Furuno 841 User Manual download pdf (Page 54)

43

6) As a final test, move the boat towards a

small buoy and confirm that the buoy

shows up dead ahead on the radar when

it is visually dead ahead.

5.8 Sweep Timing

This adjustment ensures proper radar per-

formance, especially on short ranges. The

radar measures the time required for a trans-

mitted echo to travel to the target and return

to the source. The received echo appears on

the display based on this time. Thus, at the

instant the transmitter is fired, the sweep

should start from the center of the display

(sometimes called sweep origin.)

A trigger pulse generated in the display unit

goes to the antenna unit through the signal

cable to trigger the transmitter (magnetron).

The time taken by the signal to travel up to

the antenna unit varies, depending largely

on the length of signal cable. During this

period the display unit should wait before

starting the sweep. When the display unit is

not adjusted correctly, the echoes from a

straight local object (for example, a harbor

wall or straight pier) will not appear with

straight edges—namely, they will be seen

as “pushed out” or “pulled in” near the pic-

ture center. The range of objects will also

be incorrectly shown.

metILEDOM

128

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148

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5#408PTV1.2-7.15#308PTV1.1-9.0gnol,xT

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6#408PTV1.8-9.74#308PTV6.7-4.7yb-dnatS

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Table 5-1 Voltage ratings (reference for installer)

(1) Correct

(2) Target pushed

inward

(3) Target pushed

outward

Figure 5-21 Examples of improper and

correct sweep timings

1) Transmit the radar on the shortest range

and adjust the sensitivity and STC.

2) Visually select a straight echo (harbor

wall, straight pier).

3) Display the Installation Setup 2 menu

and select Adjust Sweep Timing.

5) While looking at the target selected at

step 2, press cursor pad at the 9 o’clock

or 3 o’clock position to straighten the tar-

get.

6) Press the [ENT] key.

5.9 Closing the Installation

Menus

Press the [MENU] key and turn off the

power.

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