Seiwa SWRx series - Manual (Page 45)

47 User Manual
6.20 What are the functions that require a GPS or a Heading
Sensor?
Function Heading GPS FIX
North Up Radar orientation Y N
Track Up Radar orientation Y N
True Motion mode Y Y
Chart Overlay Y Y
Radar/Chart Synchronization Y Y
Cursor Echo Y Y
Head Up Mode N N
Relative Motion mode N N
6.21 Is it better a gyrocompass or a flux gate compass?
The gyrocompass it is a better choice because it is faster but it is much more
expensive. The flux gate compass is slower but it is much cheaper. Using a flux-
gate you have to expect to see delays in the rotation of the chart when in Chart
Overlay mode.
6.22 How can I be advised of potential dangers for the
navigation?
Using the Guard Zone alarms.
6.23 What are Guard Zones?
Guard Zones are zones defined by the user that causes an audible and visual
alarm to be triggered when a target exceeding a certain density enters into it. The
density of the target that may trigger the alarm is regulated by mean of the
Guard Zone sensitivity. There are of two types of Guard Zones: Circular or Secto-
rial. They are fixed with respect to the ship position and heading but their range
and orientation (only for sector type) are user defined.
6.24 How should I set the Guard Zone sensitivity?
Guard Zone sensitivity must be regulated accordingly to the current Gain of the
Radar. The higher the sensitivity the smaller the target that may trigger the alarm.
In general if you regulated your Radar to obtain a clean picture you can set the
Guard Zone sensitivity very high to detect even the smaller targets. In case the
Radar picture has clutter present due to the higher gain set, you'll have to reduce
the Guard Zone sensitivity to avoid triggering false alarms. In general a way to
set the maximum sensitivity for a Guard Zone is to start increasing the sensitivity
until an alarm is triggered and then reduce the sensitivity until the alarm stops.