mitter. It can also provide a zero range start signal for
the display device.
Basic pulse-radar systems are rather complex in
their composition, but they all contain the same basic
functional areas, with additional equipment included
for specific purposes. For instance, a search radar
requires additional circuitry to indicate antenna azi-
muth position coincident with a particular target echo.
radar for moving-target indication (MTI) and to filter
out stationary targets, landmasses, and clutter from
weather and the sea state.
A tracking radar, such as a fire-control radar, re-
quires additional circuitry to measure target range, az-
imuth, and elevation. Since circuitry is also required
to keep the antenna pointed at the target, fire-control
radars have ranging and angle tracking systems in-
Additional circuitry might also be added to a search
—
cluded. Figure 2-1 shows a basic pulse radar.
Figure 2-1.—Basic pulse radar.
Pulse-Doppler Radar System
Pulse-Doppler radar, however, has some disadvan-
A pulse-Doppler radar has certain advantages over
a basic pulse radar or a continuous-wave radar. It can
detect both stationary and moving targets and can also
determine range. In addition, it can distinguish be-
tween two targets with the same radial velocity, but at
different ranges. The radial velocity is the apparent
speed that the target is closing on or going away from
the radar.
2-2
tages, too: blind target ranges and velocities, range
and delivery ambiguities, and reduction in maximum
range capabilities. These disadvantages can be com-
pensated for by using additional circuitry.
A pulse radar’s echo signal also contains velocity
information in the Doppler frequency information, but
the signal is not normally used by a basic pulse radar.
By using the Doppler signal available on an echo sig-
