Strength Of Reflection From The Targets; Sea Clutters; False Echoes - JRC JMA-9832-SA Instruction Manual

......Strength of Reflection from the Targets ..............................

The signal intensity reflected from a target depends not only on the height and size of the target but also
on its material and shape. The echo intensity from a higher and larger target is not always higher in
general.
In particular, the echo from a coast line is affected by the geographic conditions of the coast.
If the coast has a very gentle slop, the echo from a mountain on the inland appears on the radar display.
Therefore, the distance to the coast line should be measured carefully.

......Sea Clutters .....................................................................

When the sea surface ruffles, bright echo returns spread around the center of the radar display.
The higher the waves are, the echo returns are larger.
Swirling currents may appear as a smooth line like a coastal line.

......False Echoes ..................................................................

The radar observer may be embarrassed with some echoes that do not exist actually. These false echoes
appear by the following causes that are well known:
[ ] Shadow
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When the radar scanner is installed near a funnel or mast, the echo of a target that exists in the direction
of the funnel or mast cannot appear on the radar display because the radar beam is reflected on the
funnel or mast. Whether there are some false echoes due to shadows can be checked by monitoring the
sea clutter returns, in which there may be a part of weak or no returns.
Such shadows appear always in the same directions, which the operator should have in mind in radar
operation.
Fig.6.2
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