Furuno FR-8051 - Manual (Page 34)

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True trails Relative trails
Figure 1-21 True and relative echo trails.
Note: If the true trail is selected on the stabilized
RM (CU, NU), targets whose extensions hit own
ship are not always on a collision course.
Starting echo trail
Press the ECHO TRAIL key to start the echo trail
function. "REL (or TRU) TRAIL", the echo trail
time selected (on the TRAIL menu) and elapsed
time appear at the top right-hand corner of the
display. Then, afterglow starts extending from all
targets.
Canceling echo trail
Press the ECHO TRAIL key to erase echo trails
and echo trail indications.
Trail time
Trail time can be selected on the TRAIL menu.
1) Press the MENU key.
2) Select the TRAIL menu.
3) Press the ENTER/SELECT key.
4) Select TIME and press the ENTER/SELECT
key.
5) Select trail time among 15 seconds, 30 sec-
onds, 1, 3, 6, 15, 30 min, or continuous (99
minutes 59 seconds).
6) Press the ENTER/SELECT key.
7) Press the MENU key.
Trail reference
Echo trails can be displayed relative to own ship
(relative) or with reference to north (true).
1) Press the MENU key.
2) Select the TRAIL menu.
3) Press the ENTER/SELECT key.
4) Select MODE and press the ENTER/SELECT
key.
5) Select trail reference; true or relative.
6) Press the ENTER/SELECT key.
7) Press the MENU key.
Trail gradation
Echo trails may be shown in monotone or gradual
shading (multiple). Gradual shading paints the
trails getting thinner with time just like the after-
glow on an analog PPI radar.
Monotone trail Multitone trail
Figure 1-22 Comparison of
trail gradation types
1) Press the MENU key.
2) Select the TRAIL menu.
3) Press the ENTER/SELECT key.
4) Select TONE and press the ENTER/SELECT
key.
5) Select SGL or MULT.
6) Press the ENTER/SELECT key.
7) Press the MENU key.