User's Manual
Table Of Contents
14
5
BASICRADARTHEORY
■BlindandShadowsectors
Blind or Shadow sectors may exist because of
obstructions such as masts, derricks or stacks. An
obstruction may throw either a complete or partial
shadow as shown in the diagram below. If a target is
in a shadow sector, target echoes may not appear on
the screen.
When tall and massive targets such as a large island
are located at close range also shadowed without
producing any echoes. This phenomenon is called
blind sector. It is very important to know the bearings
and widths of all shadow sectors caused by your own
ship’s obstructions.
■Targetresolution
Target resolution is determined by the horizontal
beam width and transmit pulse width. Sometimes it is
difficult to detect two targets which are separated by
short distances or which are in the same direction.
DDistanceresolution
When two targets are separated by more than the
pulse width, they appear as two echoes.
When two targets are not separated by more than
the pulse width, they appear as 1 echo.
Transmit
pulse
Echoes
Target 1
Target 2
Target 2
Target 1
DDirectionresolution
When two targets are separated by more than the
horizontal beam width, they appear as two echoes.
When two targets are not separated by more than
the horizontal beam width, they appear as one
echo.
Scanner
Target 2
Target 1
Target 1, 2
Mast or
similar
obstruction
Shadow sector
Blind sector
Own ship
Large
island
Small
island
Target 2
Target 1
Scanner
Target 2
Target 1
Transmit
pulse
Echo
Target 1,2
Target 1, 2
MXR-5000T / Page 13-2-16