Furuno FAR-1416, Руководство оператора

Страница: 91 / 226

3-1
3. TARGET TRACKING (TT)
3.1 Precautions for Target Tracking Usage
WARNIN WARNING
No one navigational aid should be relied
upon for the safety of vessel and crew.
The navigator has the responsibility to
check all aids available to confirm
position. Electronic aids are not a
substitute for basic navigational
principles and common sense.
This TT automatically tracks automatically or
manually acquired radar targets and
calculates their courses and speeds,
indicating them by vectors. Since the data
generated by the auto plotter are based on
what radar targets are selected, the radar
must always be optimally tuned for use with
the auto plotter, to ensure required targets
will not be lost or unwanted targets such as
sea returns and noise will not be acquired
and tracked.
A target does not always mean a land-mass,
reef, ships or other surface vessels but can
imply returns from sea surface and clutter.
As the level of clutter changes with
environment, the operator should properly
adjust the [A/C SEA], [A/C RAIN] and [GAIN]
controls to be sure target echoes are not
eliminated from the radar screen.
CAUTION
The plotting accuracy and response of
this TT meets IMO standards. Tracking
accuracy is affected by the following:
Tracking accuracy is affected by course
change. One to two minutes is required to
restore vectors to full accuracy after an
abrupt course change. (The actual amount
depends on gyrocompass specifications.)
The amount of tracking delay is inversely
proportional to the relative speed of the
target. Delay is on the order of 15 - 30
seconds for high relative speed; 30 - 60
seconds for low relative speed.
The target tracking and pertinent vector
calculation accuracy is influenced by the
following:
- Echo intensity
- The range measurement accuracy;
characterized by both random and biased
measurement errors.
- The angular measurement accuracy;
characterized by beam shape, target glint
and bias errors.
- Radar transmission pulsewidth
- Gyrocompass heading error
- Speed log error
- Curent and wind (set & drift)
- Course change (own ship and target)