User's Manual Part 2

Operator Manual
Raytheon Marine GmbH
Germany
R
NSC 18
RADAR
3−5
3748DOC020102Edition: 14.JAN.2005
3.2 Radar Pattern Interpretation
The radar displays a chart−like picture (PPI) on TFT under normal conditions.
Under certain conditions, however, various false echoes are generated, and
small targets are hidden by rain, snow or sea waves. To correctly interpret tar-
gets and patterns which appears on the TFT requires considerable experience.
Compare patterns that appear on the radar image to the actual topography to
acquire experience as far as possible.
3.2.1 Range
The detectable range depends on the antenna height and height of targets.
Sometimes, however, the radar detectable range is longer due to refraction of
the wave beam according to weather conditions.
The radio wave is obstructed by mountains and hills, forming a shadow behind
these objects.
D = 2 (√ H1 + √ H2)
H
1
H
2
D
Figure: 3−2 Detectable Range
D[NM]
H[m]
Examples:
A big ship with 25 m antenna high can detect a 4 m high small ship in up to
14 NM distance.
A big ship with 25 m antenna high can detect a 25 m high ship in up to 20 NM.
A big ship with 25 m antenna height can detect a 100 m high coast in up to 30
NM.