Functions; Functions Of This Equipment; Functions Of Radar; Functions Of Ata (Option) - JRC JMA-7710-6 Instruction Manual

1.1

Functions

This equipment is a high performance, high quality, highly reliable and totally-large-scale-integrated
(excluding special electronic tubes) radar composed of a scanner, a transceiver and a display unit with a high
resolution color CRT which adopts the raster scan method.

1.1.1 Functions of This Equipment

1.1.1.1 Functions of Radar

The JMA-7700 series color radar is designed in accordance with IMO (International Maritime Organization)
specifications based on international standards. The major functions include target detecting color display,
sea, rain or snow clutter restraint, sensitivity adjustment, interference rejection, distance and bearing
measurement using a trackball, fixed and variable distance markers and an electronic cursor as well as
Standard equipment ATA (manual and automatic target acquisition and vector, tracking and warning display),
a plotter (own ship tracking and coastal line display) and an optional simple plotter (make and line display as
well as target and course setting).

1.1.1.2 Functions of ATA (Option)

This system, on which a radar is used as a sensor, can be outlined as follows by function:
[I] First Stage : Target Detection from Radar Information
This work corresponds to plotting targets by hand on the radar screen. 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 range related to
the own ship. In this stage, the system has the functions to quantize radar information, to reject
noises, to eliminate any information other than ship information and to transfer necessary position
data of ships to the computer.
[II] Second Stage : Target Tracking
Targets are plotted at intervals of 3 or 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 so as to check if they are of the same target and also to
save data of the target in its file so as to calculate changes of position data of the target.
[III] Third Stage : Judgement of Existence of Ship in Danger of Collision
In this stage, the system calculates speeds and courses 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 closes point of approach to the own ship
(CPA = Closest Point of Approach) and the time required to reach the CPA (TCPA = Time to CPA).
Both the CPA and the TCPA are compared with the value previously set according to the situations
of the own ship so as to judge existence of any danger of collision.
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