1. OPERATIONAL OVERVIEW
1-17
1.16
Measuring the Range to a Target
The range to a target may be measured three ways: with the fixed range rings, with the cursor (if
set to measure range and bearing), or with the VRM.
Use the fixed range rings to obtain a rough estimate of the range to a target. They are the concen-
tric solid circles about own ship, or the sweep origin. The number of rings is automatically deter-
mined by the selected range scale and their interval is displayed at the upper-left position of the
screen. Count the number of rings between the center of the display and the target. Check the
range ring interval and judge the distance of the echo from the inner edge of the nearest ring.
1.16.1
Adjusting range ring brilliance
1. Press the
MENU
key to open the menu.
2. Choose the Brill/Color menu and then press the
ENTER
key.
3. Choose Range Rings Brill and then press the
ENTER
key.
4. Choose appropriate brilliance and then press the
ENTER
key.
5. Press the
MENU
key to close the menu.
1.16.2
Measuring range by the variable range marker (VRM)
There are two VRMs, No. 1 and No. 2, which appear as dashed rings so that you can discriminate
them from the fixed range rings. The two VRMs can be distinguished from each other by different
lengths of dashes.
1. Press the
VRM
key to display either
of the VRMs. Successively pressing
the
VRM
key toggles the active
VRM between No. 1 and No. 2. The
currently active marker is enclosed
with >.....<.
2. Operate the Trackball to align the
active variable range marker with
the inner edge of the target of
interest and read its distance at the
lower-right corner of the screen.
Each VRM remains at the same
geographical distance when you
operate the
RANGE
key. This
means that the apparent radius of
the VRM ring changes in proportion
to the selected range scale.
3. Press the
VRM
key to erase each
VRM.
Off
Low
Medium
High
VRM1
+ 96.8
°
R 0.338 NM
VRM2 0.140
NM
VRM1, VRM2
range
VRM1>0.007
NM
<
+
VRM2
Target
How to measure range with VRMs
