Adjust Your Radar for the Best Picture

No other electronic instrument offers the versatility or multitasking of the modern radar. It gives navigational information, tracks targets, allows entry into port during fog, and warns of approaching squalls and storms.

Newer radars even interface with GPS receivers and chart plotters.
Most modern radars have automatic tuning, but knowing how to adjust yours manually puts you in control and oft en gives a sharper picture.

THE FIVE MAIN CONTROLS TO GET YOU STARTED

Brilliance:

Contrast:

As on a computer screen, the contrast control changes the vibrancy of an image or text. Increase contrast to sharpen images and text. Decrease contrast for a softer effect.

Gain:

This is the system’s main receiver control. Gain measures the ability of the receiver to process the reflected signal properly. Use the gain control to  tweak the radar for a good picture.

Sea clutter (STC):

Use this control to clear up screen clutter caused by signal
reflections from wave or swell faces.

Rain clutter (FTC): 

Use this control to clear up screen clutter caused by signal
reflections from rain, squalls, or storms.

START WITH A WARM-UP

If you’ll use the radar with the engine running, start your engine or engines.

Turn on all electronic gear. Then turn on the radar receiver. Wait 2 to 3minutes before beginning adjustments.

ADJUSTING FOR RAIN, SQUALL, WAVES, AND SWELL

Water droplets, when massed together, provide an excellent reflective surface.

Rain and squalls appear as clusters of dots anywhere on the scope. Sea waves appear as a mass of clutter at the center of the scope. Make rain clutter (FTC) or sea clutter (STC) adjustments in small increments.

The rain clutter control clears interference over the entire scope at once; the sea clutter control clears clutter from the scope center outward.

Use a turn-stop-watch method of incremental adjustment with any control.

Crank a tad and stop cranking.

Watch the scope for several sweeps.

Wait for a target to paint more than once in the same spot. If you see nothing, repeat the turn-stop method.

Easy does it.

You want to adjust for the best picture without washing out small, hidden targets.

PROPER GAIN ADJUSTMENT

Gain determines the ability of your radar receiver to amplify a signal refl ected from a vessel, landmass, or buoy. Concentrate on properly adjusting the gain control.

Good gain adjustment rewards you with three vital features for safety:

1. Detection of long- and short-range targets.

2. Separation of targets close to one another. For example, two vessels
close together appear as individual targets instead of as one large target.

3. Acquisition of weak refl ection targets (wooden vessels, targets with round versus flat surfaces).

How to Adjust Your Gain for the Best Picture

Try to adjust gain in relatively calm weather with no rain or wave activity.

1. Turn off the rain and sea clutter controls.

2. Turn the gain control down all the way.

3. Set the range scale to the maximum for your vessel, based on your antenna height (see Appendix I for a table). Find a distant object just  inside this range.

4. Turn up the gain very slowly until you just begin acquiring your
selected target. You should see a light speckle of dots on the scope.

5. Reset brightness and contrast collectively for the best picture. Take care not to wash out small targets with too much brilliance or lose them with too little brilliance.

6. Mark the gain setting on the radar with tape or a felt-tip pen. Th at way you can quickly return to the proper setting aft er changing gain or range scales. Lower the gain a bit when trying to pick up closer targets; raise it for distant targets.

TARGET STRENGTH AND THE ART OF BECOMING “RADAR-VISIBLE

A radar signal requires a large amount of mass for good refl ectivity. It doesn’t matter whether the mass consists of wood, paper, plastic, or metal. A large, flat
surface that is perpendicular to the radar signal paints a sharp radar image. (Note, However that sails do not refl ect radar signals well.) Smaller, rounded shapes
(sailboat hulls and masts) present a poor refl ective surface to the signal.

Large ships often miss smaller targets at relatively close range.

Their high antennas send out a narrow, cone-shaped signal, skipping over these close targets. In heavy weather, huge seas or swells hide small targets, making
detection diffi cult or impossible.

Hoist one or more radar reflectors to make your boat visible to other
radar-equipped vessels. Reflectors come in all sizes and shapes, from simple plates to a vitamin-pill-shaped canister. In recent radar refl ector testing, the
trihedral-shaped reflector took home the gold. This design consists of three round plates that intersect one another at 90-degree angles.

For the strongest signal return, hoist the reflector in a “rain catcher” position. To do this, make sure two of the plates form a “V” shape when pointing skyward.