Functions - JRC JMA-993-SA Instruction Manual

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FUNCTION
This equipment is high-performance radar equipment consisting of a scanner unit, a
transmitter-recover unit and a 23.1-inch color raster-scan LCD display unit
This radar complies with the current performance standards of the lMO.
I
Functions of This System
The JMA-9900 ARPA series is a color radar system designed to comply with the
international standards of the lMO. The main functions include; sea clutter and
rein/snow clutter suppression, sensitivity adjustment, interference reflector, bearing and
range measurement using a trackball, fixed/variable range makers, and electronic
bearing line, and ARPA functions (automatic/manual tiarget acquisition and tracking,
vector and trail displays, alarm displays and trial maneuvering).
In addition, the equipment has the functions of color display setting (4 views), own track
display, NAV line and marker displays, TM (True Motion) presentation, Self-diagnostic
facilities. and radar.
In addition, a radar switching function (lnterSwitch) can be added to switch between two,
four or eight radar units. However, in order to this function for four or eight units, an
external switching box is necessary.
f ARPA Functions
The ARPA functions that the JMA-9900 series incorporates will be outlined below.
I I ] First Stage : Target Detection from Radar Information
This work corresponds to plotting targets by band on the radar display. Assume that a
ship is approaching the own ship. You can catch the ship on the radar. Signals from the
ship are processed with the data processor and are transferred to the computer as
signals of bearing and arrange related to the own ship. ln this stage, the system has the
functions to quantization of radar information, to reject noises, to eliminate any
information other than ship information and to transfer necessary position data of ships
to the computer.
I II ] Second Stage : Target Tracking
Targets are plotted at intervals of 3 to 6 minutes with the radar, but tracking on this
system is to plot them electrically at intervals of fixed times. This means to compare
target position data to be detected every moment with those detected previously
changes of position data of the target.
[IIIJ Third Stage : Judgment of Existence of Ship in Danger of Collision
In this stage, the system calculates speed and @urses of a target ship from
ever-changing position data of the target ship obtained in the previous stage so as to
judge existence of any danger of collision. After the calculation, the system can easily
calculate the Closest Point of Approach (CPA) to the own ship and the time required to
reach the CPA (TCPA = Time to CPA). Both the CPA and the TCPA are compared with
the preset values previously set previously set according to the situations of the own
ship so as to judge existence of any danger of collision.
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