generally used to determine the height or elevation
angle only. Range is determined from processing or a
type P display.
TYPE P.—This display is commonly called a PPI
(plan position indicator).
Own ship is usually the
center. Range is measured radially from the center.
The range display can be selected, and the radar source
is usually selectable. The PPI can display raw video or
symbology and alphanumerics, or both. The type P
display is most commonly found in the Combat
Information Center (CIC) and in weapons control
stations.
Additional information on how individual displays
are produced is available in NEETS modules 6, 9, and
18.
Antenna System
The antenna system routes the pulse from the
transmitter, radiates it in a directional beam, picks up
the returning echo, and passes it to the receiver with a
minimum of loss. The antenna system includes the
antenna; transmission lines and waveguide from the
transmitter to the antenna; and transmission lines and
waveguide from the antenna to the receiver.
Before we discuss some types of antennas used in
fire control, we need to review the basic principles of
electromagnetic wave radiation and reflectors.
The radar energy that forms the target-tracking
and illumination beams is transmitted by an antenna
at the control point. Radiated energy tends to spread
1-7
Figure 1-5.—Types of radar displays.
