Selecting Pulselength; Receiver Sensitivity; Suppressing Sea Returns - Furuno FR-7041R-MARK-2 Operator's Manual

1.9

Selecting Pulselength

The pulselength in use is displayed at the upper left corner of the display.
Appropriate pulselengths are preset to individual range scales and function keys.
Therefore, you are not usually required to select them. If you are not satisfied with
the current pulselength setting, however, it is possible to change it for the 3 and 6
kilometer ranges as below. Generally, select a long pulse for longer detection
range and short pulse for better range discrimination.
1. Press the [MENU] key to show the main menu.
2. Use the trackball to select OTHER MENU and press the [ENTER] key.
3. Use the trackball to select the item "6. Pulselength."
4. Use the trackball to select pulselength desired (SHORT or LONG) and press
the [ENTER] key.
5. Press the [MENU] key to close the menu.
Range
Long
Short
1.10

Receiver Sensitivity

The [GAIN] control adjusts the sensitivity of the receiver. It works in precisely the
same manner as the volume control of a broadcast receiver, amplifying the
signals received.
The proper setting is such that the background noise is just visible on the screen.
Adjust the sensitivity on the highest range; the background noise is clearer on
that range. If you set up for too little sensitivity, weak echoes may be missed. On
the other hand excessive sensitivity yields too much background noise; strong
targets may be missed because of the poor contrast between desired echoes and
the background noise on the display.
1. Transmit on long range.
2. Adjust the [GAIN] control so background noise is just visible on the screen.
1.11

Suppressing Sea Returns

Echoes from waves can be troublesome, covering the central part of the display
with random signals known as sea clutter. The higher the waves, and the higher
the antenna above the water, the further the clutter will extend. Sea clutter
appears on the display as many small echoes which might affect radar
performance. (See the left-hand figure in Figure 1-7.) When sea clutter masks the
picture, adjust the [A/C SEA] control to reduce the clutter.
3 nm 6 nm
MP LP
SP MP
1. OPERATION
1-7