Raymarine RL80C Plus Specifications Page 74

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3-6 hsb
2
PLUS Series Color LCD Display
Identifying False Echo
Returns
Indirect Echoes
Thereareseveraltypesofindirectechoesorghostimages-someexamplesare
showninFigure 3-4.Thesesometimeshavetheappearanceoftrueechoes,
butingeneraltheyare intermittentand poorlydefined.
Figure 3-4: Indirect Echoes
Multiple Echoes
Multiple echoes appearif there is a largetarget with a wide verticalsurfaceat
acomparatively shortrange.Thetransmittedsignal willbereflectedbackand
forthbetweenthetargetand your own ship. Multipleechoesthereforeappear
beyondthe truetarget’sechoonthesame bearing,as shown in Figure 3-5.
Thisis not very common.
Figure 3-5: Multiple Echoes
Blind Sectors or Shadow Effect
Funnelsand mastslocatedneartheantenna,may causeshadows. Inshadow
areasbeyondtheobstruction there willbe areduction ofthebeam intensity,
althoughnotnecessarily a completecut-off. However, there willbeablind
sectorifthesubtendedangleis more thana few degrees.There mayalsobe
multipleechoeswhichextendbehindtheobstruction.Thisshouldbeavoided
bycarefulselectionofthescannersiteprior to installation (Chapter 8).
False echo
True echo
Passing
ship
True echo
False echo
D1641-2
Mast
or funnel
Indirect (false) echoes
D1642-1
True echo
Multiple echoes
MULTIPLE ECHOES
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