Error Between Radar Echo Image And Chart - Furuno FMD-3200 Operator's Manual

16. RADAR OVERLAY
16.4

Error Between Radar Echo Image and Chart

There are several reasons why the radar echo image and chart display do not match
exactly. The mismatch is a combination of several reasons and removing one reason
doesn't solve the mismatch perfectly. There is a fundamental difference between the
radar echo image and corresponding chart feature. The radar echo is a reflection from
the real life target and the actual position of the real life target is the front edge of the
radar echo. Therefore, the radar echo should start from the chart feature and exist as
far as the radar pulse length goes.
How to compensate for bearing error
Bearing error occurs in the following instances:
• Gyro error
• Inaccurate chart
• Improper installation parameters (radar overlay bearing offset)
How to compensate for position error
Position is caused by the following:
• Inaccurate position
• Position offset
• Inaccurate chart
• Improper installation parameters (conning position offset, position receiver antenna
offset, radar overlay range offset)
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