GENERAL RADAR DISPLAY TYPES

RAW VIDEO

Raw video displays are simply oscilloscopes that display the detected and amplified target return signal (and the receiver noise). Raw video displays require a human operator to interpret the various target noise and clutter signals.

In Figure 1, an operator could readily identify three targets and a ghost (a ghost is a phony target that usually fades in and out and could be caused by birds, weather, or odd temporary reflections - also referred to as an angel). Target 3 is a weak return and hidden in the noise - an operator can identify it as a target by the "mouse under the rug" effect of raising the noise base line.

SYNTHETIC VIDEO

Synthetic video displays use a computer to clean up the display by eliminating noise and clutter and creating it's own precise symbol for each target.

In the adjoining figure 2, target 1 comes and goes because it is barely above the receiver noise level - notice that it is quite clear on the raw video. Target 3 wasn't recognized by the computer because it's to far down in the noise. The computer validated the ghost as a target. The ghost might be a real target with glint or ECM characteristics that were recognized by the computer but not the operator.

SEARCH AND ACQUISITION RADARS

They generally use either a PPI or a sector PPI display. PPI displays can be either raw video or synthetic video.

PPI scope (plan position indicator).

• Polar plot of direction and distance.
• Displays all targets for 360 degrees.
  

Sector PPI scope

• Polar plot of direction and distance.
• Displays all targets within a specific sector.
• Origin may be offset so that "your" radar position may be off the scope.
  

TRACKING RADARS

Usually use some combination of A, B, C, or E scope displays. There are many other types of displays that have been used at one time or another - including meters - but those listed here are the most common in use today.

A-SCOPE

• Target signal amplitude vs range or velocity.
• Displays all targets along pencil beam for selected range limits.
• Displays tracking gate. Usually raw video. Some modern radars have raw video a-scopes as an adjunct to synthetic video displays.
• Must be used with a separate azimuth and elevation display of some sort.
• Also called a range scope (R-Scope).
  

B-SCOPE

• Range vs azimuth or elevation. Displays targets within selected limits.
• Displays tracking gate. May be raw or synthetic video.
• Surface radars usually have two. One azimuth/one elevation which can result in confusion with multiple targets.
  

• Azimuth vs elevation. Displays targets within selected limits of az and el.
• Displays tracking gate. May display bull's-eye or aim dot.
• May have range indicator inserted typically as a marker along one side. Usually synthetic video.
• Pilots eye view and very common in modern fighter aircraft heads up displays for target being tracked.
• Could be used in any application where radar operator needs an "aiming" or "cross hair" view like a rifle scope.
  

• Elevation vs Range similar to a B-scope, with elevation replacing azimuth.