Radar System Engineering

164 THE GATHERING AND PRESENTATION OF RADAR DATA (SEC.6.4
I. One-dimensional deflection-modulated displays. These invariably
present range. Two such displays on a single tube are
sometimes used to obtain directional information by comparing
signal intensities from two different beam lobes.
II. Two-dimensional intensity-modulated displays.
A. The representation of a horizontal or vertical plane.
1. Undeformed displays. Because of the nature of the
radar data these are usually in the form of polar plots of
range and angle (PPI).
2. Deformed displays.
a. Radial deformation of a polar plot created by a shift
in the range origin.
b. Linear deformation produced by “stretching” a polar
plot along one rectangular axis.
c. Rectangular plots of range and angle.
B. Rectangular plots of azimuth and elevation.
1. True displays which follow the antenna orientation.
2. Error indicators. (Such displays are not always intensitymodulated.
)
111. Three-dimensional intensity-modulated displays. These are
all modifications of .wo-dirnensional displays which make use
of one or both of the coordinates on the tube face to present,
in a formalized way, information about the third dimension
being displayed.
6.4. One-dimensional Deflection-modulated Display s.—Since onedimensional
displays yield little geometrical information, their only
justification is that they permit the use of deflection modulation, which
gives a maximum of information about the intensity and form of the
echo signals. For this purpose, it is best to display the signals as a
function of time or range, and thus the only displays using deflection
modulation are those in which the deflections are applied perpendicular
to a range sweep (Fig. 6“1). This sweep may represent either a small
part or nearly all of the period between successive pulses. In the
former case, the particular range interval that appears on the display
is determined by the delay elapsing between the transmission of the
outgoing pulse and the starting of the range sweep.
The general classification “type A” is used to describe one-dimensional
displays. An A-scope is universally used for observing radar
signals and various circuit waveforms in a radar set during test and
alignment. It may be either part of the permanent installation or a
piece of portable test equipment. The laboratory analogue of the
A-scope has come to be known as a‘’ synchroscope”; it is an indispensable
tool in the design and testing of electronic circuits.