Interference Rejector; Echo Stretch - Furuno FAR-1513 Operator's Manual

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Interference Rejector

Mutual radar interference can occur in the vicinity of another shipborne radar operat-
ing 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 ex-
tending 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 rejec-
tion depending on the number of transmissions that are correlated.
To adjust the interference rejector, select the [IR] box at the left side of the screen,
then press the left button to cycle through the rejection levels. The available settings,
in cyclic order, are: [OFF]  [1]  [2]  [3]  [OFF]...
Level [3] provides the highest level of rejection.
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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, select the [ES] box at the left side of the screen, then press the
left button to cycle through the settings.
The cyclic order is [OFF]  [1]  [2]  [3]  [OFF]...
Example of interference
1. OPERATIONAL OVERVIEW
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