User's Manual

Synapsis Radar
with Nautoscan NX Pedestal
Operator Manual
4265.DOC020102
3-16
Edition July 2015
3.4.1 Sensor Errors
The performance of ARPA depends on the quality of the sensor information
which is processed. The Radar is the sensor which measures target range and
bearing relative to own ship. The gyro compass measures the heading of the
own ship relative to north. The speed log measures the motion of own ship
relative to the water or bottom.
3.4.1.1 Gyro Compass
A precise Gyro Compass heading is an important condition for accurate target
tracking and ARPA information. The Radar user should be aware that Gyro
Compasses may have errors (speed error and acceleration error). These errors
can degrade the accuracy of target results (ARPA INFO).
Raytheon Gyro Compasses have automatic error correction and supply true
heading to Radars.
This may not be the case for other Gyro Compass models.
If Gyro Compass heading input is interrupted, the Radar will give alarm.
3.4.1.2 Speed Log
A precise speed input from the log is an important condition for accurate target
tracking and ARPA INFO. The Radar user should be aware that speed outputs
of logs may be temporarily unstable for various reasons. This may degrade the
accuracy tracking results (ARPA INFO).
If speed input is interrupted, the Radar will give alarm.
3.4.1.3 Plotting
Plotting is started by positioning the trackball cursor over the desired target
echo. When the soft button is pressed the Radar acquires the target.
When a target becomes too weak or too large and is identified by the ARPA as
a LOST TARGET, two options are available:
(1) CANCEL Option: As a warning, a flashing symbol marks the last
position of the target. The ARPA attempts the target by increasing the
window size.
It coasts for five scans (antenna rotations) and if the target is not located
in the enlarged window, the plot is cancelled.