Raymarine Combined Pathfinder Radar Tuning the Receiver, Rain Clutter Control, using Rain and FTC

Chapter 3: Standard Radar Operations 3-9

and the echoes are not repetitive or consistent in position. With high winds and extreme conditions, echoes from sea clutter may cause dense background clutter in the shape of an almost solid disc.

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Figure 3-7: Sea Clutter

Adjusting Gain, Sea Clutter, Rain Clutter and Tune

The SEA control reduces the gain level in the areas near your vessel, extending up to 3 to 5nm depending on the wave and sea conditions. This has the effect of reducing the sea returns to intermittent small dots, while small targets are still visible. Gain levels further from your vessel remain unchanged.

You can use the gain and Sea control to help minimize the effects of side lobes (see Identifying False Echo Returns on page 3-5).

Note: On short range scales, do not set the Sea control so high that all clutter is removed, since this could stop you seeing echoes from close targets.

A

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TUNE

Tuning the Receiver

The TUNE control is used to fine tune the receiver in the scanner for maximum target returns on the display. In Auto mode, the radar tunes itself automatically on all range scales. We recommend that you leave the TUNE control in Auto

mode.

If you do set the TUNE control to Manual, you will need to adjust it about 10 minutes after you have turned on the radar, since the required setting changes once the magnetron has warmed up.

You should adjust the control to obtain the maximum signal strength, as indicated in the 8-step bar above the slider. If you cannot tune the radar successfully, refer to Section 7.6 for information on the Tune Preset function.

Rain Clutter Control, using RAIN and FTC

The radar can see echoes from rain or snow. Returns from storm areas and rain squalls consist of countless small echoes that continuously change size, intensity, and position. These returns, shown in Figure 3-8sometimes appear