.
Interference
To adjust the interference rejector, left-click IR indication at the left side of the
screen to select rejection level. "3" provides the highest degree of reduction.
Note: The interference rejector can also be adjusted from the PICTURE box.
1.26 Echo Stretch
The echo stretch feature enlarges targets in the range and bearing directions to
make them easier to see, and it is available on any range. There are three types
of echo stretch, 1, 2 and 3, and the higher the number the greater the amount of
stretch.
Note: The echo stretch magnifies not only small target pips but also returns
(clutter) from sea surface, rain and radar interference. For this reason,
make sure these types of interference have been sufficiently reduced
before activating the echo stretch.
To set echo stretch, left-click the ES indication at the left side of the display.
Note: Echo stretch can also be adjusted from the PICTURE box.