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Navigational Radar, Continued
Figure 8-31. PPI presentation.
PPI Display
Interpretation
The scope can be adjusted to several different range scales to provide
greater target detail. Range is measured in yards or nautical miles from
the center of the scope to the target indicated.
Some factors affecting the accuracy of radar are beam width, pulse
length, mechanical adjustment, and interpretation. Because of beam
width distortion, radar bearings are usually less accurate than radar
ranges. A fix obtained where two or more lines of position are
determined by ranges is more accurate than one obtained by bearings
alone. In most cases, radar ranges will always be available and will be
used over radar bearings.
Shorelines appear as they do on the chart; however, the PPI displays a
scaled down version of an area of the chart. Determining exactly what
you are seeing and where that area is on the chart takes practice.
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