Garmin Flight Deck 100 Marine Instruments User Manual


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Embraer Prodigy
®
Flight Deck 100 Pilot’s Guide
190-00728-04 Rev. A
360
HAZARD AVOIDANCE
Figure 6-52 Precipitation Type and Reflectivity
groUnD retUrns
The intensity of ground target returns depends upon theangle at which the radar beam strikes the
groundtarget(AngleofIncidence)andthereectivepropertiesofthattarget.Thegaincanbeadjustedso
shorelines,rivers,lakes,andcitiesarewelldened.Increasingthegaintoomuchcausesthedisplaytoll
in between targets, thus obscuring some landmarks.
Citiesnormallyprovideastrongreturnsignal.Whilelargebuildingsandstructuresprovidegoodreturns,
smallbuildingscanbeshadowedfromtheradarbeambythetallerbuildings.Astheaircraftapproaches
and shorter ranges are selected, details become more noticeable as the highly reflective regular lines and
edges of the city become more defined.
Bodiesofwatersuchaslakes,rivers,andoceansarenotgoodreectorsandnormallydonotprovide
goodreturns.Theenergyisreectedinaforwardscatteranglewithinadequateenergybeingreturned.
Theycanappearasdarkareasonthedisplay.However,roughorchoppywaterisabetterreectorand
provides stronger returns from the downwind sides of the waves.
Mountainsalsoprovidestrongreturnsignalstotheantenna,butalsoblocktheareasbehind.However,
over mountainous terrain, the radar beam can be reflected back and forth in the mountain passes or off
canyonwalls,usingupallormostoftheradarenergy.Inthiscase,noreturnsignalisreceivedfromthis
area,causingthedisplaytoshowadarkspotwhichcouldindicateapasswherenopassexists.
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