Raymarine e95 - Radar Range and Image Quality

2.SelectPowerupRadartoturntheradaron,orPowerdown
Radartoturntheradaroff.
3.SelectRadar:Txtostarttheradartransmitting,orRadar:
Stdbytostoptheradartransmitting.
16.4Radarrangeandimagequality
Maximumradarrange
Theusablerangeoftheradarislimitedbyfactorssuchasthe
heightofthescanner,andheightofthetarget.
Maximumradarrangeisessentiallyline-of-sight,soislimited
bytheheightofthescannerandtheheightofthetargetas
illustratedbelow:
a
1
a
2
h
H
D16 43-4
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
Maximumradarrangeinnautical
miles.
R
max
=a
1
+a
2
hRadarantennaheightinmetres.
HTargetheightinmetres.
Thetablebelowshowstypicalmaximumradarrangesforvarious
radarantennaheightsandtargetheights.Rememberthat
althoughtheradarhorizonisgreaterthantheopticalhorizon,the
radarcanonlydetecttargetsifalargeenoughtargetisabove
theradarhorizon.
Antennaheight
(meters)
Targetheight
(meters)
Maximumrange
(Nauticalmiles)
33
7.7
31010.9
5
38.8
5
1012
Radarimagequality
Anumberoffactorscanaffectthequalityofaradarimage,
includingechoes,seaclutter,andotherinterference.
Notallradarechoesareproducedbyvalidtargets.Spuriousor
missingechoesmaybecausedby:
•Sidelobes.
•Indirectechoes.
•Multipleechoes.
•Blindsectors.
•Sea,rain,orsnowclutter.
•Interference.
Throughobservation,practice,andexperience,youcan
generallydetecttheseconditionsveryquicklyandusetheradar
controlstominimizethem.
SideLobes
Sidelobepatternsareproducedbysmallamountsofenergy
fromthetransmittedpulsesthatareradiatedoutsidethenarrow
mainbeam.Theeffectsofsidelobesaremostnoticeablewith
targetsatshortranges(normallybelow3nm),andinparticular
withlargerobjects.Sidelobeechoesformeitherarcsonthe
radarscreensimilartorangerings,oraseriesofechoesforming
abrokenarc.
162NewaSeries/NewcSeries/NeweSeries