Raymarine A series - Page 318

Interference
Whentwoormoreradar-equippedvesselsare
operatingwithinrangeofeachothermutualradar
interferencecanoccur.Thisusuallyappearsasa
spiralofsmalldotsfromthedisplaycentreThistype
ofinterferenceismostnoticeableatlongranges.
Thisinterferencecanbesuppressedusingthe
interferencerejectionsettings.Theimagesinthe
tablebelowshowhowtheInterferencerejection
settingscanclearupsomeofthisinterference:
Interfer-
encere-
jection
off
Interfer-
encere-
jection
on
Maximumradarrange
Theusablerangeoftheradarislimitedbyfactors
suchastheheightofthescanner,andheightofthe
target.
Maximumradarrangeisessentiallyline-of-sight,so
islimitedbytheheightofthescannerandtheheight
ofthetargetasillustratedbelow:
a
1
a
2
h
H
D1643-4
R
max
R
max
= 2.23 ( h + H )
1
3
2
ItemDescription
1Radarequippedvessel.
2
Curvatureoftheearth.
3
Target(Cliff).
a
1
Radarhorizonofantenna.
a
2
Radarhorizonoftarget.
R
max
Maximumradarrangein
nauticalmiles.
R
max
=a
1
+a
2
hRadarantennaheightin
metres.
HTargetheightinmetres.
Thetablebelowshowstypicalmaximumradar
rangesforvariousradarantennaheightsandtarget
heights.Rememberthatalthoughtheradarhorizon
isgreaterthantheopticalhorizon,theradarcanonly
detecttargetsifalargeenoughtargetisabovethe
radarhorizon.
Antennaheight
(meters)
Targetheight
(meters)
Maximumrange
(Nauticalmiles)
33
7.7
31010.9
5
38.8
5
1012
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