Smiths Kelvin Hughes Nucleus 3 5000 Series, System Handbook

Page: 68 / 510

ELEC TRONIC PLOTTING AID
IN TRO DUC TION
1 Manta displays are provided with one of three radar
plotting aids:
(1) EPA - A Manual E lectronic P lotting A id.
(2) ATA - An A utomatic T racking A id with manual
acquisition and a limited subset of ARPA
functions.
(3)
ARPA - A comprehensive A utomatic R adar
P lotting A id with manual and automatic acquisition
and including all ARPA functions.
2 This section covers the Electronic Plotting Aid (EPA).
3
The specification for the Electronic Plotting Aid (EPA)
is provided at the end of this Chapter.
4 The EPA is a manual plotting system equivalent to, but
superior than, a reflection plotter. Up to 20 targets may
be plotted.
5 The operator enters an initial plot at a target position,
followed by a second plot some minutes later (typically
3 to 6 minutes). The two plots are used to calculate the target
true course (CRSE), speed, CPA and TCPA, and to
generate a vector. The calculation and vector are ONLY
based on the previous two plots.
6
The vector origin is RATE AIDED and therefore moves
at the predicted course (CRSE) and speed of the
target. Should the vector deviate from the target, it may be
that the target has manoeuvred. If Ownship changes course
or speed, relative vectors instantly indicate the changes in
CPA and TCPA status. Whenever any target manoeuvres
(vector leaves target) a plot update is required.
ELEC TRONIC PLOTTING AID CON TROLS
NOTE: - APPLIES TO EU MODE ONLY
An operator warning is displayed if the target is not
updated for 10.5 minutes. The target is automatically
deleted and the warning cancelled if a new plot is not
acquired within 11.5 minutes.
7 To plot a single target and obtain target data proceed
as follows:
(1) Position the cursor over the target, press the ACQ
(Acquire) pushbutton (left-hand) a plot symbol [•]
appears over the target position. Release the
ACQ pushbutton.
(2) Target data, other than Range and Bearing
(BRG), is not available until the initial plot has
been updated. The equipment accepts an update
immediately after the entry of the next plot and
target data is shown.
(3) To update the plot, position the cursor over the [•]
symbol of the target, press the SELECT
pushbutton (centre), the [•] symbol flashes to
acknowledge selection. Now reposition the cursor
over the present position of the target and press
the ACQ (Acquire) pushbutton, a vector is
generated representative of the target course
(CRSE) and speed.
(4) Release the ACQ (Acquire) pushbutton. The
vector origin will move at a course and speed
predicted from the two previous plots. It is
recommended that the LEADING EDGE of the
target is used for a plot entry or update, to ensure
consistent plotting.
NOTE:
Vectors are normally relative if in the Relative Motion
RM(R) mode and true if in the True Motion TM(T) mode.
(5) Further plots on the target are made by repeating
sub-paragraph (3) . The previous plot symbols
and vector flash to acknowledge selection.
Reposition the cursor over the present target
position and press ACQ (Acquire), the previous
vector disappears and a new vector is generated.
(6) If the vector deviates from the target track,
reposition the cursor to select the target and press
the ACQ (Acquire) pushbutton, the vector is
recalculated using the new data.
(7) To display target data, position the cursor on or
near to the vector origin and press the SELECT
pushbutton. The plot symbols and vector flash,
target data is displayed in the Target Data box on
the right-hand side of the screen. The range and
bearing of a target plot is displayed if selected and
only the initial plot has been entered.
NOTE:
Following the selection of SELECT, the target vector and
plot symbols will flash. Careful selection of the pushbutton
functions is advised as the options are: CANCEL ENTRY,
ACQ or DELETE PLOT.
(8) The vector presentation mode can be reversed by
pressing and holding the VECTOR MODE
pushbutton, to display true vectors when the
equipment is in the Relative Motion RM(R) mode
and relative vectors when the equipment is in the
True Motion TM(T) or Relative Motion RM(T)
mode.
NOTE:
Releasing the VECTOR MODE pushbutton within 4
seconds allows the vectors to return to the normal mode.
8
Changes in range scale, Off-centering, Relative or
True Motion or stabilisation mode (NORTH UP,
COURSE UP, HEAD UP) does not result in any loss of plots.
Vectors correspond to the motion selected.
KH 2020
Chap 2a
Amdt 5 2a.1 July 03
CHAPTER 2A
RADAR PLOTTING AIDS