Borje Wallin - The Adlard Coles Book of Radar

This radar starts when the knob is set to Standby.

Every radar set consists of an antenna, a display and the electronics that deal with the signals.

On older radar screens the image was drawn by the sweep, which is seen as a line rotating at the same speed as the antenna. This technology, in which the picture is preserved for a short while by the afterglow in the fluorescent layer of a Cathode Ray Tube (CRT), results in an incomplete image on the screen.

A modern set for small craft has a flat screen that uses a Liquid Crystal Display (LCD). In this type of set the contacts are stored in a picture memory, and renewed for every antenna revolution. The entire image is seen all the time, which can make the picture easier to interpret. LCD images are also easily visible in daylight.

However, with regard to adjustment of the set and interpretation of the image, there is very little practical difference between different types of display.

No pulse-emitting radar shows a picture immediately after switching on because the set has to warm up, but when the set is ready to transmit, the message Standby will appear on the screen. After that time, pushing a button labelled Transmit or TX will activate transmission of microwaves and the radar may or may not start to show a picture, depending on how the other controls are set. When in Standby, the radar is warm and ready to use but is not actually transmitting, so returning the radar to Standby will save energy if you take a break away from the set, but the radar will still be instantly useable.

When the radar set is switched to Transmit, what you first see on the radar screen varies, depending on the settings in use when the radar was last switched off and the differences in sea and weather conditions between then and now. Because of this the image will almost certainly need adjustment and you may not even have an image at all. When you need to adjust the image from scratch, proceed as below.

Rain and sea clutter

Start by turning the Rain Clutter and Sea Clutter controls to zero. These can be adjusted later to diminish annoying contacts from rain and waves, and adjusting them at the beginning can reduce useful contacts during the initial set-up.

Rain and Sea Clutter controls on a modern radar, controlled by soft buttons.

Rain Clutter is controlled by a knob on older sets.

Brilliance

Next you need to adjust Brilliance, increase it until the text and graphics are clear but not dazzling. This control adjusts the general brightness of the screen. On some radar sets it may have another name, for example Brightness or Light.

Change Brilliance as the ambient light around the radar changes. Generally, its recommended to adjust the radar screen until its just bright enough to be seen clearly, but not so bright that you struggle to distinguish the details.

Many sets have the facility to change the colours so they wont disturb your night vision.

Some monochrome radar displays also have a control known as Contrast which adjusts the characteristics of the display to suit the intensity and angle of the approaching light, and the direction from which it is being viewed. Adjusting it is simply a matter of trial and error to get the best picture for the prevailing conditions.

Tune

Now proceed with Tune. This function tunes the receiver to the frequency that is being transmitted. Many modern radar sets have an automatic Tune, but you may encounter sets with both automatic and manual Tune.

If Tune needs to be set manually, home in on the best adjustment by turning the control to and fro. There is usually an indicator to show the optimal setting (in the picture below, this is above the Tune bar).